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AP Bio

CBSE Biology

CBSE Chemistry

CBSE Physics

CBSE Science

General Bio

General Chemistry

General Physics

Room 1

# **Chapter 13: Magnetic Effects of Electric Current**

**Field and Field Lines**

* A magnet is a substance that creates a magnetic field that attracts or repels other magnetic materials.
* Lodestone is a type of magnet that occurs naturally. It attracts metals such as iron, nickel, and cobalt, among others.

**North and South Poles**

* A bipolar magnet is always bipolar, possessing north and south poles. 
* These two poles are inextricably linked and cannot be separated. 
* When a magnet is freely hanging, its north pole is the side that faces Earth's geographic north.

**Like poles repel and unlike poles attract**

* Poles attract and repel in the same way as charges do. 
* Poles that are similar repel each other, whereas poles that are dissimilar attract each other.

**Bar magnet**

* A bar magnet is a rectangular item with permanent magnetic qualities made of iron, steel, or any other ferromagnetic material. 
* It has two poles, one north and one south, and when hanging freely, the north pole aligns itself with the Earth's geographic north pole.

**Magnetic field**

* A magnetic field is the region around a magnet where its magnetic effect may be felt. Magnetic lines of force represent the direction and strength of a magnetic field.
* A bar magnet is used to test iron filings.
* The magnetic field lines that round a bar magnet are seen in the iron filings that surround it. Magnetic field lines can be thought of as fictitious lines that visually illustrate the magnetic field that surrounds any magnetic material.

**Lines of magnetic field**

* Magnetic field lines produce continuous/running closed loops as a result of the magnet's magnetic field lines.
* The direction of the total magnetic field at any given position is shown by the tangent to the field line.
* The magnitude of the magnetic field is proportional to the number of field lines crossing per unit area. The bigger the number of field lines crossing per unit area, the higher the intensity.
* There is no point where the magnetic field lines cross.
* Lines of magnetic field for a closed loop
* Magnetic field lines must begin and terminate because magnets contain dipoles. As a result, it starts at the north pole and goes south outside the bar magnet, then from south to north inside the magnet, according to convention. As a result, it creates closed loops.
* There are no magnetic field lines that cross one other.
* Magnetic field lines do not cross because two tangential magnetic field directions would be linked with the same location, which is not the case. When a compass needle is positioned at that location, it shows two separate magnetic field directions, which is nonsensical.
* Magnetic field lines indicate the relative intensity of the magnetic field.
* The magnetic field's intensity increases as the magnetic field lines become closer or denser.

## **MAGNETIC FIELD DUE TO CURRENT CARRYING CONDUCTORS**

**Oersted’s experiment**

* A magnetic field is created when electric current travels through a current carrying conductor. 
* A magnetic needle that demonstrates deflection can be used to demonstrate this. The deflection increases as the current increases. 
* When the current is reversed, the direction of deflection is reversed as well.

**Electromagnetism and electromagnet**

* An electromagnet is a man-made magnet that generates a magnetic field when an electric current passes through a conductor. 
* When the current is switched off, this field vanishes. 
* Electromagnetism is the phenomena of creating or inducing a magnetic field as a result of the passage of an electric current.

**Magnetic field due to a straight current carrying conductor**

* A magnetic field is created around a straight current-carrying conductor when electricity is transmitted through it. 
* We can see that the iron filings organise themselves in concentric circles around the conductor when we use them.

**Right-hand thumb rule**

![right hand rule](//images.ctfassets.net/4yflszkpcwkto/2lvMRlhyU73ZTLYfugec9b/8b1bec7f7086fae4193227cdcf86d0ec/original_AP10_Electromagnetism_Figure1.png)
[Source: ](https://byjus.com/question-answer/according-to-the-right-hand-thumb-rule-if-the-thumb-points-in-the-direction-of/)

* When a straight conductor is held in the right hand with the thumb pointing in the direction of the current, the tips or curls of the fingers indicate the direction of the magnetic field surrounding it.
* Current across a circular loop produces a magnetic field.
* A circular conducting wire with tiny straight segments may be measured using the right-hand thumb rule. 
* Every point on the current-carrying wire generates a magnetic field in the centre, which appears as straight lines.

**Magnetic field due to current in a solenoid**

* A solenoid is a cylinder-shaped coil made up of several circular windings. 
* When current is run through it, it acts like a bar magnet, creating a field pattern that is extremely similar to that of a bar magnet. 
* A soft iron core is employed to boost the strength.

**Ampere’s experiment**

* An electric conductor is subjected to a force when it is put in a magnetic field. 
* This force is proportional to the current and perpendicular to the length and magnetic field of the current.

**Fleming’s left-hand rule**

* The direction of force applied to a current carrying wire must be perpendicular to both the current direction and the magnetic field, according to Fleming's left hand rule.

**Electric motor**

* Electrical energy is converted into mechanical energy by an electric motor.
* Brush X allows current to enter arm AB, while brush Y allows current to travel from C to D. We can see that the force pulls AB downwards and CD upwards using Fleming's LHR.
* The split rings PQ operate as a commutator in an electric motor, reversing the current direction. The current reversal is repeated every half rotation, resulting in a continuous rotation of the coil.

## **ELECTROMAGNETIC INDUCTION AND ELECTRIC GENERATOR**

**Faraday’s experiment**

* By electromagnetic induction, Faraday showed that a magnetic field interacts with an electric circuit by generating a voltage known as EMF (electromotive force).
* A current is established in the coil circuit when a magnet is moved towards it, as shown by a deflection in the galvanometer needle.

**Electromagnetic induction**

* The formation of induced EMF and hence current in a coil owing to a shifting magnetic field over time is known as electromagnetic induction. 
* The magnetic field changes when a coil is put near a current-carrying conductor owing to a change in I or relative motion between the coil and conductor. 
* Fleming's right-hand rule determines the direction of the induced current.

**Fleming’s right-hand rule**

* The thumb, forefinger, and middle finger of the right hand are extended perpendicular to each other according to Fleming's right-hand rule, as seen below. 
* If the thumb points in the direction of conductor movement, the forefinger points in the direction of the magnetic field, and the middle finger points in the direction of the induced current, then the middle finger points in the direction of the induced current.

**Electric generator**

* Mechanical energy is converted into electrical energy by this gadget.
* The principle of operation is electromagnetic induction.
* The axle connecting to the two rings is rotated, causing the arms AB and CD to move up and down in the created magnetic field, respectively. As a result, the induced current is directed through ABCD.
* The direction of current in both arms changes after half revolution. The induced currents are created in these arms along directions DC and BA, again using Fleming's right hand rule, so the induced I flows through DCBA.
* DC Generators: They function similarly to AC generators, but instead employ half rings to create current in a single direction with no magnitude fluctuations.

## **DOMESTIC ELECTRIC CIRCUITS**

**Fuse**

* In the event of an electrical circuit overloading, a fuse serves as a protection measure.
* When the neutral and live wires come into touch owing to insulation damage or a line failure, overloading occurs.
* When the circuit is overloaded, the current in the circuit rises (short circuit) and becomes dangerous. The fuse device melts the circuit and interrupts current flow due to Joule heating (resistive or ohmic heating on current passage).
* The voltage of the livewire is 220 V, and it is insulated with red insulation.
* The earth line is wrapped in green insulation and has a voltage of 0 V (the same as Earth).
* The neutral wire is insulated with black insulation.
* We have 220 V AC electric electricity at a frequency of 50 Hz in our homes.

**Transmission loss of power**

* Joule's heating causes power losses in transmission cables over long distances. Losses are caused by the heat (H) l2R, where R is the line resistance.

[Source: ](https://ncert.nic.in/textbook/pdf/jesc113.pdf)

The behaviour of an electric current-carrying wire is similar to that of a magnet. The magnetic effect of electric electricity is used in electromagnets and electric motors. A magnetic field is created when electric current travels through a current carrying conductor.

Our CBSE study guides are structured to mimic your chapter-wise, detailed, revision notes! We’ve ensured to structure our guides around crucial concepts that you’ll need to ace your exams, while being quick and easy to understand. Make sure to also check out the supporting VR-based classrooms and study sessions on Inspirit!

CBSE Class 10 Science Chapter 13 Revision Notes

# **Chapter 12: Electricity Revision Notes**

**Structure of the Atom**

* The nucleus of an atom is positively charged, while the electrons that orbit it are negatively charged.
* Metals' valence electrons are free to move around within the conductor, creating an electric current.

**Charge**

* Charge is a fundamental feature of matter that allows it to exert electromagnetic force.

**Insulators and Conductors**

* Conductors are substances that provide comparatively less resistance to the passage of electricity, whereas insulators provide more resistance.

**Potential Difference and Electric Potential**

* The effort done to move a unit positive charge from infinity to that location is defined as the electric potential at that place. 
* The difference in electric potentials between two points is defined as the potential difference between two points.

## **MODELS OF ELECTRIC CURRENT**

**Electric Current(I)**

* Electric current (I = Q / t) is the flow of electric charges.

**Electron sea model**

* The drift of a 'sea' of free electrons, which are free to leap onto any nearby atom, causes electric current in a solid conductor.

**Drift velocity of Electron**

* The average velocity that an electron achieves inside a metallic conductor when an electric field is applied owing to a potential difference.

**Battery and its working**

* A cell is a source of potential difference that is generated internally by chemical processes.
* At anode: Cu(s)⇌Cu2+(aq)+2e−
* At cathode: Ag(aq)+2e−⇌2Ag(s)
* The term "battery" refers to a collection of cells.

**Electric Circuit**

![circuit](//images.ctfassets.net/4yflszkpcwkt/2Y2UQfQfp6eSFP3OQ50Pfc/c03c6c33158b7e8900160a5bfd2ccd58/tech-lesson-11-5a-electricity-and-circuits-basic-electrical-circuit-diagram.jpg)
[Source: ](https://electricalacademia.com/basic-electrical/basic-electrical-circuit-theory-components-working-diagram/)
* An electric circuit is a closed-loop channel that a current follows.
* A circuit diagram is a visual representation of an electric circuit using symbols.

## **OHM’S LAW AND RESISTANCE**

**Ohm’s law**

* The applied potential difference between the two ends of an ohmic conductor is precisely proportional to the current flowing through it.

**Resistance**

* A measure of the resistance to current flow in an electric circuit is called resistance.

**Factors affecting Resistance & How they affect**

The resistance of a conductor :

* is proportional to its length.
* directly proportionate to the conductor's nature
* directly proportional to the temperature of the conductor.
* inversely proportional to the conductor's cross-sectional area

**Resistivity**

* Resistivity is the electrical resistance provided by a material of unit length and cross-sectional area.

**Ohmic and Non-Ohmic resistors**

* Ohmic resistors are those that follow Ohm's Law, whereas Non-Ohmic resistors are those that do not.

**Superconductors**

* Superconductors are conductors that have no resistance to the passage of electricity.

**Combination of Resistors**

* If two resistors carry the same current, they are said to be in series.
* When the same potential difference is applied to two resistors, they are said to be connected in parallel.

The equivalent resistance of two resistors can be calculated as follows:

In series, Req=R1+R2

In parallel, 1/Req= 1/R1+ 1/R2

**Terminal Voltage and EMF**

* When there is no current flowing through the circuit, the potential difference between the two terminals of a cell is called EMF.
* When current is flowing through a circuit, the potential difference between the two terminals of a cell is called terminal voltage. ​​

## **Heating Effect of Current**

**Joule’s Law:**

* Heat (H) ∝ square of the current (I).
* H ∝ Resistance of the given circuit.
* H ∝ Time (t) for which current flows through the conductor.
* When a potential difference is generated, electrons travel, resulting in current flow.

**Electric Power**

* Electric power is the rate at which work is completed or electrical energy is used. If W is the amount of work completed in time t, then P=W/t.
* Watt is the SI unit (W). When 1 A of current flows at a potential difference of 1 V, one watt of electricity is consumed.
* A kilowatt-hour is a commercial unit of electrical energy (kWh).
* 3.6106J = 1 kWh = 3,600,000J
* P=I2R and P=V2/R are two symbols for the same thing.
* The amount of energy consumed when 1kW of electricity is used for 1 hour is defined as one kilowatt-hour.

[Source:](https://ncert.nic.in/textbook/pdf/jesc112.pdf)

An electric circuit is a closed-loop channel that a current follows. A circuit diagram is a visual representation of an electric circuit using symbols. Friction brought the notion of electricity to light.

CBSE Class 10 Science Chapter 12 Revision Notes

# **Chapter 11: Human Eye and Colourful World Revision Notes**

* The human eye is a magnificent natural gift to the human body. The human eye has a roughly spherical shape with a diameter of 2.5 cm.

## **Human Eye Components:**
![Human eye diagram](//images.ctfassets.net/4yflszkpcwkt/45wmLSGLafHiHb0dUEnUYt/c2e6a16524d6bd439ec5e7c8fa5dd17a/eye-anatomy-700x635.jpg)
[Source: ](https://www.allaboutvision.com/resources/anatomy.htm)

* Cornea: The cornea is the eye's protective and front layer. A translucent membrane is used to create it. The cornea allows light to enter the eye.
* Iris is the name given to a dark and colourful muscular diaphragm. It is in charge of the eye's colour.
* Iris Pupil: A little circular hole at the iris's centre. It adjusts the size of the iris to control the quantity of light that enters the eye.
* Ciliary Muscles: These muscles keep the eye lens in place. The size of the eye lens is altered.
* The eye lens is a convex lens formed of a translucent jelly-like substance.
* The retina is the eye's screen. On the retina, a genuine and inverted picture form.
* Color-sensitive rods and cone-shaped cells are called rods and cones. Rods are in charge of vision in low light, whereas cones are in charge of colour perception.
* The optic nerve turns vision information into an electric signal and transmits it to the brain.
* The blind spot is the area between the optic nerve and the retina where there are no rods and cones cells. It is unaffected by light.
* Near Point: The point closest to the eye where the eye can see well without effort is referred to as the near point. It is 25 centimetres for a typical eye.
* The farthest point beyond which the eye can clearly perceive the object is referred to as the far point. It seems to be infinite to the naked eye.
* The range of vision refers to the distance between the near and distant points of the eye.

The capacity of the eye to perceive both close and far things clearly is referred to as power of accommodation.

* Nearsightedness (myopia) is a condition in which the eye is unable to view far away objects clearly but can see close objects properly.

Reason:
As the size of the eyeball grows larger,
Because to the cornea's extreme curvature,

* Due to an increase in eye lens power (or a decrease in focus length).
* It is remedied by a concave lens of appropriate focal length.
* Hypermetropia (farsightedness) is a defect in which the eye is unable to view local items clearly but can see far away objects clearly.

    Reason.
    Due to a reduction in the size of the eyeball.
    Because the eye lens's power (or focal length) has decreased.

* It is remedied by employing a convex lens with a long enough focal length.
* Dispersion of Light: Dispersion is the splitting of white light into seven colours. Consider the development of the Rainbow (VIBGYOR). The violet colour deviates the greatest, while the red colour deviates the least.
* One of the most significant and sensitive sense organs is the human eye. It allows us to view the beautiful environment and colours that surround us.
* The eyeball has a diameter of around 2.3 cm and is roughly spherical in form.
* The outer surface of the cornea is where the majority of the refraction for light rays entering the eye happens. 
* The crystalline lens only allows for finer focal length adjustments, which is necessary for focusing.

The human eye is made up of the following components:

* Cornea: The spherical translucent membrane that covers the front of the eye.
* The coloured diaphragm between the cornea and the lens is known as the iris.
* Pupil: The iris's tiny hole.
* It is a transparent lens constructed of a jelly-like substance.
* Ciliary muscles are the muscles that keep the lens in place.
* The rear surface of the eye is known as the retina.
* The place where the optic nerve exits the eye is known as a blind spot. The brain does not receive a picture created at this moment.
* Between the cornea and the lens is a clear liquid area called the aqueous humour.
* Vitreous humour: Another liquid called vitreous humour fills the gap between the eye lens and the retina.
* The picture on the retina of the eye is created by sequential refractions at the cornea, aqueous fluid, lens, and vitreous humour. The optic nerve subsequently transmits electrical impulses to the brain, where they are interpreted. The yellow area is the most sensitive to detail in excellent light, and the picture is immediately created there.
* Accommodation refers to the eye's capacity to concentrate on both near and far objects by shifting its focal length, or the ability of the ciliary muscles to modify the focal length of the eye lens.
* Eye Defects: Despite being one of the most spectacular organs in the body, the eye can have a variety of defects that can frequently be addressed with eyeglasses, contact lenses, or surgery. I Hypermetropia (long sightedness), (ii) Myopia (shortsightedness), (iii) Astigmatism, and (iv) Presbyopia are the numerous problems that can affect an eye.
* Long sightedness, also known as hypermetropia, is a condition in which a person can see far objects clearly but not adjacent items. The closest point of this flaw is more than 25 cm distant. A convex lens of appropriate power is used to treat hypermetropia (far sightedness, in which the picture of adjacent objects is focused beyond the retina). With ageing, the eye's ability to accommodate changes diminishes.
* Hypermetropia is caused by one of two factors: either the hyperopic eyeball is too short or the hyperopic eyeball is too long.
* The ciliary muscle is unable to modify the shape of the lens sufficiently to adequately focus the picture, resulting in an increase in the focal length of the eye lens.
* Myopia, often known as short sightedness or close sightedness, is a condition in which a person can see local items clearly but not far distant ones. A concave lens of appropriate power is used to rectify myopia (short sightedness, in which the picture of distant objects is focused before the retina).
* The following factors contribute to this defect: either the eyeball is longer than usual, or the lens' maximum focal length (due to excessive corneal curvature) is insufficient to generate a well formed picture on the retina.
* A person may also suffer from astigmatism, a condition in which light from a single point generates a line picture on the retina. A person with this condition is unable to see in both directions equally well, i.e., he is unable to perceive both vertical and horizontal lines at the same time. When the cornea, crystalline lens, or both are not exactly spherical, this condition occurs. Astigmatism can be remedied with cylindrical lenses that have distinct curvatures in two mutually perpendicular orientations.
* When a person suffers from both myopia and hypermetropia, bifocal lenses are used in his corrective spectacles. The upper part of the lens is concave for distance vision, while the lower half is convex for reading.
* Presbyopia is a vision problem that makes it difficult for an elderly person to read and write comfortably. Presbyopia is sometimes known as aged sight for this reason.
* An elderly person must use spectacles with a convex lens of appropriate focal length or power to correct Presbyopia, as previously mentioned.
* Hypermetropia is caused by a reduction in the length of the eyeball or an increase in the focal length of the eye lens. Presbyopia, on the other hand, is caused by an increase in the focal length of the eye lens. In Presbyopia, the eyeball is of normal length.
* The eye's eyesight deteriorates, perhaps to the point of utter blindness. Cataract surgery, or the removal of the eye lens and replacement with a lens of appropriate focal length, solves the problem.
* Because a human has a horizontal field of view of around 150° with one eye and about 180° with two eyes, we require two eyes. As a result, having two eyes gives us a greater horizontal range of view.
* The world seems flat, or two-dimensional, when viewed through one eye. The view is three dimensional with two eyes, i.e., a dimension of depth is added to our vision.
* Because our two eyes are a few millimetres apart, each sees a slightly different image. Our brain blends the two viewpoints into one, allowing us to determine the distance between the objects we perceive.
* One pair of our eyes can provide vision to two corneal blind persons if we donate them after we die. Donors of eyes might be of any gender or age. People with diabetes, hypertension, asthma, and other non-communicable illnesses are eligible to donate their eyes. People who wear spectacles or have had cataract surgery can also donate their eyes.
* The near point of the eye, also known as the least distance of distinct vision, is the shortest distance at which the eye can see objects clearly without exertion. It's roughly 25 centimetres for a young adult with normal vision.
* The picture of an item remains on the retina for 1/16 second after the thing has been removed. A movie camera's sequence of still images is displayed on a screen at a rate of roughly 24 images per second or higher. The consecutive pictures on the screen appear to blend easily into one another, giving us the sense of moving images.
* The retina of the eye has a huge number of light sensitive cells of two types: rod shaped cells that respond to light brightness or intensity, and cone shaped cells that respond to light colour. We can discriminate between distinct colours using thus/cone shaped cells.
* When a person's vision is normal but he can't distinguish between different colours, he is said to be colour blind. Color blindness is a hereditary disease that is passed down through the generations. There is currently no remedy for colour blindness.
* The far point of the eye is the furthest point beyond which a short-sighted eye can see well. The distant point is infinity for a normal eye.
* The near point of the eye refers to the farthest point to which a long-sighted eye can see well. The near point of an adult's normal human eye is roughly 25 cm from the eye.
* Least cfistance of distinct vision: The legist distance of distinct vision is the shortest distance at which an eye can see well; it is usually indicated as D. The distance between the eye and its near point is the shortest distance of clear vision. This distance is around 25 cm for a typical human eye.
* The distance between the distant and near points of the eye is referred to as the eye's range of vision.
* The violet light bends the greatest and the red light bends the least when white light passes through a prism. When white light passes through a glass prism, it splits into its seven constituent colours, which is known as dispersion. The visible spectrum is the band of seven colours acquired in this way.
* Violet, indigo, blue, green, yellow, orange, and red are the seven colours of white light. The abbreviation VIBGYOR is used to recall it.
* The first person to use a prism to get a spectrum of sunlight was Isaac Newton.
* When white light is split by a prism, we get a range of various colours called the spectrum.
* Dispersion is caused by the fact that each colour has its unique wavelength/frequency. In air/vacuum, different colours travel at the same speed. However, their speeds in refracting media like as glass differ. As a result, the refractive index of the medium varies depending on the colour. As a result, various colours pass through the prism with varying deviations. As a result, the prism emits distinct colours in different directions.
* In a vacuum, the speed of light is the same for all wavelengths, however in a solid body, the speed is variable for various wavelengths.
* Red light travels the fastest in any medium other than air/vacuum, whereas violet light travels the slowest.
* The section of the spectrum that the human eye can perceive is the most familiar kind of electromagnetic radiation. The rearranging of electrons in atoms and molecules produces light. Colors ranging from violet (= 4 x 10-7 m) to red (= 7 x 10-7 m) are used to classify visible light wavelengths. The sensitivity of the eye is a function of wavelength, with a maximum sensitivity at a wavelength of roughly 5.6 x 10-7 m. (yellow-green).
* When white light is passed through two ideptical prisms placed side by side with their refracting edges pointing in opposite directions, the first prism disperses the light into seven colours, while the second prism recombines the seven colours into white light. As a result, the light that emerges from the second prism is white.
* The dispersion of light by small droplets of water acting as prisms creates a rainbow.
* Twinkling stars, early sunrises, and late sunsets are all caused by atmospheric refraction.
* The blue colour of the sky and the reddening of the Sun at sunrise and sunset are caused by light scattering.

[Source: ](https://ncert.nic.in/textbook/pdf/jesc111.pdf)

The eye is one of the most significant and sophisticated sense organs that we have as humans. It aids in the visualisation of things, as well as light, colour, and depth perception. Furthermore, these sense organs are comparable to cameras in that they assist humans in seeing objects when light from the outside enters them.

CBSE Class 10 Science Chapter 11 Revision Notes

# **Chapter 10: Light: Reflection and Refraction Revision Notes**

**Definition of light**

* Light is an energy type that allows us to perceive things. 
* Light originates from a source and bounces off objects, which our eyes see, and our brain analyses this signal, allowing us to see.

**Nature of Light**

Light has the following properties:

* ray, such as a reflection
* interference and diffraction are examples of waves.
* photoelectric effect, for example

## **LAWS OF REFLECTION**

When light goes from one medium to another, 

* it is either absorbed or reflected (absorption) 
* comes back to life (reflection)
* bends or passes through (refraction)

When light strikes a flat mirror, the majority of it is reflected, while the rest is absorbed by the medium.

**Light's characteristics**

* Light travels at a constant speed of 2.998108m/s (roughly 3.0108m/s).

**Reflection of light by other media**

* A well-polished medium with no flaws on its surface will provide consistent light reflection. Consider a flat mirror. 
* However, some light is absorbed by the surface even then.

**Laws of Reflection**
![laws of reflection](//images.ctfassets.net/4yflszkpcwkt/1fdUZwTlyjjOH9Ke7NTqxt/c79c530229692b16fb49c2672eeff8df/1.jpg)
[Source:](https://www.geeksforgeeks.org/laws-of-reflection/)

* The normal, incident ray, and reflected ray are all in the same plane. 
* Angle of reflection = Angle of incidence

[∠i=∠r]

**Propagation of light**

* Light travels in a straight line between any two places in rectilinear propagation.
* Fermat's principle of least time may be used to justify rectilinear light propagation and the law of reflection [i=r].

**Plane mirror**

* A plane mirror is any flat and polished surface with nearly no flaws on its surface that reflect light.

**Characteristics of images**

* Real or virtual images can be upright or inverted, amplified or decreased. 
* The actual convergence of light beams creates a true picture. 
* The apparent convergence of divergent light beams is referred to as a virtual picture.
* If an image is generated upside down, it is referred to as inverted; otherwise, it is referred to as an upright image. 
* Magnified means that the picture generated is larger than the object. 
* The picture created is decreased if it is smaller than the thing.
* A planar mirror creates an image.
* A plane mirror always produces a fictitious and erect picture.
* The mirror is equidistant between the object and the image.

**The Reversibility of Light Principle**

* A beam of light will retrace its course if its direction is reversed owing to reflection off a surface.

**Spherical Mirrors**

* Consider a hollow spherical with a highly polished internal surface and a mercury-coated exterior surface that allows no light to pass through. A curved mirror, known as a spherical mirror, is created by cutting a tiny slice out of the shell.
* The focus and the radius of curvature have a relationship.
* The focal length is equal to the distance between the pole and the radius of curvature divided by two.

R/2 = F

**Curved Mirror**
![md ElWZLml9RKr3](//images.ctfassets.net/4yflszkpcwkt/1Tw84Kg60WJWFnkw8xwbhP/2802a67e7e0d763de365992ad4266156/md_ElWZLml9RKr3.png)
[Source: 
](https://www.pasco.com/products/lab-apparatus/light-and-optics/ray-optics/se-7573)

* A curved mirror is a mirror (or any polished, reflecting surface) with a curvature.
* Strictly speaking, spherical mirror is a phrase that refers to a spherical
* A spherical mirror's pole (P) is its middle.
* The spherical mirror's centre of curvature (C) was located in the centre of the sphere.
* The radius of curvature (r) is the distance between the spherical mirror and the centre of curvature. At the pole, this radius will cross the mirror (P).
* The main or primary axis is the line that passes through the pole and the centre of curvature.
* A concave mirror is a spherical mirror with an inward bulging reflecting surface.
* A convex mirror is a spherical mirror with a bulging reflecting surface.
* Take a concave mirror to focus (F). At a location halfway between the pole and the centre of curvature, all rays parallel to the primary axis converge. The focal point or focus is the name given to this place.
* Focal length is the distance between the pole and the point of focus.

**Rules of ray diagram for representation of images formed**

* When a ray passes through the centre of curvature, it collides with the concave spherical mirror, retracing its steps.
* The focal point or focus is where rays parallel to the primary axis pass through.

**Image formation by spherical mirrors**

* The image created may be discovered using the ray diagrams for the special two rays for objects in various locations. 
* The table that follows is for a concave mirror.
* Based on the picture created, a spherical mirror is used.
* Concave and convex mirrors are utilised in a variety of ways on a daily basis.
* Vehicle rearview mirrors, lighting, and solar cookers are all examples.

## **MAGNIFICATION AND MIRROR FORMULA**

**Sign convention for ray diagram**

* Distances measured in the direction of positive x and y axes (coordinate system) are positive, whereas distances measured in the direction of negative x and y axes are negative. 
* Keep in mind that the pole is the beginning (P). 
* The height of the item is usually considered as positive if it is higher than the primary axis, and the height of the picture is usually treated as negative if it is lower than the principle axis.

**Magnification and the Mirror Formula**

* 1/f = 1/v + 1/u where 'u' is the object distance, 'v' is the image distance, and 'f' is the spherical mirror's focal length, which is determined by triangle similarity.
* A spherical mirror's magnification is equal to the height of the image divided by the height of the item. 
* The letter 'm' is commonly used to symbolise it.
* The magnification formula m = h'/h = – (v/u) can be used to determine the size of a picture. It is a genuine picture if m is -ve, and it is a virtual image if m is +ve.

## **THE REFRACTIVE INDEX AND REFRACTION THROUGH THE SLAB**

**Refraction**

* The quickest road does not have to be the shortest. 
* Because light is constantly in a hurry, it bends as it passes through a new medium because it is still on the shortest path. 
* Refraction is the phenomenon of light bending in a different medium.

**The Refraction Laws**

* At the point of incidence, the incident ray, refracted ray, and normal to the interface of two transparent media all lie in the same plane.
* For a given colour of light and a given set of media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant. 
* Snell's law of refraction is another name for this law.

**Refractive Indexes, Absolute and Relative**

* The relative refractive index is the refractive index of one media in relation to another medium. 
* It's called an absolute refractive index when measured in terms of vacuum.

**Refraction through a rectangular glass slab**

* When light strikes a rectangular glass slab, it refracts laterally and emerges parallel to the incident beam. 
* It transitions from a rarer to a denser media, then back to a rarer medium.

**Refraction at a planar surface**

* When travelling from a rarer to a denser medium at the surface of the two media, light bends towards the normal, according to Snell's Law.
* When light moves from a denser to a rarer medium, it bends away from the normal at the point where the two media meet.

**Index of Refraction**

* The refractive index describes how much light bends when it moves from one material to another. 
* This is determined by the speed ratio of the two mediums. 
* The bigger the ratio, the more bending there will be. 
* It's also the constant ratio of the sine of the angle of incidence to the sine of the angle of refraction for each given set of media. 
* It's identified by:

n = sini/sinr = light speed in medium 1/light speed in medium2.

**Total internal reflection**

* When light passes from a denser medium and into a rarer medium, it bends away from the regular path. 
* The critical angle is the angle at which the incident ray causes the refracted ray to go parallel to the surface of the two media.
* When the incidence angle is larger than the critical angle, the light reflects rather than refracts inside the denser material. 
* Total Internal Reflection is the name for this occurrence.
* Mirages and optical fibres, for example.

**Lenses with a Spherical Shape**

* At curved surfaces, refraction occurs.
* The principles of refraction still apply when light strikes a curved surface and travels through it. 
* Consider the case of lenses.

**Spherical lenses**

* Spherical lenses are made by glueing together two spherical transparent surfaces. 
* Convex lenses are spherical lenses made by joining two spherical surfaces that bulge outward, whereas concave lenses are spherical lenses formed by binding two spherical surfaces that are curled inward.
* Sophisticated words for spherical lenses.
* The Optical Centre (P) of a spherical lens is the halfway or symmetric centre of the lens. The pole is another name for it.
* The line that passes through the optical centre and the centre of curvature is known as the principal axis.
* A ray that is near to the major axis while simultaneously being parallel to it is known as a paraxial ray.
* The spheres that the spherical lens was a part of have their centres of curvature (C). A spherical lens has two curvature centres.
* The focus (F) of a lens is the point on the axis where parallel rays of light converge or appear to diverge after refraction.
* Focal length is the distance between the optical centre and the point of focus.
* Diverging lens: Concave lens
* Converging lens: Convex lens

**Rules of ray diagram for representation of images formed**

* A beam of light that passes/appears to pass through the focus is parallel to the primary axis.
* A beam that passes through the optical centre has no deviation.
* Image formation by spherical lenses.

**Lens formula and magnification**

* The connection between the object-distance (u), image-distance (v), and focal length (f) of a spherical lens is given by the lens formula: 1/v = 1/u = 1/f.

**Uses of spherical lens**

* Spectacles, binoculars, magnifying lenses, and telescopes are examples of visual aids.

**Power of a Lens**

* The reciprocal of a lens' focal length, i.e. 1/f, is its power (in metre). 
* The dioptre is the SI unit of lens power (D).

[Source: ](https://ncert.nic.in/textbook/pdf/jesc110.pdf)

Light follows a straight path. When an opaque object blocks rays of light and casts a shadow on their route, this occurrence indicates that rays of light move in a straight line. When light rays strike an item, they bounce back and reach our eyes.

CBSE Class 10 Science Chapter 10 Revision Notes

# **Chapter 16: Sustainable Management of Natural Resources Revision Notes**

**Reduce, re-use, and recycle**

Each member of our society may participate in the 3 Rs to conserve the environment:

**Reduce:** We must reduce our consumption and wasteful practises. For example, avoiding wasting food, saving power by shutting off lights, replacing faulty faucets, minimising the quantity of water used for bathing, and so on.

**Reuse** is the practise of repurposing something rather than discarding them. Reusing plastic utensils and bottles, for example. Many objects can't be recycled or take a lot of energy; yet, we can put them to better use.

**Recycling** is the process of collecting waste paper, plastic, glass, or metal things in order to create new goods rather than creating them from start. It is necessary to have a system in place to separate and dispose of each sort of trash separately.

**Why is it necessary for us to manage our resources?**

* Natural resources are being drained at an alarming rate as a result of increased population and changing lifestyle demands. Management of resources must be an inherent component of our society in order to maintain a sustainable, equitable distribution of resources and the minimization of environmental harm.
* We must guarantee that we make wise use of our natural resources, which are finite and require long-term planning in order to endure generations.
* Demand for natural resources is increasing.
* As the world's population grows, so does the need for more resources, which are depleting at an exponential rate.
* Changing lifestyles and technological improvements are forcing corporations to abuse our natural resources to fulfil demand.

## **WILDLIFE AND FORESTS**

* Biodiversity hotspots are defined as forests.
* The variety and range of plant and animal life in a given ecosystem is referred to as biodiversity.
* Ecological equilibrium and ecosystem harm may be lost as a result of biodiversity loss.

**Forest stakeholders**

* When it comes to forest conservation, the following stakeholders must be considered:
* People who live in close proximity to woods and rely on forest products.
* The land and resources are owned by the government's Forest Department.

**Forest intervention by people**

* In the management of forest resources and landscapes, human intervention is required.
* To assure progress while maintaining the environment, resources must be utilised.
* To guarantee that economic progress and conservation occur at the same time, benefits must be distributed to the local population.
* Bishnoi community in Rajasthan, for example, is working to save Khejri trees in Jodhpur.

**Damage to forests and wildlife**

* Excessive and illegal logging will degrade forest resources faster than they can be replenished.
* Destroys the ecological balance and threatens the habitats of many flora and animal species.

**Sustainable development**

* Sustainable development necessitates the satisfaction of all forest resource stakeholders.
* In practise, companies use forests at considerably lower prices than the market, resulting in tensions between local residents and industrialists.
* Chipko is a Japanese movement.
* In the 1970s, the Chipko Andolan ('Hug the Trees Movement') was one such example of confrontation between industrialists and rural residents.

## **WATER**

* All terrestrial kinds of life require water to survive.
* In India, regions where there is a lack of water are also places where there is a lot of poverty.
* Despite the monsoon, there is a failure to retain groundwater due to the loss of vegetation and the discharge of industrial effluents.
* Due to the loss of the water table and the interruption of the water cycle, there is a decrease in fresh drinkable water.

**Dams**

* Dams have the ability to hold vast volumes of water while also generating energy.
* Dam mismanagement leads to exploitation, and the resource is not distributed fairly.
* Large dams have been criticised for the following reasons:

(i) Forced eviction of indigenous peoples without compensation

(ii) Corruption and money consumption without benefit generating

(iii) Environmental issues, such as deforestation

## **PETROLEUM AND COAL**

* Coal and petroleum are both fossil fuels.
* Coal and petroleum are derived from non-renewable fossil fuels. They will eventually be depleted. As a result, careful control of fossil fuel usage is critical.
* Their combustion pollutes the environment by emitting carbon, sulphur, and nitrogen oxides. As a result, we must use these resources wisely.

**Why is it important to utilize fossil fuels sparingly?**

* Fossil fuels are made up of a tremendous quantity of carbon and are generated through millions of years of decomposing vegetation.
* When they are burned in an environment with a limited supply of oxygen, they produce toxic gases that damage the climate and contribute to global warming.
* The wise use of fossil fuels improves the efficiency of our machinery and protects the long-term viability of our resources.

[Source: ](https://ncert.nic.in/ncerts/l/jesc116.pdf)

Natural resource management is the study of how the management of natural resources such as water, land, soil, animals, and plants affects the quality of life for both current and future generations. Natural resource management is concerned with the interaction of the natural landscape and people. It covers subjects such as water management, land use planning, and biodiversity protection, as well as the future viability of sectors including mining, tourism, agriculture, forestry, and fishing.

CBSE Class 10 Science Chapter 16 Revision Notes

# **Chapter 15: Our Environment Revision Notes**

**Mode of nutrition in animals and plants**

Autotrophic and Heterotrophic

**Saprophytes and decomposers**

* Plants, fungi, and microbes that feed on dead and decaying matter are known as saprophytes.
* Decomposers are organisms that break down organic materials or trash and release nutrients into the soil. 
* Bacteria, worms, slugs, and snails are examples.

**Abiotic components**

Chemical and physical components of the environment that are not living, such as soil, air, water, temperature, and so on.

**Biotic components**

Plants, animals, microorganisms, and fungus are examples of living entities in the environment.

## **ECOSYSTEM**

* Both biotic and abiotic elements are present.
* All living things, such as plants, animals, and creatures, interacting with each other and their non-living environs, such as weather, earth, sun, soil, climate, and atmosphere, in a specific region.

**Trophic levels**

* It describes the many tiers of a food web in terms of energy flow.

The various trophic levels are as follows:

* Those in charge of production (T1)
* Primary consumers (herbivores-T2)
* Secondary consumers (primary carnivores -T2)
* Tertiary consumers(Sec carnivores -T3)
* Quaternary consumers (Ter. carnivores T4)

**Decomposers**

* It might be a number pyramid, a biomass pyramid, or an energy pyramid.
* Producers are at the base of all pyramids.
* a) The number of creatures present at each trophic level is represented by a pyramid of numbers.
* It might be inverted or upright.
* b) Biomass pyramid: shows the biomass of each trophic level and can be inverted or upright.
* c) Energy pyramid: is always vertical because it depicts the flow of energy from one trophic level to the next.

**The law of energy conservation**

* Energy does neither generate or destroy itself; instead, it transitions from one form to another.
* It is transferred from one organism to the next through trophic levels in biological systems.

**Flow of energy**

* The direction and amount of energy transfer from one trophic level to another is depicted.
* The energy pyramid can be used to symbolise this.
* Only 10% of energy is transmitted from one trophic level to the next in any food chain.

**Food chain**

* A symbiotic relationship between organisms that rely on one another for nourishment.
![food chain](//images.ctfassets.net/4yflszkpcwkt/1lSYkSLnQRXMkYo3GDU8hz/c9c1ef75f01d7a9d25b7e5ad76c1133a/diagram-of-food-chain.jpg)
[source: ](https://biologyreader.com/difference-between-food-chain-and-food-web.html)
**Food web**

* It is made up of the linkages of many food chains.
* Is a graphical depiction of an ecosystem's 'Who Eats Whom'.

**Characteristics of ecosystem**

* The trophic levels are summarised.
* Their pyramids and energy flow.

**Environment**

* All living and nonliving objects are included.
* In contrast to ecosystems, there is no requirement for interaction between them.

## **POLLUTION**

**Air pollution**

* Pollutants, organic compounds, and other harmful chemicals are released into the atmosphere.

**Sources:**

* Natural occurrences such as forest fires, dust storms, and volcanic eruptions
* Power plants, residences, industry, oil refineries, and transportation are examples of man-made structures.

**Depletion of the ozone layer**

* The ozone layer shields the planet from ultraviolet (UV) radiation from the sun. 
* When CFCs are discharged into the atmosphere, they react chemically with ozone molecules, causing the layer to deplete.

**Garbage disposal**

* All of the activities and actions necessary to manage trash from its conception to final disposal are included.
* Ensures that environmental best practises, as well as necessary monitoring and regulation, are followed.

The following are the steps involved:

1. Waste segregation

2. Collection

3. Transport

4. Treatment

5. Recycling and processing

6. Disposal

**Biodegradable waste**

* Plant or animal waste is a type of waste.
* Weather, water, air, heat, microorganisms, and other natural agents decompose it into the soil.

**Biodegradation**

* Garbage or waste material decomposition by live creatures or biological processes.

It is anticipated that by the year 2030, the globe would require twice as much resources as it does now, which our earth will be unable to deliver. As a result, knowing about the environment in this century is more important than it has ever been.

CBSE Class 10 Science Chapter 15 Revision Notes

# **Chapter 14: Sources of Energy Revision Notes**

## **Why is Energy Conservation Important?**

* The capacity to conduct labour or the entire power produced from our natural resources is referred to as energy. Energy comes in a variety of forms and may be transferred from one form to another. 
* Energy in useable form is dissipated in a less useful form into the environment.
* Energy comes mostly from natural sources such as the sun, seas, fossil fuels, wind, and so on, and is turned into electrical energy that we use for our everyday requirements and advantages.

**What Constitutes a Good Fuel?**

* There are two types of energy sources: renewable and nonrenewable.
* Any source of energy that does not deplete or exhaust is regarded as a good source of energy and is referred to as renewable.

**Good fuel**

An excellent energy/fuel source would be:

* Easily accessible
* Storage and transportation are simple.
* Able to do a lot of work for a small quantity of bulk and volume
* Economical

## **THERMAL ENERGY AND FOSSIL FUELS**

**Conventional sources of energy**

* Conventional energy sources are those that have been in use for a long time or have been utilised extensively over the world. 
* For example, the use of coal following the Industrial Revolution or the use of wood as a popular source of thermal energy.
* Fossil fuels and hydropower are two examples.

**Fossil fuels**

* Fossil fuels are created by the compression of dead biological materials buried deep beneath the ground over millions of years. 
* Coal or natural gas, for example.
* For the most part, we rely largely on fossil fuels.
* Because fossil fuels are non-renewable and have finite stocks, discovering alternative energy sources is critical to avoiding an energy catastrophe.

**Disadvantages of burning fossil fuels**

* Combustion of fossil fuels also produces byproducts, which pollute the air.
* Burning coal and petroleum releases toxic carbon, nitrogen, and sulphur oxides into the atmosphere, causing acid rain and the greenhouse effect.
* The biggest contributor to global warming is gases released by the burning of fossil fuels.

**Thermal power plants**

* To create electricity, thermal power plants employ steam generated by the combustion of fossil fuels (mostly coal).
* Coal combustion warms the water, resulting in steam, which is utilised to power the turbine.
* Thermal power stations are usually built near coal or oil deposits since it is simpler to transport electricity than coal.

## **HYDROPOWER PLANT**

**Turbines**

* A turbine is a rotatory mechanical device that turns kinetic energy into usable work in various ways. 
* It converts mechanical energy into electrical energy using a dynamo.
* Various applications of this have been made in power plants where the shaft of the dynamo is mechanically rotated.

**Hydropower plants**

* The kinetic energy of flowing water or the potential energy of water falling from a height are two more classic sources of energy.
* The falling/flowing water propels the turbine, which turns mechanical energy into electrical energy with the assistance of a dynamo.
* Hydroelectric plants are often built near dams or waterfalls.

**Dams**

* A dam is a structure that keeps water or subsurface streams from flowing freely. 
* The water is evacuated when the power plant needs it to create hydroelectricity.

## **BIOMASS*

* Biomass is a renewable energy source obtained from living organisms (organic matter). 
* We used to rely on wood as a source of thermal energy for a long time. 
* We create biofuel out of biowaste such as cow dung in India since we have a large livestock population.
* The residue left behind after wood is burned in a limited supply of air and water until volatile components are eliminated is charcoal. 
* Charcoal has a high efficiency in terms of producing heat. It also doesn't have any flames.

**Bio-gas plant**

![biogas plant](//images.ctfassets.net/4yflszkpcwkt/2KBxUiYW9Oe7neANunWF4M/c5d10d32409e0b09083b5231a2550e9b/biogas-plant-techoo-01.jpg)
[Source: ](https://www.teachoo.com/12929/3533/Question-1/category/Case-Based-Questions/)

* In India, biogas is produced by decomposing cow dung, sewage waste, and plant matter in the absence of oxygen. 
* It's known as gobar gas because it contains cow manure.
* A biogas factory is a brick-built dome where cow dung and other biowaste are combined with water to make a slurry, which is then pumped into a digester.
* The digester is a sealed room that breaks down the slurry using anaerobic microorganisms.
* Methane, CO2, hydrogen sulphide, and hydrogen are released during the breakdown process.
* These gases are sucked via pipelines and sent to a turbine, which generates energy.

**WIND ENERGY**

* An energy source that is both environmentally benign and efficient.
* Wind is a natural phenomena created by pressure differentials on the earth's surface induced by uneven heating of land and sea masses. 
* Kinetic energy is the form in which it is harnessed.

**Windmill**

* Windmills are rotatory constructions that capture wind energy.
* They feature massive blades or fans installed extremely high on a strong framework that is attached to turbines that revolve and generate power owing to high wind speeds.
* Because a single windmill produces a minimal amount of energy, wind farms made up of numerous windmills are constructed.

**Wind energy's benefits and drawbacks**

Advantages: Environmentally clean, efficient, renewable source of energy with no recurrent power generation costs.

**Limitations:**

* Winds should be consistent and at least 15 km/h.
* Backup storage facilities, such as cells, are required.
* Requires a big amount of land. ​
* The initial investment is high, and maintenance is necessary on a regular basis.

## **SOLAR ENERGY**

* Solar energy is the combination of light and heat energy emitted by the sun.
* The Sun has been emitting energy for the past 5 billion years and will continue to do so for another 5 billion years or longer.
* Even though just a small percentage of solar energy reaches the earth's surface, we must discover ways to capture it as efficiently as possible.

**Solar cooker**

![solar cooker](//images.ctfassets.net/4yflszkpcwkt/2ZG5H453Dzt25DdKQIQNiZ/b052357cb3454c890590700457b9df64/solar-cooker-box-with-labels.png)
[Source: ](https://energyresearch.ucf.edu/education/k-12/resources/solar-cookers/)

* Solar energy is used to power solar cookers and water heaters.
* Solar cookers harness this feature by covering their insides black, which absorbs more energy than other surfaces.
* To focus the sun's beams, they employ reflective surfaces such as mirrors.
* By enclosing the gadget with a glass plate, the greenhouse effect is created, trapping heat inside the cooker.

**Solar cell**

* A solar cell is a device that transforms solar energy into electricity.
* A typical solar cell has a voltage of 0.5 1 V and a power output of 0.7 W. A solar panel made up of a large number of these cells can provide enough electricity for practical use.

**Advantages include:**

(i) no moving components; 

(ii) little maintenance; and 

(iii) the ability to set up in remote regions without the difficulty and expense of transmission lines.

**Disadvantages:**

(i) Requires a special quality of silicon that is difficult to come by. 

(ii) Silver is pricey because it is used for connectivity.

* Traffic lights, calculators, artificial satellites, and space missions are among examples of applications.

## **ENERGY FROM THE SEA**

* Because of the enormous volume of water and the motion of waves, the seas, oceans, and other bodies of water are a source of kinetic and potential energy.

**Tidal energy**

Tides are changes in the level of water caused by the moon's gravitational influence.

Tidal energy is created by the rise and fall of the water level, or the high and low tide.

Dams near the sea's tiny entrances are used to generate tidal energy. When the tide comes in, it pushes the turbine, which generates power immediately.

It can only be found near the sea.

**Wave energy**

* Waves contain a large amount of kinetic energy that may be used to generate power.
* Strong winds sweeping across the water cause waves to form.
* Only available in areas with high winds. This energy has been captured using devices.

**Thermal energy from the ocean**

* To harvest this sort of energy, the difference in surface temperatures of water and water at a given depth in oceans is used.
* The temperature differential between the surface and the water must be at least 20 degrees Celsius up to a depth of 2 kilometres.
* The turbine is powered by vapours created by boiling volatile ammonia in warm water. The vapour is condensed back into a liquid using cold water.

**Geothermal Energy**

* The planet has a tremendous quantity of heat trapped within it. 
* Due to geological processes, molten materials from the Earth's core occasionally rise to the surface and become trapped in hotspots. 
* Geothermal energy is the process of harnessing this heat energy.
* Any subsurface water that is present is heated by the hotspots and transformed to steam, which exits through the earth's surface as hot springs.
* This steam is utilised to create power by rotating turbines.

## **NUCLEAR ENERGY**

* Nuclear fission may be utilised to create power from nuclear energy.
* In a nuclear reactor, nuclear fuel is utilised to create energy at a regulated pace through a continuous fission chain reaction.

**Nuclear fission**

* Nuclear fission is the process of splitting a heavy atom (uranium or plutonium) into lighter nuclei by bombarding it with neutrons. 
* This process generates a great deal of energy. Fission of 1 atom of uranium, for example, produces 10 million times the energy of 1 atom of carbon from coal burning.

**Disadvantages of using nuclear energy**

* Because heavy atoms decompose into damaging subatomic particles, nuclear waste is dangerous.
* Setup and maintenance costs are high.
* Uranium is in short supply.
* It has the potential to be devastating.

**Nuclear fusion**

* Fusion is the process of fusing lighter nuclei to generate a heavier nucleus, often hydrogen or hydrogen isotopes in the case of helium.
* It generates a tremendous quantity of energy. Einstein's equation determines the mass deficit between the product and reactants. 
* E=mc2

[Source: ](https://schools.aglasem.com/ncert-books-class-10-science-chapter-14/)

Energy is the ability to do work or the total power derived from our natural resources. · Energy is mainly.derived from natural sources like the sun, oceans, waves, fossils, wind etc.

CBSE Class 10 Science Chapter 14 Revision Notes

# **Chapter 9: Heredity and Evolution Revision Notes**

**Sexual reproduction**

* The form of reproduction in which two individuals, one male and one female, reproduce together.
* They create sex cells, also known as gametes, which fuse together to form a new creature.

**Genes**

* The functional unit of heredity is the gene.
* In living creatures, each gene regulates one or more specific characteristics.

## **HEREDITY**

* Heredity is the process through which an organism's characteristics are passed down from generation to generation.
* Genes, which define the characteristics of an organism, carry out this process.

**The work of Mendel**

* Gregor Johann Mendel, sometimes regarded as the "Father of Genetics," was an Austrian monk who studied pea plants to better understand heredity.
* His research created the groundwork for current genetics.
* The Law of Dominance, The Law of Segregation, and The Law of Independent Assortment were his three primary rules of inheritance.

**Dominant traits**

* Dominant qualities are traits that manifest themselves in an organism in every possible combination and are visible.
* The tall trait in pea plants tended to express more than the short trait in Mendel's experiment.
* As a result, the plant's tall characteristic is considered to be dominant over its short trait.

**Recessive traits**

* Recessive traits are those that are not expressed in the presence of a dominant allele.
* So, if a dominant allele occurs, a recessive character/trait is present in an organism but cannot be detected.

**Monohybrid cross**

![monohybrid cross](//images.ctfassets.net/4yflszkpcwkt/G6bZdDCvnw7pGmNQnZw4p/0ddf546e994cf38b360b961892acf151/monohybrid_cross-58d567715f9b5846830d0d91.jpg)
[source: ](https://www.thoughtco.com/monohybrid-cross-a-genetics-definition-373473)

* Monohybrid crosses occur when just one character is taken into account when crossing two organisms.
* Monohybrid ratio refers to the character ratio that results from this cross at the F2 generation.
* For example, if a tall plant (TT) is crossed with a dwarf plant (tt), the F2 generation yields three tall:one short plant.
* As a result, the monohybrid ratio is 3:1.
* The plant's height is taken into account one at a time.

**Dihybrid cross**

* A dihybrid cross occurs when two characteristics are taken into account while crossing two organisms.
* The dihybrid ratio refers to the character ratio that results from this cross at the F2 generation.
* For example, if a round and green pea plant is crossed with a wrinkled and yellow pea plant, the first generation plants will all have round and green pea.
* When we cross the same for an F2 generation, we get four different character combinations in the ratio 9:3:3:1.
* As a result, the dihybrid ratio is 9:3:3:1.

**Inheritance**

* In biology, heredity is the process of passing down qualities from one generation to the next.

**Mendel's Laws**

* According to the Law of Dominance, a gene contains two opposing alleles, one of which is always expressed in the organism.
* It's known as the dominant gene, and it may be expressed in any combination.
* The Law of Segregation states that characteristics are entirely separated throughout the creation of gametes, with no allele mixing.
* The Law of Independent Assortment states that during gamete production, characteristics can segregate independently of various features.

**Sex Determination**

* Sex determination is the process of determining an individual's sex based on the genetic material's makeup.
* Various variables influence the sex of an embryo in different species.
* The presence or absence of the Y chromosome determines a person's gender in humans.
* XX is a girl, while XY is a man.
* The X chromosome is always present in an ovum.
* When an ovum fuses with Y-containing sperm, a boy is born, and when an ovum fuses with X-containing sperm, a girl is born.

**Traits**

* Traits are distinguishing characteristics of an organism that are exhibited in a visible physical form or in a physiological element of the organism.

**Speciation**

* Drift in the genetic code
* Natural selection may have a big influence on which characteristics survive in a population. Random variations in gene variants, on the other hand, have been seen on several occasions. 
* Genetic drift is the term for this phenomena. In a small population, genetic drift is defined as a change in the frequency of an existing allele.
* Genetic drift can lead to the extinction of a gene variant from the population, reducing genetic variety.

**Acquired Characteristics**

* Acquired characteristics refer to the qualities that an organism acquires throughout the course of its existence.
* These traits might be passed on to the following generation or not.

**Inherited characteristics**

* Inherited characteristics are qualities that are passed down from one generation to the next.
* These qualities are always passed on to the next generation, although they may or may not be displayed depending on dominance or recessiveness.
* Height, skin colour, and eye colour are all examples.

**Variations in genetics**

* Genetic variants are discrepancies in DNA sequences among organisms that result in a diversified gene pool. Different physical characteristics or metabolic processes result from these changes.
* Natural selection is a process that occurs in nature.
* It's the process of selecting a beneficial characteristic in a population of a species.
* All current species are under equal strain from changing ecological circumstances.
* Species/organisms that are more suited to changing conditions live and reproduce, i.e. they are selected by nature, whereas those that are unable to adapt perish, i.e. they are rejected by nature.

**Gene Flow**

* The transmission of genes from one group to the next is known as gene flow.

**Population**

* A population is a collection of animals, plants, or any living entity capable of reproducing and producing fruitful, viable offspring.

## **FOSSILS AND EVOULTION**

**Evolution**

* Evolution is the gradual change in a population's heritable features over numerous generations. These changes may result in the emergence of new species, or species may evolve to become more adapted to their surroundings.

**Fossils are proof of evolution.**

* The hypothesis of evolution is backed up by a plethora of data.
* Fossils are the largest of them all.
* The preserved remnants of ancient creatures or plants that died millions of years ago are known as fossils.
* The fossils help us comprehend the anatomy and even physiology of ancient species, as well as how evolution operated and led to the genesis of modern animals.

**Human development**

* Humans are classified as members of the ape family.
* Humans and chimps and other primates share a tight genetic link today.
* While the exact mechanism by which humans evolved from primates remains a mystery, a bigger picture of human development has emerged.
* Dryopithecus, Ramapithecus, Australopithecus, Homo erectus, Homo sapiens neanderthalensis, Cro-magnon man, and lastly us, the Homo sapiens, are some of our predecessors.
* Human evolution may be traced all the way back to Africa. Then they spread out around the globe.

[Source: ](https://ncert.nic.in/textbook/pdf/jesc109.pdf)

The transmission of qualities from parents/ancestors to children is known as heredity. Gene inheritance is how heredity is passed along. Heredity is connected to biological inheritance. Genetics is the scientific study of heredity.

CBSE Class 10 Science Chapter 9 Revision Notes

# **Chapter 8: How do Organisms Reproduce Revision Notes**

Reproduction is the process by which all creatures expand their population by multiplying in number.

## **ASEXUAL REPRODUCTION**

* Asexual reproduction is a type of reproduction in which only one organism reproduces. 
* On its own, a single creature may replicate two or more organisms. 
* All unicellular species, several multicellular organisms, and a few plants have this trait.

**Fission**

* Fission is a type of asexual reproduction seen in most unicellular organisms.
* Binary fission occurs when the fission produces two daughter cells (e.g. paramecium).
* Multiple fission occurs when fission produces a large number of daughter cells (e.g. Plasmodium).
* Distinct organisms may have different fission planes.

**Budding**

* Budding is an asexual reproduction method in which a tiny cyst-like formation forms on the parent's body, resulting in the birth of a new person.
* Buds can stay tied to their parents (yeast) or they can detach and become their own person (hydra).

**Fragmentation and regeneration**

* Regeneration is the process through which the organism regrows a lost organ or bodily component (e.g. lizard).
* Fragmentation is the process of breaking down an organism into smaller parts, each of which develops into a new organism. Planaria, Hydra, etc.

**Formation of spores**

* Fungi, for example, produce spores that can be disseminated from their fruiting body and develop into new individuals.

**Vegetative propagation**

* In plants, this is a sort of asexual reproduction.
* The plant's vegetative parts, such as leaves, stems, and roots, produce new plants.
* Artificial or natural vegetative propagation is possible.
* Leaves (e.g. bryophyllum), stems (e.g. turmeric, ginger), runners/stolons (e.g. grass runners, strawberry), bulbs (e.g. onion, lily), and so on are all examples of natural vegetative propagation.
* Cutting, grafting, layering, and plant tissue culture are examples of artificial procedures.

## **SEXUAL REPRODUCTION**

**Cell Division Types**

In eukaryotic organisms, there are two forms of cell division:

**1) Mitosis**

* It is a kind of cell division.
* It occurs in somatic cells.
* Maintains the number of chromosomes.
* Two diploid daughter cells are produced.
* Asexual reproduction, development, and growth, as well as cell replacement and regeneration, are all dependent on it.

**2) Meiosis **

* It occurs in sex cells.
* The number of chromosomes is cut in half.
* Four haploid daughter cells are produced.
* Gamete creation is required for sexual reproduction.

**Male reproductive system**

* A pair of testes is a male's primary reproductive organ.
* They generate sperm, which are male sex cells, as well as testosterone, a male sex hormone.
* Organs of male reproduction
* A pair of testes is a male's primary reproductive organ.
* Outside the body, they are found in scrotal sacs and include seminiferous tubules as the structural and functional unit.
* Seminiferous tubules create male sex cells, sperms, which develop in the epididymis.
* The hormone testosterone is secreted by Leydig cells, which are found between the seminiferous tubules.
* Male reproductive organs (accessory reproductive organs)
* Several reproductive organs that help in the process of reproduction.
* The seminal vesicles and the prostate gland are reproductive glands that produce semen and nurture sperm.
* The copulatory organ is the penis with the urethra going through it.

![Male reproductive system](//images.ctfassets.net/4yflszkpcwkt/31dSv7bILrmrpe5PCJd13J/3450577eb9652b249c51efff1253ad78/male-reproductive-system-diagram-e5d416.jpg)
[Source: ](https://www.healthdirect.gov.au/male-reproductive-system)

**Male Ducts**

* The vas deferens and the urethra are the major ducts in men.
* The vas deferens transports sperm from each testis to the urethra in a single tube.
* The urethra serves as a conduit for both sperm and urine.

**Female reproductive system**

* A pair of ovaries, a pair of fallopian tubes/oviducts, and accessory organs like the uterus and vagina make up the female reproductive system.
* The female reproductive organ is the most important organ.
* A female's major reproductive organ is a pair of ovaries.
* They make female sex cells known as eggs or ova, as well as female sex hormones known as oestrogen and progesterone.

**Female accessory reproductive organ**

* In females, the uterus and vagina are accessory reproductive organs.
* The uterus is where the foetus develops, whereas the vaginal canal gets sperm from the male.

## **MENSTRUAL CYCLE**

**Menstruation**

* When fertilisation does not occur, menstruation is the cyclic process of the ovum being released from the ovary and being removed from the body.
* The blood-rich endometrium of the uterus also breaks down during menstruation when the ovum is expelled from the body.
* LH and FSH, two pituitary hormones, and oestrogen and progesterone, two ovarian hormones, all have a role in menstruation.
* The cycle in humans repeats every 28 days.

## **REPRODUCTION IN PLANTS**

**Sexual reproduction in flowering plants**

* Flowers are used by plants to reproduce sexually.
* Flowers with essential whorls, such as androecium and gynoecium, aid in plant sexual reproduction.

**Flowers' non-essential components**

* There are necessary whorls and non-essential whorls in the typical floral structure.
* Because they do not actively participate in reproduction, Sepals and Petals are referred to as non-essential whorls.
* When in bud condition, sepals shield the inner fragile whorl and, if green in colour, also perform photosynthesis.
* When petals are coloured, they attract pollinating insects.

**Flowers' essential whorls**

![Reproduction in plants](//images.ctfassets.net/4yflszkpcwkt/1madJKn1iKE7k6Kq4Bq6Hb/a80ef4930299e432adec15d6222ab5a6/flower-anatomy-cover-image.jpg)
[Source: ](https://www.floweraura.com/blog/parts-of-flowers-flower-anatomy-101)

* The essential/reproductive whorls of a flower are referred to as androecium and gynoecium.
* Androecium generates male gametes in pollen grains, whereas gynoecium produces female gametes in ovules.
* Bisexual flowers have both whorls, whereas unisexual blooms have only one.
* A stamen is a single androecium component that consists of an anther and filament.
* Pollen grains produced by the anther are haploid.
* The stigma, style, and ovary make up each unique gynoecium component, which is referred to as a pistil.

**Pollination**

* Pollination is the process of pollen grains being transferred from anthers to the stigma of a flower.
* It is required for fertilisation.
* Self-pollination (autogamy) and cross-pollination are the two forms of pollination (allogamy).
* Pollen grains are transferred from anthers to the stigma of the same flower or another bloom of the same plant in self-pollination.
* Pollen is transmitted from anthers to the stigma of another flower in cross-pollination.
* Cross-pollination is accomplished by a variety of pollinating agents. Water, wind, insects, birds, bats, and other natural phenomena are examples.

**Fertilization**

* Fertilization is the fusion of male and female gametes.
* Pollens germinate on the stigma surface of the pistil in blooming plants following pollination and produce two male nuclei.
* Ovules have two polar nuclei and an egg cell.
* Triploid endosperm is formed when one male nucleus unites with two polar nuclei.
* Another male nucleus joins the egg cell to create the zygote, which produces the embryo and future plant.
* The ovary forms a fruit after fertilisation, and the ovules become seeds. The rest of the body wilts away.

[Source: ](https://ncert.nic.in/textbook/pdf/jesc108.pdf)

Asexual and sexual reproduction are two ways that organisms reproduce. The fusion of male and female gametes is not required for asexual reproduction. This occurs in bacteria, amoeba, hydra, and other organisms. In humans and many animals, sexual reproduction includes the union of male and female gametes.

CBSE Class 10 Science Chapter 8 Revision Notes

# **Chapter 7: Control and Coordination Revision Notes**

* Movement refers to an organism's capacity to move certain bodily components.
* It is termed locomotion when they move from one location to another.

**Introduction to control & coordination**

* Organisms respond to a variety of stimuli, including light, heat, nutrients/food, and so on.
* The neurological and endocrine systems of animals govern and coordinate all of their functions.
* Hormones are chemical messengers that help the nervous system perform a variety of tasks. Endocrine glands release these hormones.
* Hormones in plants control how they move.

## **THE NERVOUS SYSTEM**

**Neuron**
![Structure of a neuron](//images.ctfassets.net/4yflszkpcwkt/5qNySfoovnjYvx1hdBES3m/fdcd794fee29c9746dfc752c367ee7c1/20140722183828_image002.jpg)
[Source: ](https://www.topperlearning.com/answer/draw-a-labelled-diagram-of-a-neuron/j8t76t088)

* The nervous system's structural and functional unit is the neuron.
* Dendrites, cyton/soma/cell body, and axon are the three primary components of a neuron.
* Other neurons provide impulses to dendrites.
* The impulse is processed by Cyton/soma.
* The impulse is transmitted by the axon to another neuron, muscles, glands, and so on.
* Myelinated or non-myelinated axons exist.
* In myelinated neurons, impulse transmission is quicker.

**The Central Nervous System**

* The brain and spinal cord make up the central nervous system (CNS). The following are the functions of several sections of the brain:
* The cerebrum is in charge of reasoning, logic, emotions, speech, memory, visual processing, auditory and taste stimuli identification, and so on.
* The cerebellum is in charge of controlling and coordinating bodily motions, posture, and balance.
* Pons transmits information from the hindbrain to the forebrain.
* All involuntary motions such as vomiting, sneezing, yawning, heartbeat, breathing, blood pressure, and so on are controlled by the Medulla Oblongata.
* The spinal cord, which runs through the vertebral column and regulates reflex responses, continues as the medulla oblongata.

**The Peripheral Nervous System**

* The peripheral nervous system is made up of nerves that originate from the brain and spinal cord (PNS).
* Humans have 12 cranial nerves and 31 spinal nerves.

**Somatic nervous system**

* It is a component of the PNS.
* The somatic nervous system is made up of PNS nerves that govern the body's voluntary activities.

**Autonomic nervous system**

* The autonomic nervous system is made up of all of the PNS nerves that govern the body's automatic activities.
* The sympathetic and parasympathetic nervous systems are two divisions of the autonomic nervous system.
* The sympathetic nervous system, sometimes known as the fight-or-flight response, prepares the body for strong physical activity, whereas the parasympathetic nervous system has nearly the opposite effect, relaxing the body and inhibiting or slowing numerous high-energy tasks.

**Reflex action**

* A reflex action is an automatic, involuntary response of the body to stimuli.

**Reflex arc**

![reflex arc](//images.ctfassets.net/4yflszkpcwkt/5JgTxLXhIbeqb0b7lyMlVn/07d9352e863e838e2954d669107a851e/1179585_1244603_ans_145ca36637224d958ba9b95483dc1c9c.jpg)
[Source: ](https://www.toppr.com/ask/question/what-is-meant-by-reflexaction-with-the-help-of-a-labelled-diagram-trace-the-sequence/)

* During a reflex action, an electrical impulse follows this route.
* From the receptor organ to the spinal cord/brain, the impulse travels. It is processed there, and the information is then sent back to the muscle in question, which performs the action.
* The components of a reflex arc are the receptor organ, sensory/afferent neuron, interneuron, motor/efferent neuron, and effector organ.

**Protection of CNS**

Three primary layers protect the brain:

* The brittle skull (cranium)
* The cerebrospinal fluid is a fluid that surrounds the brain and spinal cord.
* The meninges are the membranes that surround the brain and spinal cord (Dura mater, Arachnoid and Pia mater).

## **CONTROL AND COORDINATION IN PLANTS**

* Plant hormones are chemicals that aid in the coordination of growth, development, and environmental reactions in plants.

Plant hormones are classified as follows: The most important plant hormones are

* Auxin: Auxin is a substance that is found in (Synthesized at shoot tip).

    Function: Assists in the development of the organism.

* Phototropism refers to the tendency of cells to grow towards the direction of light.
* Gibberellin is a hormone that aids in the development of the stem.
* Cytokinins are a kind of protein that promotes cell division.
* Abscisic acid inhibits growth and causes leaf withering. (The hormone that causes stress)

**Plant Coordination**

* Plants, unlike mammals, lack a nervous system. 
* Chemicals are used by plants to regulate and coordinate their activities. 
* Plant hormones are responsible for a wide range of plant motions. 

Tropic Movements: Tropic movements are those that are in a certain direction in reference to the stimuli. Tropic movements occur as a result of a plant part's development in a certain direction. 

Tropic motions can be divided into four categories.

**(i) Geotropic movement:** Geotropic movement refers to the development of a plant component in reaction to gravity. Roots often travel in a positive geotropic direction, meaning they grow in the direction of gravity. Negative geotropic movement is common in stems.

**(ii) Phototropic Movement:** Phototropic movement is the development of a plant component in reaction to light. Positive phototropic movement is common in stems, while negative phototropic movement is common in roots. If a plant is kept in a container that receives no sunlight but has a hole in it that allows some light in, the stem will eventually grow towards the direction of the light. This is due to a greater rate of cell division in the section of the stem that is not exposed to sunlight. The stem bends towards the light as a consequence. Increased release of the plant hormone auxin in which it is not exposed to sunlight results in a faster rate of cell division.

**(iii) Hydrotropic Movement:** When roots develop in the soil, they tend to grow toward the nearest water source. This indicates that there is a positive hydrotropic movement.

**(iv) Thigmotropism Movement:** Thigmotropism movement is the development of a plant component in reaction to contact. Climbers' tendrils show similar actions. The tendon develops in such a way that it may wrap around a support. The activity of auxin causes a difference in the rate of cell division in various areas of the tendon.

## **ENDOCRINE SYSTEM**

* Several endocrine glands make up the endocrine system. 
* Endocrine glands are ductless glands. 
* The product of the endocrine gland is immediately injected into the circulation. 
* The endocrine glands are responsible for the production of hormones. 
* Protein makes up the majority of hormones. 
* Hormones help the neurological system govern and coordinate its functions.
* Because nervous systems do not react to every portion of the body, hormones are required to alter regulation and coordination in those areas. Furthermore, hormonal control is slower than neurological control.
* Hormones are chemical messengers that are released in minute amounts by specialised tissues known as ductless glands. 
* They have an effect on target tissues or organs that are frequently far from their source. Hormones, which are chemical molecules, aid in the management and coordination of the endocrine system.
* A ductless gland that secretes hormones directly into the circulation is known as an endocrine gland.

[Source: ](https://schools.aglasem.com/ncert-books-class-10-science-chapter-7/)

Organisms travel from one location to another in response to various stimuli such as nutrition, food, water, heat, and so on. The nervous system and the endocrine system are in charge of controlling and coordinating all processes in the animal body. The Endocrine System revolves around hormones.

CBSE Class 10 Science Chapter 7 Revision Notes

# **Chapter 6: Life Processes Revision Notes**

## **NUTRITION IN PLANTS AND ANIMALS**

* Nutrition is defined as the process of getting and using food.

**Mode of nutrition:**

* Nutrition that is autotrophic (All green plants)
* Autotrophic nutrition is a type of nutrition in which an organism creates its own nourishment. 
* The autotrophic mode of nourishment is followed by green plants and blue-green algae.

**Heterotrophic Nutrition (Animals, Man, Non-green plants)**

**Heterotrophic nutrition**

* It is a type of nutrition in which one organism consumes nourishment from another organism. 
* Other than green plants and blue-green algae, all organisms feed in a heterotrophic manner. 
* Saprophytic nutrition, holozoic nutrition, and parasite nutrition are the three forms of heterotrophic nutrition.

**Saprophytic Nutrition**

* The organism secretes digestive fluids on the food in saprophytic nutrition. While the meal is still being consumed, it is being digested. 
* The creature then consumes the digested meal. 
* Saprophytic nutrition is followed by all decomposers. 
* This technique of nourishment is also used by some insects, such as houseflies.

**Holozoic Nutrition**

* In holozoic nutrition, digestion occurs within the organism's body, after the meal has been consumed. The majority of animals eat in this manner.
* Parasitic Nutrients: Parasites are organisms that live within or outside of another creature (host) and obtain nutrition from it. This sort of nutrition is known as parasitic nutrition. Cuscuta, ticks, and so forth.

**Autotrophs**

* Autotrophs are creatures that can produce their own nourishment from basic raw materials. For instance, all green vegetation.

**Heterotrophs**

* This is a type of nutrition in which organisms are unable to create their own food and must rely on others.

**Photosynthesis**

The process through which green plants create their own nourishment is known as photosynthesis.
![photosynthesis](//images.ctfassets.net/4yflszkpcwkt/5CJbfrQBlP9sNFZ9b25Vow/ad9d86216294fc24cc80fbe8d5045a11/Photosynthesis-Equation.jpg)
[Source: ](https://www.sciencefacts.net/photosynthesis.html)

**Raw materials for photosynthesis:**

* Minerals and Water: These are absorbed from the soil by the roots.
* Carbon dioxide is absorbed by the leaves through microscopic holes known as stomata.
* Solar energy is the energy emitted by the sun.
* Chlorophyll is a pigment that aids in the collection of solar energy by plants.
* Carbohydrate-glucose is transformed to starch as a result of photosynthesis.

**Symbiotic relationship**

* A symbiotic relationship occurs when two species dwell in close proximity and create a mutually beneficial interaction.
* Example, A fungus and an alga form a biological relationship known as lichen. Fungus collects water and offers shelter, while algae use photosynthesis to produce food.

**Holozoic Nutrition**

* Feeding on solid food is referred to as holozoic nutrition. The organism consumes complicated organic food. For instance, a man, an amoeba, a dog, and so on.
* Herbivores are animals that solely eat plants. For instance, a deer or a cow.
* Carnivores are animals that devour meat or flesh. Take, for example, the tiger.
* Omnivores are animals that eat both plants and meat. Take, for example, a guy and a dog.

**Holozoic nutrition consists of the following steps:**

1. Ingestion is the act of putting food into one's mouth.
2. Enzymes break down big insoluble food molecules into little water-soluble ones during digestion.
3. Digested food is absorbed into the bloodstream through the gut wall.
4. Assimilation: Absorbing food allows body cells to release energy, develop, and repair themselves.
5. Egestion is the process of removing undigested food from the body.
6. Human digestive organs include the mouth, oesophagus, stomach, small and large intestines, as well as glands such as the salivary gland, liver, and pancreas.
7. Teeth are an organ that breaks down complicated foods and aids in chewing.
8. Milk teeth are the baby's first set of 20 tiny teeth, which appear at the age of 6-7 months.
9. Permanent teeth: When a kid is 6-7 years old, the second set of 32 bigger teeth replaces the milk teeth.
10. Enamel is a protective coating on teeth that is white, robust, and gleaming.
11. Tongue: A muscular organ linked to the buccal cavity's floor that aids digestion by tasting and combining food with saliva.

## **HUMAN RESPIRATORY SYSTEM**

* A pair of lungs make up the human respiratory system. These are connected to a series of tubes that exit via the nostrils on the outside.

![human respiratory system](//images.ctfassets.net/4yflszkpcwkt/2GvIb17oHm8pffyzDObzFk/db995e5371238d8dd16073397af27bbf/respiratory-system-496x381.jpg)
[Source: ](https://www.onlinebiologynotes.com/respiration-types-of-respiration-and-anatomy-of-human-respiratory-system/)

The major components of the human respiratory system are as follows:

* **Nostrils:** A nasal channel is formed by the fusion of two nostrils. Hair lines the inside of the nostrils, which stays wet owing to mucus secretion. Mucus and hair aid in the removal of dust particles from breathed air. Furthermore, as air enters the nasal canal, it warms up.
* The **pharynx** is a tube-like structure that extends beyond the nasal canal.
* Following the pharynx is the **larynx.** This is also known as the voice box.
* The **trachea** is made up of cartilage rings. In the absence of air, cartilaginous rings keep the trachea from collapsing.
* **Bronchi:** A pair of bronchi emerge from the trachea, one bronchus for each lung.
* **Bronchioles:** Inside the lung, a bronchus separates into branches and sub-branches.
* Air sacs at the end of bronchioles are known as **alveoli.** The alveolus is a very thin membrane that serves as the opening point for blood vessels. This is the alveolus, where oxygen is mixed with blood and carbon dioxide is expelled. The pressure differential causes the exchange of gases in the alveoli.

## **TRANSPORTATION IN PLANTS AND ANIMALS**

**Plants**

* Vascular tissue is a kind of plant tissue that aids in transport.
* Xylem tissue assists plants in transferring water and minerals.
* Phloem aids in the transportation of food in plants.
* Food is transported from leaves to other regions of the plant through the process of translocation.
* Transpiration is the loss of water from a leaf's stomata.

**Animals**

* Blood is a red-colored fluid that flows throughout an animal's body.
* Plasma is a liquid component of the blood that contains nutrients, hormones, and waste products.
* Blood vessel: A tube-like structure in the body that transports blood throughout the body.
* Artery: It transports oxygenated blood from the heart to the rest of the body.
* Vein: It transports deoxygenated blood from the body's various organs to the heart.
* Capillary: A tiny tube with a thin wall that joins an artery with a vein.
* The heart is a muscular organ located in the thoracic cavity that aids in the pumping of blood throughout the body.
* A circulatory system in which blood circulates twice through the heart in a single full cycle.
* One entire contraction and relaxation of the heart is referred to as a heartbeat (72 times in a minute).
* A stethoscope is a device that monitors the rate of a person's heartbeat.
* Systolic pressure is the highest pressure at which blood flows during a cardiac contraction. (120 millimetres of mercury)
* Diastolic pressure is the lowest pressure at which blood flows when the heart is relaxing. (80 millimetres of mercury)
* Blood pressure is measured with a sphygmomanometer.
* Immunity is provided by lymph, a light yellow liquid that flows from bodily tissue to the blood circulation system.

## **EXCRETION IN PLANTS AND ANIMALS**

* The process of eliminating waste items from the body is known as excretion.
* CO2, O2, water vapour, peel of bark, fruits, leaves, gum, raisin, and other excretory products of plants
* Carbon dioxide, urea, and other excretory products of humans
* Kidney: Organ that filters blood and eliminates the harmful chemical urea.
* Urine is a yellowish liquid that is made up of both water and urea.
* Dialysis is a process for cleansing a person's blood when they have renal failure.
* Nephron: A functional unit of the excretory system that filters blood and is found in the kidney.
* Renal arteries are blood channels that carry blood from the heart to the kidneys.
* Renal Vein: A blood channel that connects the kidneys to the heart.

[Source: ](https://ncert.nic.in/textbook/pdf/jesc106.pdf)

The existence of life on Earth is primarily dependent on a set of functions and processes. Certain fundamental vital processes are required for an organism to be healthy and for the organ systems of the body to function properly. They're required for survival. Life processes are the fundamental operations that an organism does.

CBSE Class 10 Science Chapter 6 Revision Notes

# **Chapter 5: Periodic Classification of Elements Revision Notes**

**Dobereiner’s Triads**

* Dobereiner named a trio after arranging a group of three elements with comparable characteristics in order of increasing atomic masses. 
* He demonstrated that the middle element's atomic mass is about equal to the arithmetic mean of the other two. 
* However, Dobereiner was only able to determine the following three triads using the materials available at the time.

**Newlands’ Law of Octaves**

* The physical and chemical characteristics of every eighth element are comparable to those of the first when the elements are grouped according to increasing atomic masses.
* These octaves, according to Newlands, are similar to the eight notes of a musical scale.

**Limitations and Assumptions:**

1. The law applied to atoms having atomic masses between 40 and 100.

2. The properties of newly found elements did not conform to the law of octaves.

3. To accommodate components in the table, Newlands put two elements in the same position in a few situations.

4. He also put parts that were dissimilar into the same slot.

**The Periodic Table and Law of Mendeleev**

* Elements' physical and chemical characteristics follow a regular pattern based on their atomic weights.

**Mendeleev's Periodic Table Features**

* Periods are made up of twelve horizontal rows that have been shortened to seven.
* Groups are a set of eight vertical columns.
* A and B subgroups were created from Groups I through VII.
* There are no subgroups in Group VIII, and each row has three items.
* The characteristics of elements in the same group are comparable.

**Mendeleev's Periodic Table's Achievements**

1. An organised study of elements: Elements having comparable chemical and physical characteristics were grouped together to make studying their chemical and physical properties easier.

2. Atomic mass correction: The placement of atoms in Mendeleev's periodic table aided in the correction of some elements' atomic masses. The atomic mass of beryllium, for example, was changed from 13.5 to 9. Indium, gold, platinum, and other atomic masses were also rectified.

3. Prediction of attributes of yet-to-be-discovered elements: Yet-to-be-discovered elements were given the names eka-boron, eka-aluminium, and eka-silicon. The characteristics of these elements might be correctly predicted based on the properties of other elements in the same group. These elements were given the names scandium, gallium, and germanium when they were found.

4. Noble gases were found and readily placed in a new group known as the zero group of Mendeleev's table, without disrupting the previous arrangement.

**Mendeleev's Periodic Table's Limitations**

1. Hydrogen's place: Because hydrogen has qualities with both alkali metals (IA) and halogens (VIIA), Mendeleev was unable to defend its location.

2. Isotope Position: Isotopes have various atomic weights, yet they are not arranged in distinct locations in Mendeleev's periodic table.

3. Cobalt (Co) has a larger atomic weight than Nickel (Ni), however it was put before Nickel (Ni) on the periodic table.

4. Comparable elements are classified in distinct groups: Platinum (Pt) and Gold (Au) have similar qualities, yet they are placed in separate groups.

5. Periodicity's Cause: He was stumped as to what caused periodicity among the elements.

## **MODERN PERIODIC TABLE**

* The periodic function of an element's atomic number determines its physical and chemical characteristics.
* The repeating of the same outer shell electrical structure at a regular interval is the cause of periodicity.

![modern periodic table](//images.ctfassets.net/4yflszkpcwkt/6v2lov1hXwLmNQWSe0D9ZY/62d93844618ae62a5b3a898888b25912/modern-periodic-table-01---teachoo.jpg)
[Source:](https://www.teachoo.com/16962/3849/Question-1/category/Past-Year---1-Mark-Questions/)

**Periods in the Periodic Table of the Modern Era**

The number of shells present in elements from the same era is equal to the period number.

The number of electrons in the valence shell grows from one to eight as you move from left to right in a given time, but the number of shells stays the same.

**Number of Elements in a Period**

* There are just two components in the first period. The shortest duration is known as 1H and 2He.
* Short periods are the second (3Li to 10Ne) and third (11Na to 18Ar) periods, which each include eight elements.
* Long periods are the fourth (19K to 36Kr) and fifth (37Rb to 54Xe) periods, which each include 18 components.
* The sixth period, generally known as the longest period, includes 32 components (55Cs and 86Rn).
* The seventh quarter is a gap in the game.
* (The seventh period is now officially complete, thanks to recent discoveries of new elements and their insertion to the periodic table.)

**Groups in Modern Periodic Table**

* Groups are the 18 vertical columns that make up the contemporary periodic table.
* Alkali metals belong to Group 1 of the periodic table.
* Alkaline earth metals are the second group of elements.
* Pnicogens are elements that belong to Group 15.
* Chalcogens are elements that belong to Group 16.
* Halogens are elements in Group 17 of the periodic table.
* Noble gases are elements in Group 18 of the periodic table.

**Alkali Metals**

Alkali metals are the elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr) in the first group.

Because they all react with water to generate alkalis, they were given that name.

At normal temperature and pressure, the alkali metals are all lustrous, soft, and highly reactive solids that rapidly shed their outermost electron to create cations with charge +1.

The number of valence electrons is equal to one.

Alkali Earth Metals are metals that have a high alkali content.

**Alkaline earth metals** 

are the elements beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra) in the second group.

Their name comes from the fact that their oxides are naturally alkaline.

At normal temperature and pressure, they are all lustrous, silvery-white, moderately reactive hard solids. To produce cations with a charge of +2, they lose two electrons from their outermost shell.

The number of valence electrons is equal to two.

**Halogens**

* The sixteenth group of elements (F, Cl, Br, I, and As) are known as halogens and exist as diatomic molecules. 
* The letter 'X' is frequently used to refer to any halogen.
* Because they all generate a wide spectrum of salts when interacting with metals, they were given the term halogen, which comes from the Greek words Hal ("salt") and gen ("to produce").
* At room temperature, halogens exist in all three states of matter: Iodine and astatine are solids. Bromine in liquid form. Fluorine and chlorine are two gases.
* The number of valence electrons in a molecule is 7.

**Noble Gases**

* Helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn) belong to the eighteenth group of elements.
* They're all odourless, colourless, monatomic gases with negligible chemical reactivity.
* They have limited inclination to engage in chemical processes since their valence shell is deemed "full."
* Scientists thought these gases were extremely uncommon and chemically inert when they were found and classified, therefore they were given the titles 'rare' and 'inert' gases.
* The number of valence electrons is equal to eight.

## **CLASSIFICATION OF THE MODERN PERIODIC TABLE**

* Metals, non-metals, and metalloids are all categories in the contemporary periodic table.

**Metals**

* Metals are electropositive because they lose electrons to form bonds.
* Metal oxides are, in most situations, basic in nature.

**Non-metals**

* Nonmetals are electronegative because they gain electrons to form bonds.
* Non-metal oxides are acidic in nature in most circumstances.

**Metalloids**

* Metalloids and semimetals are elements that have characteristics of both metals and nonmetals.
* Boron, silicon, germanium, arsenic, antimony, tellurium, and polonium are just a few examples.

## **TRENDS IN THE MODERN PERIODIC TABLE**

* Elements in a group have the same number of valence electrons.
* The quantity of shells grows as you progress through the group.
* Elements in a period have the same number of shells.
* The number of valence shell electrons increases by one unit throughout the time.

**Variation of Valency**

* The electrical configuration may be used to compute the value of an element in two ways:
* Number of valence electrons = valency (if they are 1, 2, 3 or 4).
* The number of valence electrons is equal to the number of valence electrons (if they are 5, 6, 7 or 8).
* A group's members all have the same number of valence electrons. As a result, they have the same valency.

**Variation of Atomic Size**

* Atomic size, also known as radii, is the distance between the nucleus and the valence shell of an atom.
* The atomic radius reduces over time as the effective nuclear charge increases by one unit, attracting valence electrons or the electron cloud to the nucleus.
* Down the group — As new shells are added, the distance between the nucleus and the valence electrons or electron cloud grows.

**Variation of Metallic Properties**

* Metallic character reduces with time as the tendency to lose valence electrons decreases as nuclear charge increases.
* Nuclear pull reduces as the distance between the nucleus and the outermost electron grows. This enhances an atom's ability to lose valence electrons, resulting in an increase in metallic character.

**Variation of Nonmetallic Properties**

* As the ability to acquire electrons in the valence shell grows due to increased nuclear charge, non-metallic nature increases.
* Nuclear pull reduces as the distance between the nucleus and the valence shell rises.
* As a result, an atom's potential to gain an electron in its valence shell reduces, and its non-metallic nature decreases.

**Variation of Electronegativity**

* Electronegativity grows with time as the potential to acquire electrons in the valence shell increases as nuclear charge increases.
* Nuclear pull reduces as the distance between the nucleus and the valence shell rises. 
* This reduces an atom's potential to acquire an electron, lowering electronegativity.

[Source: ](https://ncert.nic.in/textbook/pdf/jesc105.pdf)

The periodic table is a list of all the elements known to man, arranged in order of increasing atomic number and recurrent chemical characteristics. They are arranged in a tabular format, with a row representing an era and a column representing a group. The first 94 elements of the periodic table are found in nature, but the remaining elements (numbers 95 to 118) have only been created in labs or nuclear reactors.

CBSE Class 10 Science Chapter 5 Revision Notes

# **Chapter 4: Carbon and its Compounds Revision Notes**

* Carbon is a very adaptable element. 
* Carbon is found in .02 percent in the form of minerals and .03 percent in the form of all biological structures.

**Covalent Bond in Carbon**

* Carbon has an atomic number of 6 and an electrical configuration of 2, 4. 
* It takes four extra electrons in its valence shell to achieve a noble gas structure.
* It is tough for a carbon atom to obtain or lose electrons since it is difficult to hold additional electrons and removing four electrons requires a lot of energy.
* The noble gas configuration is achieved by sharing valence electrons with other elements.
* Covalent bonding refers to the mutual sharing of electrons between atoms in order to achieve a stable noble gas structure.
* Valence electrons are shared by atoms of other elements such as hydrogen, oxygen, nitrogen, and chlorine.

Covalent bonds are classified into three categories based on the number of electron pairs shared:

* Single Covalent Bond: A single covalent bond is created when two electrons, or one pair, are shared.

Hydrogen, chlorine, and methane are three examples.

* Double covalent bond: A double bond is produced when two pairs of electrons share four electrons. 

A good example is the molecule of oxygen and the molecule of carbon dioxide.

* Triple Covalent Bond: A triple covalent bond is established when six electrons, three pairs of electrons, are shared. 

    Nitrogen (C2H2) is an example of a nutrient.

Covalently bound molecules have low melting and boiling points.

- Because no charged particles are generated, these molecules are poor conductors of electricity.

Carbon has two crucial qualities that allow it to build a huge variety of compounds.

**Catenation**

* The ability of a carbon atom to make bonds with other carbon atoms is known as catenation. 
* Silicon, like carbon, creates silanes, which are silicon compounds containing up to seven or eight hydrogen atoms.

![carbon compounds](//images.ctfassets.net/4yflszkpcwkt/3AYpKf6g68z1CnnIxTCXzB/f77af1a231476c6ac31afbd68689138c/ck_5638ec481fe5d.png)
[Source: ](https://www.meritnation.com/ask-answer/question/please-explain-in-brief-the-chains-branches-and-rings/carbon-and-its-compounds/14214751)

**Tetra Valency**

* A carbon atom with a valency of four may bind with atoms of oxygen, hydrogen, nitrogen, sulphur, chlorine, and other elements. 
* Carbon is referred regarded as tetravalent because it requires four electrons.
* Because of the smaller size of the carbon atom, the nucleus can tightly hold the shared pair of electrons, making carbon compounds particularly stable in general.

**Hydrocarbons**

* Compounds consisting mostly of hydrogen and carbon atoms.

## **SATURATED AND UNSATURATED CARBON COMPOUNDS**

**Saturated Compounds**

* Saturated compounds are hydrocarbons with single bonds between hydrogen and carbon. Alkanes are another name for them.

**Unsaturated Compounds**

* They are hydrocarbons with double or triple bonds between hydrogen and carbon. Alkenes are hydrocarbons with double covalent bonds, whereas alkynes have triple covalent bonds.

Carbon compounds are also found in cyclic form, in addition to branching forms. 

**Lewis structures (electron dot structures)** are diagrams that depict the bonding between atoms in a molecule and any lone pairs of electrons that may be present in the molecule.

The following are the steps to drawing a Lewis structure:

1. Determine how many valence (outer shell) electrons each atom in the molecule possesses.

2. In a molecule with many atom types, place the most metallic or least electronegative atom in the middle. Remember that when an atom advances away from fluorine on the periodic table, its electro-negativity diminishes.

3. Assemble the electrons such that each atom provides one electron to each atom's single bond.

4. Are the octets complete? Count the electrons around each atom. If that's the case, your Lewis dot structure is finished.

5. If the octets aren't full and extra electrons are needed, shift one electron per bond per atom to form a new bond. There will be open octets in some configurations (for example, the B in BF3), or atoms with 10 electrons (example: the S of SF5)

6. Continue with steps 4 and 5 until all octets are filled.

7. Redraw the dots such that, wherever feasible, electrons on each atom are in pairs.

![electron dot structure of propane](//images.ctfassets.net/4yflszkpcwkt/1lIBNgBxypLYe4UYWszEk8/547adc089cbad593b4e94021b1c5478b/0.png)
[Source:](https://oneclass.com/homework-help/chemistry/7028820-propane-lewis-structure.en.html) 

## **NOMENCLATURE**

* The system of assigning names to chemical substances is known as nomenclature.

**Functional Groups and Heteroatoms**

* One or more hydrogen atoms can be substituted with other atoms in a hydrocarbon chain based on their valencies. 
* A hetero atom is the element that substitutes hydrogen.
* Functional groups are made up of hetero atoms and the groups that contain them, which provide the molecule chemical characteristics.

**Homologous Series**

* It's a collection of molecules in which one functional group replaces hydrogen in a carbon chain.
* Each subsequent component differs by one -CH2 unit and 14 mass units.
* The functional group imparts chemical traits, therefore all members have comparable chemical properties. The members, however, have various morphological characteristics.
* Due to differences in molecular mass, the physical characteristics of homologous series members differ.
* With increasing molecular mass, the melting and boiling points rise. 

**Naming a carbon compound**

1. Determine how many carbon atoms are in the chemical.

2. A prefix or suffix is used to designate a functional group.

**Functional Group Suffix Prefix**

Alkene- ene

Alkyn- yne

Alcohol- ol

Aldehyde- al

Ketone- one

Carboxylic acid- oic acid

chlorine -chloro

3. If a suffix is added, the last 'e' from the name is eliminated, for example, methane-e (methan + ol).

## **CHEMICAL CHARACTERISTICS**

**Reactions of Combustion**

* Combustion is the process of converting carbon or carbon-containing substances into carbon dioxide, heat, and light in the presence of air or oxygen.

**Characteristics of the Flame**

* Unsaturated hydrocarbons produce a smoky flame, but saturated hydrocarbons provide a clear flame. 
* Even saturated hydrocarbons produce a hazy blaze when oxygen is scarce.

**Addition**

* Addition reactions occur when two molecules react to generate a single product that contains all of the combining components' atoms.
* The addition process is exemplified by the hydrogenation reaction. 
* Hydrogen is added to a double or triple bond in the presence of a catalyst such as nickel, palladium, or platinum in this reaction.

**Substitution**

* A substitution reaction occurs when an atom or group of atoms in a molecule is replaced or substituted by another atom or group of atoms. 
* Hydrogen atoms are replaced by other elements in alkanes.

CH4+Cl2+Sunlight → CH3Cl+HCl

**Ethanol**

(i) Ethanol, C2H5OH is a colourless liquid having a pleasant smell.

(ii) It boils at 351 degrees Fahrenheit.

(iii) It is miscible in all amounts with water.

(iv) It is an electrical nonconductor (it does not contain ions)

(v) It has no effect on litmus.

**Uses-**

1. As an antifreeze in automobile radiators in cold countries.

2. In the production of paints, dyes, pharmaceuticals, soaps, and synthetic rubber as a solvent.

3. As a solvent for making iodine tincture.

**What Effects Do Alcohols Have on People?**

(i) When ethanol is combined with CH3OH and ingested, it results in severe poisoning and vision loss.

(ii) It induces addiction and harms the liver if used in large quantities.

(iii) Excessive ethanol drinking can result in death.

**Ethanol Reactions with Sodium**

When ethanol interacts with sodium, hydrogen gas and sodium ethoxide are produced. The acidic nature of ethanol is supported by this reaction.

2C2H5OH+2Na → 2C2H5ONa+H2

(↑)

**Reaction of Elimination**

* A sort of reaction in which two substituents are eliminated from a molecule is known as an elimination reaction. 
* In the preparation of alkenes, these reactions are crucial.

**Reaction to Dehydration**

* At 443 K, ethanol combines with concentrated sulphuric acid to form ethylene. 
* Because a water molecule is removed from the ethanol molecule during this process, it is called dehydration of ethanol.

CH3CH2OH → CH2=CH2+H2O

(The reaction occurs in the presence of Conc.H2SO4)

**Ethanoic acid (ethanol) or acetic acid (acetic acid)**

(i)  Molecular formula: CH3COOH

(ii) It is water, alcohol, and ether soluble.

(iii) Because it freezes often during the winter in frigid climates, it is known as glacial acetic acid.

**Esterification**

* A sweet-smelling ester is generated when a carboxylic acid is refluxed with alcohol in the presence of a little amount of conc.H2SO4. 
* Esterification is the process of forming an ester.

**Saponification**

* A sodium or potassium salt of long-chain carboxylic acids is referred to as soap (fatty acid). 
* RCOONa is a general representation of the soap molecule, with R denoting the non-ionic hydrocarbon group and COONa+ denoting the ionic group. 
* Hydrolysis of fat occurs when oil or fat of vegetable or animal origin is treated with a strong sodium or potassium hydroxide solution, resulting in soap and glycerol formation. 
* Saponification is the term for the alkaline hydrolysis of oils and fats.

Source: 

Carbon compounds can be found in everything, including the food we consume, the clothes we wear, and even the lead of the pencil we use to write. It may be found in both the free and combined states. It can be found in the elemental condition as coal or graphite. In its combined condition, it exists as metal carbonates, hydrocarbons, and carbon dioxide gas. When it reacts with other elements like dihydrogen, dioxygen, chlorine, and sulphur, it creates a wide range of compounds ranging from tissues to pharmaceuticals.

CBSE Class 10 Science Chapter 4 Revision Notes

# **Chapter 3: Metals and Non- metals Revision Notes**

**Alloys**

* Alloys are homogenous metal-to-metal or metal-to-nonmetal combinations. Alloy formation improves the material's desired qualities, such as hardness, tensile strength, and corrosion resistance.

A few examples of alloys:

Brass is made up of copper and zinc.

Bronze is made up of copper and tin.

Lead and tin solder

Amalgam is a mixture of mercury and other metals.

**Corrosion**

* The action of moisture, air, or chemicals in the surrounding environment causes gradual degradation of a substance, generally a metal.
* Rusting:

4Fe(s)+3O2(from air)+xH2O(moisture)→2Fe2O3. xH2O(rust)

* Copper corrosion is a type of corrosion that occurs when copper is exposed to air.

Cu(s)+H2O(moisture)+CO2(from air)→CuCO

* Silver corrosion is a term used to describe the process of a metal corroding.

Ag(s)+H2S(from air)→Ag2S(black)+H2(g)

**Prevention of Corrosion**

1. Painting, oiling, or greasing metal surfaces: Painting, oiling, or greasing metal surfaces keeps air and moisture out.

2. Alloying: Alloyed metal is more corrosion resistant. Take, for example, stainless steel.

3. Galvanization: This is the process of coating iron items with molten zinc. Zinc inhibits corrosion by forming a protective coating.

4. Electroplating: Electroplating is a technique for coating one metal with another using an electric current. This procedure not only protects the metal, but it also improves its beauty.

Silver plating and nickel plating are two examples.

5. Magnesium is more reactive than iron, hence it serves as a sacrificial shield. When coated on iron or steel items, it works as a cathode, undergoing reaction (sacrifice) in place of iron and protecting the materials.

## **PHYSICAL PROPERTIES**

**Physical Properties of Metals**

● Hard and have a high tensile strength

● Solid at room temperature

● Sonorous

● Good conductors of heat and electricity

● Malleable, i.e., can be beaten into thin sheets

● Ductile, i.e., can be drawn into thin wires

● High melting and boiling points (except Caesium (Cs) and Gallium (Ga))

● Dense, (except alkali metals). Osmium – highest density and lithium – least density

● Lustrous

● Silver-grey in colour, (except gold and copper)

**Non-Metals**

Nonmetals are elements that don't have the same characteristics as metals.

**Physical Properties of Non- Metals**

* At room temperature, they exist as solids, liquids, and gases.
* Brittle
* Non-malleable
* Non-ductile
* Non-sonorous
* Heat and electricity conductors that aren't up to par

**Physical Properties with Exceptions**

* Knives can be used to cut alkali metals (Na, K, and Li).
* Mercury is a metal that is liquid at room temperature.
* Heat conductivity is weak in lead and mercury.
* The slightest change in temperature causes mercury to expand dramatically.
* The melting points of gallium and caesium are quite low.
* Iodine is a non-metallic substance with a lustrous sheen.
* Graphite is a material that conducts electricity.
* Diamond is a heat conductor with a high melting point.

## **CHEMICAL PROPERTIES**

**Chemical Properties of Metals**

* Alkali metals (Li, Na, K, and so on) have a strong reaction with water and oxygen or air.
* When Mg comes into contact with hot water, it reacts.
* Steam reacts with Al, Fe, and Zn.
* Water and dilute acids do not react with Cu, Ag, Pt, or Au.

**Reaction of Metals with Oxygen (Burnt in Air)**

* Metal + Oxygen Metal oxide is a combination of metal and oxygen (basic)
* Because Na and K react violently with air and catch fire, they are maintained submerged in kerosene oil.

4K(s)+O2(g)→2K2O(s) (vigorous reaction)

Mg, Al, Zn, and Pb react slowly with air and produce a corrosion-resistant coating.

2Mg(s)+O2(g)→2MgO(s) (Mg burns with white dazzling light)

4Al(s)+3O2(g)→2Al2O3(s)

Silver, platinum, and gold are inert metals that do not burn or react with air.

**Basic Oxides of Metals**

* Alkalis are formed when metallic oxides dissolve in water. Their aqueous solution changes from red to blue litmus.

Na2O(s)+H2O(l)→2NaOH(aq)

K2O(s)+H2O(l)→2KOH(aq)

**Metal Amphoteric Oxides**

* Amphoteric oxides are metal oxides that create salt and water when they react with acids and bases.

Al2O3, ZnO, PbO, and SnO are other examples.

Al2O3(s)+6HCl(aq)→2AlCl3(aq)+3H2O(l)

Al2O3(s)+2NaOH(aq)→2NaAlO2(aq)+H2O(l)

ZnO(s)+2HCl(aq)→ZnCl2(aq)+H2O(l)

ZnO(s)+2NaOH(aq)→Na2ZnO2(aq)+H2O(l)

## **EXTRACTION OF METALS**

**Manufacturing of steel**

Thermite reaction: Al(s)+Fe2O3(s) → Al2O3+Fe(molten)

Welding of railway tracks, fractured machine components, and other applications employ the thermite reaction.

**Metals' Occurrence**

* The majority of elements, particularly metals, exist in nature in combination with other elements. Minerals are made up of all of these metal compounds. However, only a handful of them are viable suppliers of that metal. Ores are the name for such sources.
* Au, Pt – can be found in their natural or unprocessed condition.
* Ore enrichment is a term used to describe the process of enriching ore.
* It refers to the physical and chemical techniques used to remove impurities or gangue from ore. The process utilised for a certain ore is determined by the differences in the ore's and gangue's qualities.

Metal Refining is a process that involves the refinement of metals.

Metal refining is the process of eliminating impurities and gangue from raw metal. It is the final phase in metallurgy and is based on the differences in metal and gangue characteristics.

**Refining by Electrolysis**

![Electrolysis](//images.ctfassets.net/4yflszkpcwkt/6UYB9xAQe4hBVYqVGvBi6d/c55e7a34db4b32b0e2e2783ae6e02c23/31622_b990e75fa55b4318ad8260336b3272b3.png)
[Source:](https://www.toppr.com/ask/content/concept/products-of-electrolysis-260645/)

* Copper, zinc, nickel, silver, tin, gold, and other metals are purified electrolytically.
* Impure or unrefined metal is used as an anode.
* A thin strip of pure metal is used as a cathode.
* Aqueous solution of metal salts is used as an electrolyte.
* Metal ions are discharged into the solution from the anode (oxidation).
* The corresponding quantity of metal from the solution is deposited at the cathode (reduction).
* Impurities collect near the anode's bottom.
* Compounds with an ionic charge
* The complex is held together by electrostatic interaction between the oppositely charged ions.
* MgCl2, CaO, MgO, NaCl, and other salts are examples.

**Ionic Compound Properties**

* Usually, they're crystalline solids (made of ions).
* Melting and boiling points are quite high.
* When melted and in aqueous solution, they conduct electricity.
* Water and polar solvents are the most common solubilizers.

**Ionic Compounds and Electric Conduction**

* When ions become free and function as charge carriers in a molten or watery state, ionic compounds transmit electricity.
* Ions in solid form are kept in place by electrostatic forces of attraction and are thus unable to conduct electricity since they are not free to move.

[Source: ](https://schools.aglasem.com/ncert-books-class-10-science-chapter-3/)

Metals are malleable and ductile elements that conduct heat and electricity. Iron (Fe), Aluminum (Al), and Silver (Ag) are among examples (Ag). Metals may be found in abundance in the earth's crust. Minerals are elements or compounds that exist naturally in the earth's crust.

CBSE Class 10 Science Chapter 3 Revision Notes

# **Chapter 2: Acids, Bases and Salts Revision Notes**

**Classification of Matter**

on the basis of

a) Composition– elements, compounds, and mixes

b) State of matter- Solids, liquids and gases

c) soluble matter – suspensions, colloids, and solutions

* Homogeneous and heterogeneous mixes are two types of mixtures.
* Covalent and ionic compounds are two different types of chemicals.

## **What Is the Difference Between an Acid and a Base?**

**Physical examination**

There are two physical tests that may be used to determine if an acid or a base is present.

**a. Taste**

* An acid has a sour flavour, whereas a base has a bitter flavour.
* Because an acid or a base might be polluted or caustic, this way of tasting is not recommended.

**b. Effect on Indicators by acids and bases**

* When a chemical substance comes into touch with an acid or a base, it changes its physical qualities, most commonly colour or scent.

The following are some regularly used indicators and the many colours they display:

**a) Litmus paper**

* Purple in a neutral solution
* In an acidic solution, the colour is red.
* Blue is the most basic answer.
* Litmus is also available as paper strips in two colours: red and blue litmus.
* A damp blue litmus paper turns red when exposed to an acid.
* A base changes the colour of wet red litmus paper to blue.

**b) Methyl orange**

* Orange in a neutral solution
* In an acidic solution, the colour is red.
* Yellow in basic solution

**d) Phenolphthalein**

* In a colourless neutral solution
* In an acidic solution, the substance stays colourless.
* Pink is the most basic answer.

## **WATER**

* Water contains acids and bases.
* Acids and bases breakdown into their respective ions when introduced to water and aid in the conductivity of electricity.

**What is the distinction between a base and an alkali?**

* Acids react with bases to neutralise them.
* Metal oxides, metal hydroxides, metal carbonates, and metal bicarbonates make up these compounds.
* The majority of them are water insoluble.
* An alkali is a base in aqueous solution (mainly metallic hydroxides).
* It dissolves in water and then dissociates to produce the OH ion.
* All bases are alkalis, but not all alkalis are bases.

**Hydronium ion**

* A coordinate covalent bond is created when a hydrogen ion receives a lone pair of electrons from the oxygen atom of a water molecule.

**Dilution**

* Dilution is the process of decreasing a solution's concentration by adding more solvent (typically water).
* It's a really exothermic reaction.
* Acid must be put to water, not the other way around, to dilute it.

## **STRENGTH OF ACID AND WATER**

* When all molecules of an acid or a base disintegrate entirely in water to produce their corresponding ions, H+(aq) for acid and OH(aq) for base).

Weak acid or base: When just a few molecules of an acid or base dissociate in water to produce their corresponding ions, H+(aq) for acid and OH(aq) for base.

**Universal Indicator**

* The pH range of a universal indicator is 0 to 14, and it represents the acidity or alkalinity of a solution.
* The pH of a neutral solution is 7.

## **pH**

* The pH scale spans from 0 to 14, with 0 being the most acidic and 14 being the most alkaline.
* If the acidic solution has a pH of 7, it is said to be acidic.
* If the pH is more than 7, use a basic solution.

**Importance of pH in everyday life**

**1. Plant and animal pH sensitivity**

* pH affects both plants and animals. At a given pH value, vital life activities such as food digestion, enzyme functioning, and hormone production take place.

**2. A soil's pH**

* The pH of a soil that is ideal for plant or agricultural growth is 6.5 to 7.0.

**3. The digestive system's pH**

* In human stomach, digestion takes place at a precise pH range of 1.5 to 4.
* HCl in our stomach influences the pH of enzyme interactions as food is being digested.

**4. The role of pH in tooth decay**

* When the teeth are exposed to an acidic environment with a pH of 5.5 or lower, tooth decay occurs.

**5. The pH of animal and plant self-defense**

* Animals and plants employ acidic compounds as a self-defense strategy. 
* For self-defense, bees and plants like nettle emit a very acidic chemical. These acidic chemicals released have a specified pH.

## **SALTS**

* A salt is a compound made up of an acid's anion and a base's cation.
* KCl, NaNO3, CaSO4, and other salts are examples.
* The neutralisation reaction of an acid and a base is commonly used to make salts.

![formation of salt](//images.ctfassets.net/4yflszkpcwkt/2wUH3wCHYIZqWS34MraAfB/d3d2edd11e1658fbfb185a6609e8a279/neutralisations.jpg)
[Source: ](https://www.successcds.net/class10/science/acids-bases-salts.html)

**Common salt**

* Because it is used in cooking all around the world, sodium chloride (NaCl) is known as common salt.

**Family of Salt**

* Salts with the same cation or anion are classified as belonging to the same family. NaCl, KCl, and LiCl, for example.

**The salts' pH**

* In nature, a salt comprising a strong acid and a strong base will be neutral. pH 7.0 (approx.).
* In nature, a salt of a weak acid and a strong base will be basic. pH greater than 7.
* Acidic in nature is a salt comprising a strong acid and a weak base. pH is less than 7.
* A pH test is used to detect the pH of a salt of a weak acid and a weak base.

**Bleaching powder**

* Bleaching powder produces chlorine when it comes into contact with water, which is responsible for the bleaching effect.

**Baking soda**

* Sodium hydrogen carbonate is the chemical name for this substance.
* NaHCO3 is the chemical formula.

Uses:

1. Textile manufacturing

2. Paper manufacturing

3. Antiseptic

**Washing soda**

* Sodium hydrogen carbonate is the chemical name for this substance.
* NaHCO3 is the chemical formula.

**Preparation (the Solvay method) –**

a. Limestone is heated in the following way: CaCO3 + CaO + CO2

b. CO2 is passed through a concentrated sodium chloride/ammonia solution:

NaHCO3(aq) + NH4Cl = NaCl(aq) + NH3(g) + CO2(g) + H2O(l) (aq)

Uses

In the glass, soap, and paper industries, for example.

2. Water softening

3. A housecleaner

**Plaster of paris**

* Heating gypsum, CaSO4.2H2O (s) to 100°C (373K) yields CaSO4. 12 H2O and 3/2 H2O.
* Plaster of Paris is made up of CaSO4 and 12 H2O.
* CaSO4. 12 H2O denotes that two CaSO4 formula units share one water molecule.
* Casts are used to help mend fractures.

[Source: ](https://ncert.nic.in/textbook/pdf/jesc102.pdf)

A chemical substance's characteristics alter when it comes into touch with an acid or a base. In this chapter, the changes in substance are examined in depth.

CBSE Class 10 Science Chapter 2 Revision Notes

# **Chapter 1: Chemical Reactions And Equations Revision notes**

**Changes in physical and chemical properties**

* **Chemical change -** the formation of one or more new compounds with different physical and chemical characteristics.
* **Physical change -** the colour or condition of the substance changes, but no new substance is generated.

Any of the following observations can be used to determine a chemical reaction:

a) A gas's evolution

b) Thermodynamic shift

d) Precipitation formation

d) A colour change

e) State transition

## **CHEMICAL REACTIONS**

* Chemical reactions are transformations of reactants into products through the formation or breaking of bonds (or both) between distinct atoms.

**Equation of words**

* A chemical reaction represented in words rather than scientific formulae is known as a word equation. In a chemical reaction, it aids in the identification of the reactants and products.
* As an example, "Sodium interacts with chlorine to generate sodium chloride.

**Elements' symbols and their valencies**

* An element's chemical code is represented by a symbol. Each element has a one- or two-letter atomic symbol that is an abbreviated version of its name.
* An element's valency is its ability to combine with other elements. It is the number of electrons that an atom loses, gains, or shares as it joins with another atom to create a molecule.

## **WRITING CHEMICAL EQUATIONS**

* A chemical equation is a representation of a chemical process using symbols and chemical formulae for the reactants and products.
* The symbol for solids is "(s)".
* It's "(l)" for liquids.
* It's "(g)" for gases.
* It's "(aq)" for aqueous solutions.
* "(upward facing arrow)" is used to symbolise the gas created during the reaction.
* "(downward facing arrow)" is used to symbolise the precipitate generated during the reaction.

## **BALANCING CHEMICAL REACTIONS**

* Mass conservation is important.
* Because no atoms may be formed or destroyed in a chemical reaction according to the rule of conservation of mass, the number of atoms for each element in the reactants side must equal the number of atoms in the products side.
* To put it another way, the total mass of the products generated in a chemical reaction is equal to the total mass of the reactants involved.

**Balanced Chemical Equations**

* A balanced chemical equation is one in which the number of atoms of each element in the reactants side equals the number of atoms in the products side.
* Chemical equations are balanced using the following steps.
* Change the coefficients (the numbers in front of the compound or molecule) while balancing the equation so that the number of atoms of each element is the same on both sides of the chemical equation.

## **TYPES OF CHEMICAL REACTIONS**

Chemical reactions are classified into several groups based on a variety of characteristics.

Here are a few examples:

● Combination

● Decomposition

● Single Displacement

● Double displacement

● Redox

● Endothermic

● Exothermic

● Precipitation

● Neutralisation

**Combination reaction**
![Example of combination reaction](//images.ctfassets.net/4yflszkpcwkt/18zNzpEVxk0T6EbUvfuyYG/dbe7f2bf1e210bc1f14647b796bc85f6/shutterstock389052655w400.jpg)
[Source: ](https://www.yaclass.in/p/science-cbse/class-10/chemical-reactions-and-equations-11516/re-757f4594-4d92-44f0-8059-4c211e9d1220)

* Two elements or one element and one compound or two compounds combine to form a single product in a combination reaction.

**Decomposition reaction**

* When heat, light, or electricity is applied to a single reactant, it decomposes into two or more products.

**Displacement reaction**

* A less reactive element is displaced from its compound or solution by a more reactive element.

**Double displacement reaction**

* To produce new products, ions are exchanged between the reactants.

**Precipitation reaction**

* When two solutions containing soluble salts are mixed, an insoluble substance called precipitate occurs.

**Redox reaction**

* Oxidation and reduction happen at the same time.
* Oxidation is the process through which a substance loses electrons, receives oxygen, or loses hydrogen.
* Reduction is the process of a substance gaining electrons, losing oxygen, or gaining hydrogen.
* A compound that oxidises another material and then reduces itself is known as an oxidising agent.
* A reducing agent is a chemical that oxidises itself after reducing another molecule.

**Endothermic and Exothermic reactions**

* An exothermic reaction is one in which heat is released as a result of the reaction. Exothermic reactions characterise the majority of combination reactions.

Al2O3 + Fe + heat Al2O3 + Fe + heat

CO2 + 2H2O + heat = CH4 + 2O2

The reaction is endothermic, which means it requires heat to complete.

C6H12O6 + 6O2 = 6CO2 + 6H2O + Sunlight

The majority of breakdown processes are endothermic in nature.

**Corrosion**

* Degradation of a substance, generally a metal, over time due to the action of moisture, air, or chemicals in the environment.
![Corrosion](//images.ctfassets.net/4yflszkpcwkt/a3yVVcw9hiEvebk53Qq73/9d28c6ecf1618f1678b454db19c7f40b/image024.png)
[Source:](https://ncerthelp.com/query1.php?Q=ncert+solutions+class+12+Chemistry+Chapter+3+ELECTROCHEMISTRY)

2Fe2O3.xH2O = 4Fe(s) + 3O2(from air) + xH2O(moisture) (rust)

Copper corrosion is a type of corrosion that occurs when copper is exposed to air.

CuCO3.Cu(OH)2 = Cu(s) + H2O(moisture) + CO2(from air) (green)

Silver corrosion is a term used to describe the process of a metal corroding.

Ag(s) + H2S (from the air) = Ag2S(black) + H2S (from the air) (g)

**Rancidity**

* It is the oxidation of fats and oils in food that has been stored for a lengthy period of time. 
* It gives food a terrible odour and an unpleasant flavour. When you eat rancid food, you get a stomach illness.

__Prevention:__

Containers that are airtight

Nitrogen-filled packaging

Refrigeration

Antioxidants or preservatives are added

[Source: ](https://schools.aglasem.com/ncert-books-class-10-science-chapter-1/)

Chemical Reaction is the process of transforming a chemical substance into a new chemical substance by forming and breaking connections between various atoms.