Let x and x + 8 be the two parallel sides of the trapezium. Then,

\(\frac{1}{2}\times(x +x+8)\) x 24 = 312 ⇒ 2x + 8 = 26 ⇒ 2x = 18 ⇒ x = 9

∴ The two parallel sides are 9 m and 17 m. 

Given radius of the ring r = 7 cm 

Circumference of the ring C = 2πr 

= 2 x \(\frac{22}{7}\) x 7 = 44 cm 

Length of rod required to make one ring = 44 cm 

Length of rod required to make 70 rings 

= 44 x 70 = 3080 cm 

Wastage = 20 cm 

Required length of rod to make 70 rings = 3080 + 20 = 3100 cm

Correct option is A) 44cm

Given radius of circle is r = 7 cm

\(\therefore\) Circumference of circle is P = 2πr = 2 x 22/7 x 7

 = 44 cm

Correct answer is (c) 52 cm²

Area of trapezium = \(\frac{1}{2}\) (Sum of parallel sides) x Distance between them

= \(\frac{1}{2}\times \)(9.7 + 6.3) x 6.5

= 8 x 6.5

= 52.0 cm²

Area of the trapezium = \(\frac{1}{2}\times \) (sum of the parallel sides) x distance between the parallel sides

= \(\frac{1}{2}\times(12+9)\times8\)

= 21 x 4

= 84 cm²

So, the area of the trapezium is 84 cm².

∆ABC is an equilateral triangle the length of whose side is equal to 10 cm, and ∆DBC is right-angled at D and BD = 8 cm.

From figure:

Area of shaded region = Area of ABC – Area of DBC …..(1)

Area of △ABC:

Area = √3/4 (side)² = √3/4 (10)² = 43.30

So area of △ABC is 43.30 cm²

Area of right △DBC:

Area = 1/2 x base x height …(2)

From Pythagorean Theorem:

Hypotenuse² = Base² + Height²

BC² = DB² + Height²

100 – 64 = Height²

36 = Height²

or Height = 6

equation (2) =>

Area = 1/2 x 8 x 6 = 24

So area of △DBC is 24 cm²

Equation (1) implies

Area of shaded region = 43.30 – 24 = 19.30

Therefore, Area of shaded region = 19.3 cm²

Let x cm be the one of the sides, then (x – 2) cm be another side.

Area of triangle = 24 cm² (given)

We know, Area of triangle = 1/2(Base x height)

24 = 1/2(x (x – 2))

48 = x² – 2x

or x² – 2x – 48 = 0

Solving above equation, we have

(x + 6)(x – 8) = 0

x = -6 or x = 8

Since length measure cannot be negative, so neglect x = -6

One side = 8 cm

Another Side = x – 2 = 8 – 2 = 6 cm

Apply Pythagoras theorem:

Hypotenuse² = Base² + Perpendicular²

Hypotenuse² = √(8² + 6²)

Hypotenuse = √100 = 10

Therefore, perimeter of triangle = Sum of all the sides = (6 + 8 + 10) cm = 24 cm

Let x cm be the one of the sides, then (x – 7) cm be another side.

Area of triangle = 60 cm² (given)

We know, Area of triangle = 1/2(Base x height)

60 = 1/2(x (x – 7))

120 = x² – 7x

or x² – 7x – 120 = 0

Solving above equation, we have

(x – 15)(x + 8) = 0

x = 15 or x = -8

Since length measure cannot be negative, so neglect x = -8

One side = 15 cm

Another Side = x – 7 = 15 – 7 = 8 cm

Apply Pythagoras theorem:

Hypotenuse² = Base² + Perpendicular²

Hypotenuse² = √(15² + 8²)

Hypotenuse = √289 = 17

Therefore, perimeter of triangle = Sum of all the sides = (15 + 8 + 17) cm = 40 cm

The perimeter of a right triangle = 40 cm

Hypotenuse measures = 17 cm.

Let x and y are the another sides.

40 = 17 + x + y

x + y = 23

or y = 23 – y

So, we have 3 sides as x, 23-x and 17.

Apply Pythagoras theorem:

Hypotenuse² = Base² + Perpendicular²

17² = x² + (23-x)²

289 = x² + 529 + x² – 46x

x² – 23x + 120 = 0

(x – 8)(x – 15) = 0

x = 8 or x = 15

If x = 8 then y = 23-8 = 15

If x = 15 then y = 23-15 = 8

Now,

Area of triangle = 1/2 × base × height

= 1/2 × 8 × 15

= 60

Therefore, Area of triangle is 60 cm²

Perimeter of triangle = 150 m (given)

Let the sides of triangle be, a, b and c,

On dividing 150 m in the ratio 5 : 12 : 13, we get

a = 5x cm

b = 12x cm

c = 13x cm

We know that, Perimeter of a triangle = Sum of all the sides = a + b + c

150 = 5x + 12x + 13x

= 30 x

x = 5

Sides are:

a = 5x = 25 cm

b = 12x = 60 cm

c = 13x = 65 cm

Now,

 Let a, b and c be the sides of a triangle.

Apply Heron's Formula to find the area of triangle.

Area = \(\sqrt{S(S-a)(S-b)(S-c)}\)

Where S = \(\frac{a + b + c}{2}\)

S = 1/2(25+60+65) = 75 cm

Area = √(75(75-25)(75-60)(75-65))

= √(75 × 50 × 15 × 10)

= 750

Area of triangle is 750 cm².

Given,

Base = 1.2 m

Hypotenuse = 3. 7 m

Height =?

By Pythagoras theorem, we have

Hypotenuse² = Base² + Height²

Height² = Hypotenuse² – Base²

Height² = 3.7² – 1.2²

Height² = 13.69 – 1.44

Height² = 12.25

Height = √12.25

Height = 3.5 m

Then,

Area of right triangle = (1/2) × base × height

= (1/2) × 1.2 × 3.5

= 0.5 × 1.2 × 3.5

= 2.1 m²

Let the length of the other side be h cm.

Then, area of the triangle = (1/2) × base × height

129.5 = (1/2) × 14.8 × h

129.5 = 1 × 7.4 × h

129.5 = 7.4h

h = 129.5/7.4

h = 17.5 cm

Hence, the length of the other side is 17.5 cm

Perimeter of triangle = 540 m

Let the sides of triangle be, a, b and c

On dividing 540 m in the ratio 25:17:12, we get

a = 25x m

b = 17x m

c = 12x m

We know that, Perimeter of a triangle = Sum of all the sides = a + b + c

540 = 25x + 17x + 12x

= 54 x

x = 10

Sides are:

a = 25x = 250 m

b = 17x = 170 m

c = 12x = 120 m

 Let a, b and c be the sides of a triangle.

Apply Heron's Formula to find the area of triangle.

Area = \(\sqrt{S(S-a)(S-b)(S-c)}\)

Where S = \(\frac{a + b + c}{2}\)

S = 1/2(250+170+120) = 270 m

Area = √(270(270-250)(270-170)(270-120))

= √(270 x 20 x 10 x 150)

= 9000

Area of triangle is 9000 m².

Now,

The cost of ploughing 100 m² = ₹40

The cost of ploughing 1 m² = ₹ 40/100

Therefore, cost of ploughing 9000 m² = 9000 x 40/100 = ₹3600

 The Class 12 Physics MCQ Questions with Answers can be easily accessible on Sarthaks eConnect. Students Class 12 Physics MCQ Questions of Electrostatic Potential and Capacitance with Answers provide here. Further, the MCQ Questions for Class 12 Electrostatic Potential and Capacitance with Answers provided here can be used by students to understand the concepts discussed in the chapter in detail. Scoring good marks in class 12 board exams is extremely important for every student.

These Important Questions with Answers are created by individual subject experts according to the latest CBSE guidelines. These MCQ Questions can be used by students to understand the concepts discussed in the chapter in detail. So, they can make a quick revision of all the important topics and MCQ Questions with Answers confident the board exams.

Practice MCQ Question for Class 12 Physics chapter-wise 

1. If a conductor has a potential V ≠ 0 and there are no charges anywhere else outside, then

(a) there must be charges on the surface or in¬side itself
(b) there cannot be any charge in the body of the conductor
(c) there must be charges only on the surface
(d) both (a) and (b) are correct

2. A parallel plate air capacitor is charged to a potential difference of V volts. After disconnecting the charging battery the distance between the plates of the capacitor is increased using an insulating handle. As a result the potential difference between the plates

(a) increases
(b) decreases
(c) does not change
(d) becomes zero

3. Two identical capacitors are joined in parallel, charged to a potential V, separated and then connected in series, the positive plate of one is connected to the negative of the other. Which of the following is true?

(a) The charges on the free plated connected together are destroyed.
(b) The energy stored in ths system increases
(c) The potential difference between the free plates is 2V
(d) The potential difference remains constant

4. Two spherical conductors each of capacity C are charged to potential V and -V. These are then connected by means of a fine wire. The loss of energy is

(a) zero
(b) 1/2 CV²
(c) CV²
(d) 2 CV²

5. Two copper spheres of the same radius, one solid and the other hollow, are charged to the same potential. Which will have more charge?

(a) Solid sphere
(b) Hollow sphere
(c) Both will have an equal charge
(d) None of these

6. A bird sitting on a high power line:

(a) gets killed instantly
(b) gets a mild shock
(c) gets a fatal shock
(d) is not affected practically

7. Choose the SI unit of electric potential energy :

(a) Joule
(b) Coulomb
(c) Netwon per coulomb
(d) Erg

8. When a dielectric slab is introduced between the plates of a parallel plate capacitor which remains connected to a battery then charge on the plates relative to earlier charge is :

(a) more
(b) less
(c) less or may be more
(d) same

9. The electric potential of earth is taken as:

(a) zero
(b) infinity
(c) unity
(d) None of these

10. A positively charged particle is released from rest in an uniform electric field. The electric potential energy of the charge

(a) remains a constant because the electric field is uniform
(b) increases because the charge moves along the electric field
(c) decreases because the charge moves along the electric field
(d) decreases because the charge moves opposite to the electric field 

11. Equipotentials at a great distance from a collection of charges whose total sum is not zero are approximately

(a) spheres
(b) planes
(c) paraboloids
(d) ellipsoids

12. The electric potential inside a conducting sphere

(a) increases from centre to surface
(b) decreases from centre to surface
(c) remains constant from centre to surface
(d) is zero at every point inside

13. It becomes possible to define potential at a point in an electric field because electric field

(a) is a conservative field
(b) is a non-conservative field
(c) is a vector field
(d) obeys principle of superposition

14. There are two metallic spheres of same radii but one is solid and the other is hollow, then

(a) solid sphere can be given more charge
(b) hollow sphere can be given more charge
(c) they can be charged equally (maximum)
(d) None of the above

15. The positive terminal of 12 V battery is connected to the ground. Then the negative terminal will be at

(a) – 6 V
(b) + 12 V
(c) zero
(d) – 12 V

16. A hollow metal sphere of radius 5 cm is charged such that the potential on its surface is 10 V. The potential at a distance of 2 cm from the centre of the sphere is

(a) zero
(b) 10 V
(c) 4 V
(d) 10/3 V

17. Energy is stored in a capacitor in the form of

(a) electrostatic energy
(b) magnetic energy
(c) light energy
(d) heat energy

18. In a charged capacitor, the energy is stored in

(a) the negative charges
(b) the positive charges
(c) the field between the plates
(d) both (a) and (b)

19. Capacitors are used in electrical circuits where appliances need more

(a) voltage
(b) current
(c) resistance
(d) power

20. Assertion : Electric field is discontinuous across the surface of a spherical charged shell.

Reason : Electric potential is continuous across the surface of a spherical charged shell

(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct

21. A table tennis ball that has been covered with conducting paint is suspended by a silk thread so that it hangs between two plates, out of which one is earthed and other is connected to a high voltage generator. This ball

(a) Is attracted towards high voltage plate and stays there
(b) Hangs without moving
(c) Swing backward and forward hitting each plate in turn
(d) Is attracted to the earthed plate and stays there

22. If a unit positive charge is taken from one point to another over an equipotential surface, then-

(a) Work is done on the charge
(b) Work is done by the charge
(c) Work done is constant
(d) No work is done

23. When one electron is taken towards the other electron, then the electric potential energy of the system -

(a) Decreases
(b) Increases
(c) Remains unchanged
(d) Becomes zero

24. Equipotential surfaces associated with an electric field which is increasing in magnitude along the x-direction are

(a) Planes parallel to yz-plane
(b) Planes parallel to xy-plane
(c) Planes parallel to xz-plane
(d) Coaxial cylinders of increasing radii around the x-axis

25. If the dielectric constant and dielectric strength be denoted by k and x respectively, then a material suitable for use as a dielectric in a capacitor must have

(a) High k and high x
(b) High k and low x
(c) Low k and low x
(d) Low k and high x

Answer :

1. Answer : (c) there must be charges only on the surface

Explanation: If a conductor has a non zero potential and there are no charges anywhere else outside, then there must be charges on the surface of the conductor or inside the conductor. There cannot be any charge in the body of the conductor.

2. Answer : (a) increases

Explanation: When battery is disconnected and the distance between the plates of the capacitor is increased then capacitance increases and charge remains constant. ∴ Potential difference increases.

3. Answer : (c) The potential difference between the free plates is 2V

Explanation: The charges on the inner plates are bound. Capacitance is halved. So, potential difference is doubled but energy stored remains unchanged.

4. Answer : (c) CV²

Explanation: Here, loss of energy

\(=\frac{C_1C_2(V_1+V_2)^2}{2(C_1+C_2)}\)

\(=\frac{CC(V+V)^2}{2(C+C)}\)

5. Answer : (c) Both will have an equal charge

Explanation: We know that the charges reside on the surface of a conductor. Here the two copper spheres are two conductors. So the charge uniformly distributed on the surface on the both sphere. We know that potential at the surface is \(V=\frac{kq}{R}\) . As the both spheres have same radius and charged to same potential so they will have equal charge.

6. Answer : (d) is not affected practically

Explanation: A bird is not affected practically because both of its legs are at same potential thus, current cannot flow through its body.

7. Answer : (a) Joule

Explanation: The SI unit of electric potential energy is joule (named after the English physicist James Prescott Joule). In the CGS system the erg is the unit of energy, being equal to 10⁻⁷ Joules.

8. Answer : (a) more

Explanation: When dielectric is introduced, the capacitance will increase and as the battery remains connected, so the voltage will remain constant. Hence according to Q = CV the charge will increase.

9. Answer : (a) zero

Explanation: Electric potential of earth is taken as zero, because the capacitance of earth is taken infinite.

10. Answer : (c) decreases because the charge moves along the electric field

Explanation: In a uniform electric field, when a positively charged particle is released from rest, it moves along the electric field, that is from higher potential to lower potential. Therefore, electric potential energy of charge decreases.

11. Answer : (a) spheres

Explanation: For a collection of charges, whose total sum is not zero, equipotentials at large distances must be spheres only.

12. Answer : (c) remains constant from centre to surface

Explanation: Electric potential inside a conductor is constant and it is equal to that on the surface of conductor.

13. Answer : (a) is a conservative field

Explanation: It becomes possible to define potential at a point in an electric field because electric field is a conservative field.

14. Answer : (c) they can be charged equally (maximum)

Explanation: Because in case of metallic sphere either solid or hollow, the charge will reside on the surface of the sphere. Since both spheres have same surface area, so they can hold equal maximum charge.

15. Answer : (d) – 12 V

Explanation: When negative terminal of battery is grounded, positive terminal of battery is at +12V . When positive terminal is grounded, the negative terminal will be at −12V.

16. Answer : (b) 10 V

Explanation: Hollow metal sphere = spherical shell

Electric field inside shell = 0

B is Potential in constant inside thin shell

potential at surface = potential at centre 

=10 V.

17. Answer : (a) electrostatic energy

Explanation: Energy stored in a capacitor is in the form of electrical potential energy, and it is thus related to the charge Q and voltage V on the capacitor.

18. Answer : (c) the field between the plates

Explanation: Electrostatic energy of a condenser lies in the field in between the plates of the condenser.

19. Answer : (b) current

Explanation: Capacitors are commonly used in electronic devices to maintain their power supply and some appliances need rapid current so they can start. So the capacitors are used in electrical circuits where appliances need current. 

20. Answer : (b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

Explanation: Electric field is zero inside the spherical charged shell and it is \(\frac{\sigma}{\varepsilon_0}\pi\) outside. So it is discontinuous across the surface. Electric potential is continuous across the surface.

21. Answer : (c) Swing backward and forward hitting each plate in turn

Explanation: When the other piate is connected to the high voltage generator, the negative charge induced on the ball cause attraction. When it strikes the +ve plate charge distribution again takes piace.This causes repulsion. Hence, the ball swings backward and forward hitting each plate in turn.

22. Answer : (d) No work is done

Explanation: Since the potential at each point of an equipotential surface is the same, the potential does not change while we move a unit positive charge from one point to another. Therefore work done in the process is zero.

23. Answer : (b) Increases

Explanation: when an electron is brought near another electron, the work has to be done against the repulsive force since like charges repel each other. This work done is stored in the form of electrostatic potential energy and hence the electric potential energy of the system increases.

24. Answer : (a) Planes parallel to yz-plane

Explanation: Any surface which has same electrostatic potential at every point is called an equipotential surface. Electric field is always perpendicular to an equipotential surface. Therefore x-direction is perpendicular only to yz plane.

25. Answer : (a) High k and high x

Explanation: High K means good insulating propetry and high x means able to withstand electric field gradient to a higher value.

Click here to practice  MCQ Question for Electrostatic Potential and Capacitance Class 12

Students are encouraged to more practice Class 10 Science MCQ Questions Magnetic Effects of Electric Current with Answers is accessible here. Students can tackle these MCQ Questions Magnetic Effects of Electric Current with Answers and evaluate their exam preparation level.

Practice Class 10 Science MCQ Questions of Magnetic effects of electric current

1. Who has stated the Right hand Thumb Rule?

(a) Orsted
(b) Fleming
(c) Einstein
(d) Maxwell

2. Magnetic effect of current was discovered by

(a) Oersted
(b) Faraday
(c) Bohr
(d) Ampere

3. Inside the magnet, the field lines moves

(a) from north to south
(b) from south to north
(c) away from south pole
(d) away from north pole

4. Which of the following statement is not correct about the magnetic field?

(a) Magnetic field lines form a continuous closed curve.
(b) Magnetic field line do not interest each other.
(c) Direction of tangent at any point on the magnetic field line curve gives the direction of magnetic field at that point.
(d) Outside the magnet, magnetic field lines go from South to North pole of the magnet.

5. The nature of magnetic field line passing through the centre of current carrying circular loop is

(a) circular
(b) ellipse
(c) parabolic
(d) straight line

6. What should be the core of an electromagnet?

(a) soft iron
(b) hard iron
(c) rusted iron
(d) none of above

7. The strength of magnetic field inside a long current carrying straight solenoid is

(a) more at the ends than at the centre
(b) minimum in the middle
(c) same at all points
(d) found to increase from one end to the other

8. The most important safety method used for protecting home appliances from short circuiting or overloading is by

(a) earthing
(b) use of fuse
(c) use of stabilizers
(d) use of electric meter.

9. Select the incorrect statement

(а) Magnetic field lines are closed curves
(b) No two field lines can cross each other
(c) Field lines can cross each other
(d) The relative strength of the magnetic field is shown by degree of closness of the field lines.

10. Magnetic field lines around a straight conductor forms a pattern of

(a) concentric circles
(b) concentric ellipse
(c) straight line
(d) square shape.

11. Electric motor is a device which converts

(a) mechanical energy to electrical energy
(b) electrical energy to mechanical energy
(c) chemical energy to mechanical energy
(d) mechanical energy to light energy.

12. The direction of induced current is given by

(a) Fleming’s right hand rule
(b) Fleming’s left hand rule
(c) Right hand thumb rule
(d) Left hand thumb rule.

13. Unit of intensity of magnetic field is:

(a) Tesla
(b) Ohm
(c) Ampere
(d) Volt-ampere

14. A current carrying conductor is placed in between the poles of the stable magnetic field. The direction of force acting on the conductor is given by the law:

(a) Maxwell’s Cark-screw rule
(b) Fleming’s Right hand rule
(c) Fleming’s left hand rule
(d) Ohm’s law.

15. In electric motor, to make the coil rotating continuously in the same direction, current is reversed in the coil after every half rotation by a device called

(a) carbon brush
(b) commutator
(c) slip ring
(d) armature

Answer:

(b) commutator

Explanation:

A device that reverses the direction of current in the arms of armature through a circuit is called commutation.

16. Earth wire carries

(a) current
(b) voltage
(c) no current
(d) heat

17. The insulation colour of earth wire is

(a) blue
(b) red
(c) green
(d) white.

18. The magnitude of induced e.m.f. is:

(a) proportional to the rate of change of field lines
(b) proportional to earth’s magnetic field
(c) depend on material of coil
(d) inversely proportional to the rate of change of speed of magnet.

19. Lenz’s law is based on which conservation law:

(a) charge
(b) mass
(c) momentum
(d) energy

20. Dynamo converts:

(a) chemical energy into electric energy
(b) sound energy into magnetic energy
(c) mechanical energy into electric energy
(d) mechanical energy into light energy.

Answer key

1. (d) Maxwell

2. (a) Oersted

Explanation: Oersted showed that electricity and magnetism were related phenomena.

3. (b) from south to north

Explanation: Magnetic field inside the magnet moves from south to north pole.

4. (d) Outside the magnet, magnetic field lines go from South to North pole of the magnet.

Explanation: Outside the magnet, magnetic field line emerges from North-pole and moves towards south-pole.

5. (d) straight line

Explanation: Magnetic field line at the centre of current carrying loop appears as a straight line.

6. (a) soft iron

7. (c) same at all points

8. (b) use of fuse

9. (c) Field lines can cross each other

10. (a) concentric circles

11. (b) electrical energy to mechanical energy

12. (a) Fleming’s right hand rule

13. (a) Tesla

14. (c) Fleming’s left hand rule

15. (b) commutator

Explanation: A device that reverses the direction of current in the arms of armature through a circuit is called commutation.

16. (c) no current

17. (c) green

18. (a) proportional to the rate of change of field lines

19. (d) energy

20. (c) mechanical energy into electric energy

Click here to practice more MCQ Questions from Chapter Magnetic effects of electric current Class 10 Science

CBSE Class 10 Science The Human Eye and The Colourful World MCQ Questions with answers accessible here. Multiple Choice Questions for a significant piece of exams for Grade 10 Science and whenever practiced appropriately can assist you with getting better marks.

Practice Class 10 Science MCQ Questions of The Human Eye and the Colourful World

Refer to more Chapter-wise MCQ Questions of The Human Eye and The Colourful World with Answers. MCQ Questions will help students to comprehend their Knowledge level.

1. The image formed by retina of human eye is

(a) Virtual and erect
(b) Real and inverted
(c) Virtual and inverted
(d) Real and erect

2. The light sensitive cell present on retina and is sensitive to the intensity of light is:

(a) Cones
(b) Rods
(c) Both rods and cones
(d) None of these

3. The part of the eyes refracts light entering the eye from external objects?

(a) Lens
(b) Cornea
(c) Iris
(d) Pupil

4. The amount of light entering the human eye is controlled by

(a) Ciliary muscles
(b) Pupil
(c) Cornea
(d) Iris

5. At noon the sun appears white as

(a) light is least scattered.
(b) all the colours of the white light are scattered away.
(c) blue colour is scattered the most.
(d) red colour is scattered the most.

6. Which of the following phenomena of light are involved in the formation of a rainbow?

(a) Reflection, refraction and dispersion
(b) Refraction, dispersion and total internal reflection
(c) Refraction, dispersion and internal reflection
(d) Dispersion, scattering and total internal reflection

7. Twinkling of stars is due to atmospheric

(a) dispersion of light by water droplets
(b) refraction of light by different layers of varying refractive indices
(c) scattering of light by dust particles
(d) internal reflection of light by clouds

8. The clear sky appears blue because

(а) blue light gets absorbed in the atmosphere.
(b) ultraviolet radiations are absorbed in the atmosphere.
(c) violet and blue lights get scattered more than lights of all other colours by the atmosphere.
(d) light of all other colours is scattered more than the violet and blue colour lights by the atmosphere.

9. The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light

(a) is scattered the most by smoke or fog.
(b) is scattered the least by smoke or fog.
(c) is absorbed the most by smoke or fog.
(d) moves fastest in air.

10. The focal length of the eye lens increases when eye muscles

(a) are relaxed and lens becomes thinner
(b) contract and lens becomes thicker
(c) are relaxed and lens becomes thicker
(d) contract and lens becomes thinner

11. Human eye is formed image on:

(a) cornea
(b) iris
(c) pupil
(d) retina

12. Far point of a man suffering from short-sightedness is:

(a) at 25 cm
(b) at less than 25 cm
(c) at infinity
(d) at less than infinity.

13. Image formed in normal eye of human is:

(a) on retina
(b) beyond retina
(c) behind retina
(d) at infinity.

14. Minimum distance of clear vision is:

(a) 25 cm
(b) 2.5 cm
(c) 25 cm
(d) 2.5 cm

15. Eye lens is:

(a) converging
(b) diverging
(c) convex and concave
(d) none of these

16. The black opening between the aqueous humour and the lens is called

(a) retina
(b) iris
(c) cornea
(d) pupil

17. Myopia and hypermetropia can be corrected by

(a) Concave and plano-convex lens
(b) Concave and convex lens
(c) Convex and concave lens
(d) Plano-concave lens for both defects.

18. Bi-focal lens are required to correct

(a) astigmatism
(b) coma
(c) myopia
(d) presbyopia

19. Refraction of light by the earth’s atmosphere due to variation in air density is called

(a) atmospheric reflection
(b) atmospheric dispersion
(c) atmospheric scattering
(d) atmospheric refraction

20. One cannot see through the fog, because

(a) refractive index of the fog is very high
(b) light suffers total reflection at droplets
(c) fog absorbs light
(d) light is scattered by the droplets

Answer Key

1. (b) Real and inverted

2. (b) Rods

3. (b) Cornea

4. (b) Pupil

5. (a) light is least scattered.

6. (c) Refraction, dispersion and internal reflection

7. (b) refraction of light by different layers of varying refractive indices

8. (c) violet and blue lights get scattered more than lights of all other colours by the atmosphere.

9. (b) is scattered the least by smoke or fog.

10. (a) are relaxed and lens becomes thinner

11. (d) retina

12. (b) at less than 25 cm

13. (a) on retina

14. (c) 25 cm

15. (a) converging

16. (d) pupil

17. (b) Concave and convex lens

18. (d) presbyopia

Explanation: Bifocal lens is required to correct the presbyopia. Upper point of bifocal lens consists of concave lens used for distant vision while lower point consists of convex lens facilitate near vision.

19. (d) atmospheric refraction

Explanation: This phenomenon is called atmospheric refraction.

20. (d) light is scattered by the droplets

Explanation: Objects are not visible through the fog because droplets scatter the light rays.

Click here to practice more MCQ Questions from Chapter The Human Eye and the Colourful World Class 10 Science

Reproduction with seeds is called sexual reproduction

MCQ Questions for class 10 science Metals and Non-metals will help you with getting prepare with the different strategies for these chapters and besides what kind of Questions can be asked in the exam. Answer to all Questions is moreover given point-by-point explanation which makes clear the idea.

Practice Class 10 Science MCQ Questions of Metals and Non-Metals

1. Galvanisation is a method of protecting iron from grudging by coating with a thin layer of

(a) Galium
(b) Aluminium
(c) Zinc
(d) Silver

Answer:

(c) Zinc

2. The ability of metals to be drawn into thin wire is known as

(a) Ductility
(b) Malleability
(c)Sonorousity
(d) Conductivity

Answer:

(b) Malleability

3. Copper objects lose their shine and form green coating of

(a) Copper oxide
(b) Copper hydroxide and Copper oxide
(c) Basic Copper carbonate
(d) Copper carbonate

Answer:

(c) Basic Copper carbonate

4. Chemically rust is

(a) Hydrated ferrous oxide
(b) Hydrated ferric oxide
(c) only ferric oxide
(d) none of these

Answer: 

(b) Hydrated ferric oxide

5. Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?

(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point

(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (i) and (iv)

Answer:

(d) (i) and (iv)

6. Which one of the following four metals would be displaced from the solution of its salts by other three metals?

(a) Mg
(b) Ag
(c) Zn
(d) Cu

Answer:

(b) Ag

7. Which of the given properties is generally not shown by metals?

(a) Electrical conduction
(b) Sonorous in nature
(c) Dullness
(d) Ductility

Answer:

(c) Dullness

8. Which of the given can undergo a chemical reaction?

(a) \(MgSO_4 + Fe\)
(b) \(ZnSO_4 + Fe\)
(c) \(MgSO_4 + Pb\)
(d) \(CuSO_4 + Fe\)

Answer:

(d) \(CuSO_4 + Fe\)

9. Metals are extracted from:

(a) compounds
(b) minerals
(c) ores
(d) both minerals and ores.

Answer:

(c) ores

10. Calcination is :

(a) heating the ore in a limited supply of air
(b) heating the ore in excess of air
(c) cooling the ore
(d) none of these.

Answer:

(a) heating the ore in a limited supply of air

11. Setting of Plaster of Paris takes place due to

(a) Solder
(b) Bronze
(c) Brass
(d) Bell metal

Answer:

(a) Solder

12. Heating pyrites to remove sulphur is called

(a) Smelting
(b) Calcination
(c) Liquation
(d) Roasting

Answer:

(d) Roasting

13. The second most abundant metal in the earth’s crust is

(a) oxygen
(b) silicon
(c) aluminium
(d) iron

Answer:

(d) iron

14. A student placed an iron nail in copper sulphate solution. He observed the reddish brown coating on the iron nail which is

(a) soft and dull
(b) hard and flading
(c) smooth and shining
(d) rough and granular

Answer:

(d) rough and granular

15. An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept in open. It reacts vigorously with water. Identify the element from the following:

(a) Mg
(b) Na
(c) P
(d) Ca

Answer:

(b) Na

16. Alloys are homogeneous mixtures of a metal with a metal or non-metal. Which among the following alloys contain non-metal as one of its constituents?

(a) Brass
(b) Bronze
(c) Amalgam
(d) Steel

Answer:

(d) Steel

17. During smelting, an additional substance is added which combines with impurities to form a fusible product. It is known as

(a) Slag
(b) Mud
(c) Gangue
(d) Flux

Answer:

(d) Flux

18. In extraction of copper, the flux used is

(a) \(CaO\)
(b) \(SiO_2\)
(c) \(FeO\)
(d) \(FeSiO_3\)

Answer:

(b) \(SiO_2\)

19. Metal always found in free state is:

(a) Gold
(b) Silver
(c) Copper
(d) Sodium

Answer:

(a) Gold

20. Reaction between X and Y, forms compound Z. X loses electron and Y gains electron. Which of the following properties is not shown by Z?

(a) Has high melting point
(b) Has low melting point
(c) Conducts electricity in molten state
(d) Occurs as solid

Answer:

(b) Has low melting point

Click here to practice more MCQ Questions from Chapter Metals and Non-Metals Class 10 Science

Reproduction in plants without seeds is called asexual reproduction.

1. Reproduction of plants from all such parts other than the flower is asexual reproduction. 

2. It is a great thing in nature because reproduction in plants is not confined only to sexual reproduction. 

3. By way of such processes, we could get good vegetation.

For passage of electricity through a material or substance charged particles are required. In metals charged particles are electrons whereas in solutions ions are charged particles which carry electrical energy. Solutions of acids, bases and salts undergo ionisation and produce ions. So they are good conductors of electricity

In some plants sexual reproduction occurs through some vegetative parts like stem, roots and leaf.

 Practice with significant Class 7 Science MCQ Questions of Reproduction in Plants with Answer to learn the better way whole section of NCERT book. We have aggregated the MCQ Questions for Class 7 Science Reproduction in Plants with Answers covering the whole prospectus. Practice MCQ Questions for Class 7 Science with Answers consistently and score well in exams. It help to score more in assessment. Every one of the Questions is replied to with reasonable clarification. 

Students can Solve this Reproduction in Plants Class 7 MCQ Questions with Answers and evaluate their preparation level. MCQ Questions for Class 7 Science with Answers are prepared according to the Latest Exam Pattern. These MCQ Questions on Reproduction in Plants Class 7 with answers for a speedy revision of the Chapter in this way assisting you with upgrading subject information. You can likewise check your answers from our gave Reproduction in Plants with Answer class 7 MCQ Questions with Answers.

Practice MCQ Questions for Class 7 Science

1. Vegetative propagation in potato takes place by

(a) leaves
(b) stem
(c) root
(d) seed

2. In which of the following plants buds are present on the margins of leaves?

(a) Bryophyllum
(b) Touch me not
(c) Chandan
(d) Coriander

3. In yeasts reproduction occurs by

(a) fragmentation
(b) binary fission
(c) budding
(d) spore formation

4. Lila observed that a pond with clear water was covered up with a green algae within a week. By which method of reproduction did the algae spread so rapidly ?

(a) Budding
(b) Sexual reproduction
(c) Fragmentation
(d) Pollination

5. Seeds of drumstick and maple are carried to long distances by wind because they possess

(a) winged seeds
(b) large and hairy seeds
(c) long and ridged fruits
(d) spiny seeds

6. The ‘eye of the potato plant is what

(a) the root is to any plant
(b) the bud is to a flower
(c) the bud is to Bryophyllum leaf
(d) the anther is to stamen

7. The ovaries of different flowers may contain

(a) only one ovule
(b) many ovules
(c) one to many ovules
(d) only two ovules

8. Pollination refers to the:

(a) transfer of pollen from anther to ovary
(b) transfer of male gametes from anther to stigma
(c) transfer of pollen from anther to stigma
(d) transfer of pollen from anther to ovule

9. The production of new individuals from their parents is known as ______ 

(a) Reproduction
(b) Production
(c) Vegetative propagation
(d) Sprouting

10. Male reproductive part of a plant is 

(a) Pores
(b) Pistil
(c) Stamen 
(d) Fusion

11.  Reproduction through spore formation takes place in 

(a) Fern
(b) Algae 
(c) Fungi
(d) Yeast

12. The flowers which contain either only the pistil or only the stamens are called 

(a) Unisexual flowers 
(b) Bisexual flowers
(c) Asexual flowers 
(d) None of the above

13. The cell which results after fusion of the gametes is called 

(a) Spore 
(b) Embryo 
(c) Zygote 
(d) Pistil

14. The transfer of pollen from the anther to the stigma of a flower is called:

(a) fragmentation
(b) fertilisation
(c) pollination
(d) reproduction 

15. Reproduction is essential for living organism in order to

(a) Keep individual organ alive
(b) Maintain growth
(c) Fulfill their energy requirement
(d) continue the species forever 

16. The zygote develops into

(a) a seed
(b) an ovule
(c) a fruit
(d) an embryo

17. Rose and lemon are grown from:

(a) tubers
(b) bulbs
(c) stem cuttings
(d) leaf buds

18.The seeds dispersed by birds and animals are:

(a) less smell
(b) very smelly
(c) with smell and nectar
(d) none of these 

19. What is the function of flower in plants:

(a) reproduction
(b) transportation
(c) transpiration
(d) respiration 

20. Mature ovule forms

(a) Buds
(b) Endosperm
(c) Fruit
(d) Seed

Answer:

1.Answer: (b) stem

Explanation: Potato is the underground modification of stem. It is called as stem tuber. Potato reproduces asexually by the process of vegetative propagation.

2. Answer: (a) Bryophyllum

Explanation:  In bryophyllum Plant buds are present on the margin of leaves.

3. Answer: (c) budding

Explanation:  Binary fission is the process of parent cell splitting into two equal daughter cells. It takes place in prokaryotes (bacteria and archaea) only.
Budding is the process similar to binary fission the daughter cells grow from the parent's body and are detached to form separate individuals in time. The offsprings are always smaller than the parents. This method is observed in yeast along with lower multicellular life forms like hydra.Spore formation or sporogenesis takes place in many multicellular organisms via mitosis and meiosis cell cycles. Spores formed develop into haploid (meiosis) or diploid (mitosis) individuals after dispersion. This method is even found in conidium fungi (not yeast).

4. Answer: (c) Fragmentation

Explanation:  In Spirogyra, asexual reproduction takes place by fragmentation.

5. Answer: (a) winged seeds 

Explanation:  Seeds of maple and drumstick have wings. The winged seeds help them to travel long distances by wind. Seeds of drumstick and maple have wings which help them to be easily carried away by wind.

6. Answer: (c) the bud is to Bryophyllum leaf

Explanation:  Each tuber or potato has several buds. These are the small sprouts we call potato “eyes." It's from these buds that new potato plants can grow. So even though a potato's eyes can't help it see underground, they can help grow more potatoes.

7. Answer: (c) the bud is to Bryophyllum leaf

Explanation:  In an ovary, the numbers of ovules are not equal for every flower. There can be a single or many ovules present in flower.

8. Answer: (c) transfer of pollen from anther to stigma

Explanation:  The transfer of pollen grains from the anther to the stigma is called pollination.

9. Answer: (a) Reproduction

Explanation:  The production of new individuals from their parents is known as Reproduction.

10. Answer: (c) Stamen 

Explanation: stamen consists of an anther (which produces pollen, the male reproductive cell) and a filament.

11. Answer: (a) Fern

Explanation:  Ferns and horsetails have two free-living generations: a diploid sporophyte generation (spore-producing plant) and. a haploid gametophyte generation (gamete-producing plant).

12. Answer: (a) Unisexual flowers 

Explanation:  Stamen (filament and an anther) is the male part and the pistil (stigma, style, and the ovary) is the female part of a flower. Note: Lily, rose, sunflower, mango, etc. are bisexual flowers while papaya, snake guard, bitter guard, cucumber, and watermelon flowers are unisexual flowers.

13. Answer: (c) Zygote

Explanation:  During the process of fertilization, a series of reactions triggers the fusion of gametes to produce a diploid cell called a zygote.

14. Answer: (c) pollination

Explanation: The transfer of pollen grain from the anther to the stigma of a pistil is called pollination.

15. Answer: (d) continue the species forever 

Explanation:  Reproduction is essential for all organisms for continuation of the species generation after generation and to maintain a steady species population, so that, it does not become extinct

16. Answer: (d) an embryo

Explanation:  First, the zygote becomes a solid ball of cells. Then it becomes a hollow ball of cells called a blastocyst. Inside the uterus, the blastocyst implants in the wall of the uterus, where it develops into an embryo attached to a placenta and surrounded by fluid-filled membranes.

17. Answer: (c) stem cuttings

Explanation:  Rose and lemon are grown from stem cutting.

18.Answer: (c) with smell and nectar

Explanation: Dates, rambutan, sea grapes, sea holly, tamarind, raspberry, sunflower, tomatoes are a few examples of plants whose seeds are dispersed by animals and birds.

19. Answer: (a) reproduction

Explanation: The function of a flower is to carry out sexual reproduction in plants through the formation of male and female gametes.

20. Answer: (d) Seed

Explanation: After the process of fertilization, the zygote, in time, differentiates to form an embryo inside the ovule. The ovary matures to turn into the fruit which can either be fleshy or dry, in which the seeds are embedded.

Click here for Practice MCQ Questions for Reproduction in Plants Class 7

Students can refer to Class 10 Science MCQ Questions of Carbon and Its Compounds with Answer and evaluate their preparation level. Check below the MCQ Questions with Answers to increase your speed in exams and Clear your concept.

Practice Class 10 Science MCQ Questions of Carbon and its Compounds

1. The substnace not responsible for the hardness of water is

(a) Sodium nitrate
(b) calcium hydrogen carbonate
(c) calcium carbonate
(d) magnesium carbonate

2. Which amongst the following will conduct electricity?

(a) \(C_6H_{12}O_6\)
(b) \(KCl(s)\)
(c) \(C_2H_5OH\)
(d) \(NaCl (aq)\)

3. Artificial flavour for orange is obtained from

(a) amyl acetate
(b) isoamyl valerate
(c) methyl butyrate
(d) octyl acetate

4. Covalent compounds

(a) have high melting and boiling point
(b) are mostly soluble in water
(c) are formed between atoms of metals and non-metals
(d) are formed by the sharing of electrons in the bonding atoms.

5. Which is denatured spirit?

(a) ethanol only
(b) ethanol and methanol (50%)
(c) ethanol and methanol (5%)
(d) methanol only

6. Soaps are formed by saponification of

(a) alcohols
(b) glycosides
(c) simple esters
(d) carboxylic acids

7. Assertion: Soaps are 100% biodegradable but do not work well with hard water.

Reason: Some detergents are not bio-degradable but work well with hard water.

(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
(e) Both A and R are false.

8. Ethanol reacts with Na metal to form

(a) \(CH_3ONa + H_2\)
(b) \(C_2H_5ONa + H_2\)
(c) \(CH_3COONa + H_2\)
(d) \(CH_3COOH + H_2O\)

9. The isomeric pair is

(a) Ethane and propane
(b) Propane and butane
(c) Ethane and ethane
(d) Butane and 2-methylpropane

10. The by product of soap is

(a) Isoprene
(b) Glycerol
(c) Butene
(d) Ethylene glycol

11. A functional group mainly determines the

(a) Physical properties
(b) Chemical properties
(c) Both
(d) None of these

12. 100% pure ethanol is called

(a) Rectified spirit
(b) Absolute alcohol
(c) Denatured alcohol
(d) Power alcohol

13. Graphite is used as a lubricant in machines because

(a) it is a good conductor of electricity.
(b) it has a high melting point and slippery layers.
(c) its density ranges from 1.9 to 2.3 \(g/cm^3\).
(d) it is strong and soft.

14. The allotrope of carbon which is a good conductor of heat and electricity is

(a) diamond
(b) graphite
(c) charcoal
(d) none of these

15. Which of the following does not belong to the same homologous series?

(a) \(CH_4\)
(b) \(C_2H_6\)
(c) \(C_3H_8\)
(d) \(C_4H_8\)

16. Ethane, with the molecular formula \(C_2H_6\) has :

(a) 6 covalent bonds
(b) 7 covalent bonds
(c) 8 covalent bonds
(d) 9 covalent bonds.

17. Butanone is a four-carbon compound with the functional group:

(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol

18. The chemical formulae of propane is :

(a) \(CH_4\)
(b) \(C_3H_8\)
(c) \(C_4H_{10}\)
(d) \(C_2H_6\)

19. I.U.P.A.C. name of acetaldehyde is:

(a) Ethanol
(b) Ethanal
(c) Methanol
(d) Methanal

20. Solubility of alcohol in water is due to

(a) low density of alcohol
(b) volatile nature of alcohol
(c) ionisation
(d) hydrogen bonding

Answer Key

1. (a) Sodium nitrate
2. (d) \(NaCl (aq)\)
3. (d) octyl acetate
4. (d) are formed by the sharing of electrons in the bonding atoms.
5. (c) ethanol and methanol (5%)
6. (c) simple esters
7. (b) Both A and R are true but R is not the correct explanation of A.
8. (b) \(C_2H_5ONa + H_2\)
9. (d) Butane and 2-methylpropane
10. (b) Glycerol
11. (b) Chemical properties
12. (b) Absolute alcohol
13. (b) it has a high melting point and slippery layers.
14. (b) graphite
15. (d) \(C_4H_8\)
16. (b) 7 covalent bonds
17. (c) ketone
18. (b) \(C_3H_8\)
19. (b) Ethanal
20. (d) hydrogen bonding

Click here to practice more MCQ Questions from Chapter Carbon and its Compounds Class 10 Science

Acids Bases and Salts:

In this article, the notes of acids bases and salts for class 10 is provided. It will make you easy to revise throughout quickly for the purpose of your exams.

Types of Indicator:

The following types of indicator are used to test whether one is acid or base. Each has its own action on acid and base. As blue litmus is turned to red when subjected to acids and on the other hand when red litmus is subjected to base it turns to blue. Similarly, all the indicators have the same role.

Acid:

A compound, which on dissolving in water gives hydronium ions (H₃O⁺) as the only positive ions are acid.

Chemical properties of acids:

• The word ‘acid’ is derived from a Latin word ‘acidus’, which means “sour”.
• Acidic nature of a substance is due to the formation of H+(aq) ions in solution.

1. Reaction of acid with metal:

Acid + Metal → Salt + Hydrogen gas

When an acid reacts with a metal, hydrogen gas is evolved and a corresponding salt is formed.
Example:
2NaOH + Zn → K₂ZnO₃ + H₂

2. Reaction of acid with metal carbonate and metal hydrogen carbonates:

Acid + Metal carbonate / Metal hydrogen Carbonate → Salt + CO₂ + H₂O

When an acid reacts with a metal carbonate (MCO₃) or metal hydrogen carbonate (MHCO₃), it gives the corresponding salt, carbon dioxide(CO₂) gas and water.
Example:
Na₂CO₃(S) + 2HCl(aq) → 2NaCl(aq) + H₂O(l) + CO₂(g)
NaHCO₃ (s) + HCl(aq) → NaCl(aq) + H₂O(l) + CO₂ (g)

3. Reaction of acid with base:

Acid + Base→ Salt + Water

Acid and base together react to produce salt and water. This reaction is called neutralization reaction.
Example: KOH(aq) + HCl(aq) → KCl(aq) + H₂O(l)

4. Reaction of Metallic Oxides with Acids:

Metal oxide + Acid → Salt + Water

Acids react with metal oxides to produce salt and water.
Example: CuO + HCl → CuCl₂ + H₂O

5. Conduction of electricity:

Acidic solutions in water conduct electricity because they produce hydronium ions. Hydrogen ions cannot exist alone, but they exist after combining with water molecules. Thus hydrogen ions must always be shown as H⁺(aq) or hydronium ion (H₃O⁺). i.e. H⁺ + H₂O → H₃O⁺.

6.Strength of acid:

We can test the strength of an acid by using a scale called the pH scale which gives the measure of hydrogen ion concentration in a solution.
pH value of acids is always less than 7.

Base:

A compound, which on dissolving in water gives hydroxide ions (OH^-) as the only negative ions is base or simply we can say that a base is ‘a compound which reacts with an acid to give salt and water only.

• Bases are bitter to taste. They are soapy and slippery to touch.
• The presence of basic property in bases is determined by the concentration of OH^- ion in water.

1. Base in water:

Bases generate hydroxide (OH^–) ions in water. Water soluble bases are called alkalis.
Example: Mg(OH)₂(s)  + H₂O → Mg⁺²(aq)+ OH (aq) + 2OH (aq)

2. Reaction of base with metal:

When base is reacted with some metals it forms hydrogen gas. However, these reactions are not possible with all the metals.
Example: 2NaOH + Zn → Na₂ZnO₂ + H₂

3. Reaction of a Non-metallic Oxide with Base:

Non-metallic oxides react with bases to form salt and water.
Example: CO₂(g) + Ca(OH)₂(aq) → CaCO₃(S) +  H₂O(l)
From this reaction, it is clear that Non-metallic oxides are acidic in nature.

4. Conduction of electricity:

Bases in water also conduct electricity as the acids do. As bases also dissociate into hydroxide ions in water thus conducts electricity. The process of dissolving a base in water is a highly exothermic one.

pH Scale:

pH Scale is a scale for measuring hydrogen ion concentration in a solution.

• The p in pH stands for ‘potenz’ in German, meaning ‘power’.
• The pH scale is marked with numbers 0 to 14, we should think pH simply as a number which indicates the acidic or basic nature of a solution.
• The pH varies from 0 (very acidic) to 7(neutral) and 14 (very alkaline).
• Higher will be the hydronium ion concentration, lower will be its pH value.

Importance of pH in everyday life:

1. Plants and animals are pH sensitive. If we talk of human body it works within the pH range of 7.0 to 7.8. Acid rain occurs when pH is less than 5.6 which affects the aquatic life.
2. For better growth of plants, the soil should have a specific pH range.
3. pH has a great role in our digestive system. Our stomach produces HCl acid which helps in the digestion of food without any harm.
4. When our mouth has pH less than 5.5 then our tooth decay starts. After eating, some food particles and sugar left in the mouth and with the help of it bacteria present in our mouth releases acid. Thus cause tooth decay.
5. Honeybee, ants and many other when bites us, causes pain and irritation. This is because they leave acid in our body. Some plants also cause the same. They use it for their self-defence.

Salts:

When an acid reacts with a base then it neutralizes to form salt and water. This reaction is called neutralization reaction.

• The H⁺ ion of acid and OH^- ions of base combine to form water(H₂O). The non-metallic ions of the acid and the metal ions of the base form the salt.
• Salts always stays in solution. Salts become solid when water is removed from it. Some salts are insoluble. They precipitate out when the acid and base are added together.
• The salt we eat is sodium chloride. It is formed by the combination of hydrochloric acid and sodium hydroxide solution.

Some more salts:

• Rock salt:
  Salt when present in its natural form as a crystalline mineral is rock salt or halite.
  When seas of bygone ages dried up, beds of rock salt were formed in the form of large brown crystals (brown due to impurities present in it).
• Common salt:
  Salt whose chemical composition is mainly NaCl is common salt.

Chlor-alkali process:

When we pass electricity through an aqueous solution of sodium chloride (called brine), it decomposes to form sodium hydroxide.
2NaCl(aq) + 2H₂O(l) → 2NaOH(aq) + Cl₂(g) + H₂(g)

• Bleaching powder:
  Bleaching powder (CaOCl₂) is produced by the action of chlorine (formed in chlor-alkali process) on dry slaked lime [Ca(OH)2].
  Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O

Uses of bleaching powder:

1. To bleach cotton and linen in the textile industry.
2. Many chemical industries use it as an oxidising agent.
3. To make drinking water free of germs by disinfecting it.

• Baking soda:
  When common salt is treated with Ammonia in the presence of water and carbon dioxide then baking soda (NaHCO₃) is formed.
  NaCl + H₂O + CO₂ + NH₃ → NH₄Cl + NaHCO₃

Uses of baking soda:

1. It is used for making baking powder (baking soda + mild edible acid).
2. Baking soda is also used in making antacids.
3. soda-acid fire extinguishers also use it as the main ingredient. 

• Washing soda:
  When we heat baking soda (NaHCO₃) it forms sodium carbonate (Na₂CO₃). When it combines with the excess of water than washing soda is obtained.
  2NaHCO₃ + Heat → Na₂CO₃ + H₂O + CO₂
  Na₂CO₃ + 10H₂O → Na₂CO₃ ∙ 10H₂O

Uses of washing soda:

1. Washing soda has main use in glass, paper and soap industries.
2. It is used in the manufacture of borax and many other sodium compounds.
3. We use it as a cleaning agent for domestic purposes.
4. Washing soda is used for removing permanent hardness of water.

• Plaster of Paris:
  When we heat gypsum at 373 K, it loses water molecules and becomes calcium sulphate hemihydrate (CaSO₄ . ½ H₂O). This is Plaster paris.

Uses and properties of plaster of paris:

1. Doctors mainly use it for supporting fractured bones in the right position.
2. It is a white powder but on mixing with water, it changes to hard solid mass i.e gypsum again.

Solving the Motion and Time Multiple Choice Questions of Class 7 Science MCQ can be of extreme help as you will be aware of all the concepts. MCQ Questions for Class 7 Science with Answers are prepared as per the Latest Exam Pattern. These MCQ Questions on Motion and Time Class 7 with answers for a quick revision of the Chapter thereby helping you to enhance subject knowledge. 

Students can solve these Motion and Time Class 7 MCQ Questions with Answers and assess their preparation level. Class 7 Science students should refer to the following multiple-choice questions with answers for Motion and Time in standard 7. These MCQ questions with answers for Grade 7 Science will come in exams and help you to score good marks.

Practice MCQ Questions for Class 7 Science

1. A bus travels 54 km in 90 minutes. The speed of the bus is

(a) 0.6 m/s
(b) 10 m/s
(c) 5.4 m/s
(d) 3.6 m/s

2. Nearly all the clocks make use of

(a) straight line motion
(b) periodic motion
(c) random motion
(d) circular periodic motion

3. A simple pendulum takes 32s to complete 20 oscillations, what is the time period of the pendulum? 

(a) 1.6 s
(b) 2.6 s
(c) 3.6 s
(d) 4.8 s

4.  Time period of a simple pendulum depends upon its

(a) weight of bob
(b) length
(c) both (a) and (b)
(d) None of these

5. Which of the following cannot be used for measurement of time?

(a) A leaking tap
(b) Simple pendulum
(c) Shadow of an object during the day
(d) Blinking of eyes

6. On which axis is dependent variable represented?

(a) x-axis
(b) y-axis
(c) On any axis
(d) Depends on the data

7. Boojho walks to his school which is at a distance of 3 km from his home in 30 minutes. On reaching he finds that the school is closed and comes back by a bicycle with his friend and reaches home in 20 minutes. His average speed in km/h is

(a) 8.3
(b) 7.2
(c) 5
(d) 3.6

8. The most well known periodic motion is that of

(a) sundial
(b) stop watch
(c) simple pendulum
(d) sand clock

9. A particle vibrates 10 times in 1 sec. What is the time period of vibration of the particle?

(a) 10 sec
(b) 1 sec
(c) 0.1 sec
(d) 0.01 sec

10. The rate of change of displacement is called

(a) velocity
(b) Acceleration
(c) Rest
(d) Motio

11.  The speed of the vehicle is recorded by

(a) Ammeter
(b) Odometer
(c) Speedometer
(d) Voltmeter

12. The clock used now a days are:

(a) quartz
(b) minute
(c) second
(d) all of these

13. Physical quantity which we can’t obtain from a distance- time graph is

(a) speed
(b) time taken
(c) change in position
(d) Velocity

 14. A horse pulling a cart has:

(a) oscillatory motion
(b) circular motion
(c) linear motion
(d) none of these

15.  If the velocity of a body does not change with time, its acceleration is

(a) zero
(b) infinite
(c) unity
(d) None of these 

16. The distance travelled by the vehicles is recorded by

(a) monometer
(b) odometer
(c) speedometer
(d) motometer

17. The times taken by a pendulum to complete one oscillation is:

(a) oscillation period
(b) 1 second
(c) time period
(d) frequency

18. Watch used to measure short interval of time is

(a) Stop watch
(b) Pendulum watch
(c) Atom watch
(d) Quartz watch

19. If the speed of an object along a straight line keeps changing, its motion is said to be

(a) uniform motion
(b) non-uniform motion
(c) linear motion
(d) none of these

20. The time taken by a pendulum of given length to complete one oscillation is

(a) Different at different times
(b) Same at all times
(c) Increases at different times
(d) Decreases at different times

21. The to and fro motion of the particle about its mean position is called:

(a) intervals
(b) vibration
(c) pendulum
(d) can’t say

22. The distance-time graph of an object under uniform motion is a

(a) curved line
(b) straight line
(c) circle
(d) parabola

23.  The correct symbol to represent the speed of an object is:

(a) 5 m/s
(b) 5 mp
(c) 5 m/s-1
(d) 5 s/m

24. The basic unit of speed is 

(a) Km/min
(b) m/min
(c) km/h
(d) m/s  

25. An ancient Time measuring device SUNDIAL at Jantar Mantar is in

(a) Ahmedabad
(b) Bombay
(c) Jaipur
(d) Lucknow

Answer:

1. Answer: (b) 10 m/s

Explanation: Distance = 54 km

= 54 × 1000 m

Distance = 54000 m

Time = 90 minutes

 = 90 × 60

Time = 5400s

Therefore,

Distance = 54000m

Time = 5400s

Speed = Distance / Time

Speed = 54000/5400

Speed = 10 m/s

2. Answer: (d) circular periodic motion

Explanation: All the clocks around the world are manufactured to show some circular periodic motion so that the accurate type of time measurement can be featured in all the clocks.

3. Answer: (a) 1.6 s

Explanation: Time taken to complete 20 oscillations =32s

Time taken to complete 1 oscillation = 32/20s = 1.6s

Time period of a pendulum is time taken by it to complete 1 oscillation.

Time period of pendulum is 1.6 seconds.

4. Answer: (b) length

Explanation:The time period of the simple pendulum depends upon the length of the pendulum and also to some extent it depends upon the degree of the amplitude. That is the width of the pendulum's swing. In general, the time period of a pendulum means one complete cycle that is one complete left swing and right swing.

5. Answer: (d) Blinking of eyes

Explanation: Blinking of eye is not a periodic phenomenon. Eyes does not blink at a fixed interval of time. Hence Blinking of eyes cannot be used for measurement of time.

6. Answer: (b) y-axis

Explanation: The independent variable belongs on the x-axis (horizontal line) of the graph and the dependent variable belongs on the y-axis (vertical line).

7. Answer: (b) 7.2

Explanation: Boojho Home to school to again home

From home to school distance is 3 km time taken is 30 min = (30/60) hour = 0.5 hour

And in returning from school to home time taken = 20 min = (20/60) hour = 0.33 hour

average speed = Total distance / time taken

= (3 + 3)/(0.5 + 0.33) km/h

= 7.2 km/h

8. Answer: (c) simple pendulum

Explanation: One of the most well-known periodic motions is that of a simple pendulum. A simple pendulum consists of a small metallic ball or a piece of stone suspended from a rigid stand by a thread.

9. Answer: (c) 0.1 sec

Explanation: Time period of vibration is the time taken for 1 vibration.

Given:

10 vibrations are completed in 1 sec.

1 vibration will taken only: 1/10 = 0.1 sec

10. Answer: (a) velocity

Explanation: The rate of change of displacement is called velocity.

11. Answer: (c) Speedometer

Explanation: Speedometer, instrument that indicates the speed of a vehicle, usually combined with a device known as an odometer that records the distance traveled.

12. Answer: (a) quartz

Explanation: These clocks are called quartz clocks. The time measured by quartz clocks is much more accurate than that by the clocks available earlier.

13. Answer: (d) Velocity

Explanation: Velocity is that physical quantity which can be calculated by finding the slope of a distance-time graph.

 14. Answer: (a) oscillatory motion 

Explanation: During running the hands move to and fro and as this motion gets repeated after certain time interval. Therefore it is oscillatory motion.

15.  Answer: (a) zero

Explanation: Acceleration has to do with changing how fast an object is moving. If an object is not changing its velocity, then the object is not accelerating.

16. Answer: (b) odometer

Explanation: speedometer, instrument that indicates the speed of a vehicle, usually combined with a device known as an odometer that records the distance traveled.

17. Answer: (c) time period

Explanation: Time period of a pendulum is defined the time taken by it to complete one oscillation. Time period of simple pendulum \(T=2\pi\sqrt{\frac{l}{g}}\) where l is the length of pendulum string and g is the acceleration due to gravity.

18. Answer: (a) Stop watch

Explanation: The stopwatch is used to measure short time intervals.

19. Answer: (b) non-uniform motion

Explanation: If the speed of an object moving along a straight line keeps changing, its motion is said to be non uniform motion.

20. Answer: (b) Same at all times 

Explanation: The time taken by a pendulum of a given length to complete one oscillation is same at all times. The time period of a pendulum to complete one oscillation it is dependent on the acceleration due to gravity and the length.

21. Answer: (b) vibration

Explanation: To and fro motion of a particle about mean position is called vibrational motion.

22. Answer: (b) straight line

Explanation: The distance-time graph of an object moving with a uniform speed (or constant speed) is a straight line.

23. Answer: (a) 5 m/s

Explanation: Velocity is rate of change of displacement with respect to time.

Velocity V = D/T

So, unit of velocity = m/s

24. Answer: (d) m/s  

Explanation: The unit of distance is the metre (m) and of time is second(s). Therefore the basic unit of speed is m/s.

25. Answer: (c) Jaipur

Explanation: The World's Largest Sundial in Jaipur has been telling time for almost 300 years.

Click here for Practice MCQ Questions for Motion and Time Class 7

All of the Class 10 Science MCQ Questions of Acids, Bases and Salts are given precise Answer. This series of Multiple choice questions will allow class 10 students an opportunity to test their insight into ideas and assist them with getting prepared for the impending CBSE Exam. 

 Class 10 MCQ Questions Acids, Bases and Salts

Check underneath the MCQ Questions of Acids, Bases and Salts with Answer for speedy amendment of key ideas: -

1. The nature of calcium phosphate is present in tooth enamel is

(a) Basic
(b) Amphoteric
(c) Acidic
(d) Neutral

2. NaHCO, formed by reaction of

(a) \(NaOH + H_2CO_3\)
(b) \(NaCl + H_2CO_3\)
(c) \(Na_2CO_3 + HCl\)
(d) \(NaOH + Na_2CO_3\)

3. Calcium phosphate is present in tooth enamel. Its nature is

(a) basic
(b) acidic
(c) neutral
(d) amphoteric

4. Which of the following does not form an acidic salt?

(a) Phosphoric acid
(b) Carbonic acid
(c) Hydrochloric acid
(d) Sulphuric acid

5. The chemical formula of caustic potash is

(a) \(NaOH\)
(b) \(Ca(OH)_2\)
(c) \(NH_4OH\)
(d) \(KOH\)

6. Which one of the following is acidic?

(a) Lemon juice
(b) Tomatoes
(c) Milk
(d) All

7. An aqueous solution turns red litmus solution blue. Excess addition of which of the following solution would reverse the change?

(a) Baking power
(b) Lime
(c) Ammonium hydroxide solution
(d) Hydrochloric acid

8. Which one of the following types of medicines is used for treating indigestion?

(a) Antibiotics
(b) Analgesic
(c) Antacid
(d) Antiseptic

9. Butyric acid is found in

(a) Rancid butter
(b) Rancid cake
(c) Stings of bees
(d) All of these

10. An indicator is one kind of the following compound

(a) Strong acid only
(b) Reducing agent
(c) Weak base or acid only
(d) Complex salt

11. Assertion: Universal indicator gives green colour with distilled water.

Reason: pH of distilled water is 7 and it is neutral and universal indicator gives green colour with neutral solution.

(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
(e) Both A and R are false.

12. When a bee stings, immediately a paste of lime is put on the sting. Why?

(a) Bee sting is made of a base
(b) Bee sting contains an acid called formic acid. It gets neutralised with CaO.
(c) Bee sting is acidic due to hydrochloric acid and this is neutralised
(d) All of the above.

13. Sodium hydroxide turns phenolphthalein solution

(a) pink
(b) yellow
(c) colourless
(d) orange

14. PH scale of a neutral solution is

(a) 14
(b) 7
(c) 10
(d) 12

15. At what temperature is gypsum heated to form Plaster of Paris?

(a) 90°C
(b) 100°C
(c) 110°C
(d) 120°C

16. Sodium carbonate is a basic salt because it is a salt of

(a) strong acid and strong base
(b) weak acid and weak base
(c) strong acid and weak base
(d) weak acid and strong base

17. What is the pH range of human body?

(a) 7.0 – 7.8
(b) 7.2 – 8.0
(c) 7.0 – 8.4
(d) 7.2 – 8.4

18. Which of the following gives the correct increasing order of acidic strength?

(a) Water < Acetic acid < Hydrochloric acid
(b) Water < Hydrochloric acid < Acetic acid
(c) Acetic acid < Water < Hydrochloric acid
(d) Hydrochloric acid < Water < Acetic acid

19. Acids react with bases to form salt and water. This reaction is known as:

(a) Combination
(b) Decomposition
(c) Neutralisation
(d) reduction

20. Acids react with metals to liberate _________gas

(a) Carbon dioxide
(b) Carbon monoxide
(c) Hydrogen
(d) Water

Answer Key

1. (a) Basic
2. (a) \(NaOH + H_2CO_3\) 
3. (a) basic
4. (b) Carbonic acid
5. (d) \(KOH\)
6. (d) All
7. (d) Hydrochloric acid
8. (c) Antacid
9. (b) Rancid cake
10. (c) Weak base or acid only
11. (a) Both A and R are true and R is the correct explanation of A.
12. (b) Bee sting contains an acid called formic acid. It gets neutralised with CaO.
13. (a) pink
14. (b) 7
15. (b) 100°C
16. (d) weak acid and strong base
17. (a) 7.0 – 7.8
18. (a) Water < Acetic acid < Hydrochloric acid
19. (c) Neutralisation
20. (c) Hydrogen

Click here to practice more MCQ Questions from Chapter Acids, Bases and Salts Class 10 Science

The name of the genus begins with a capital letter. 

The name of the species begins with a small letter. 

Example : Naja naja, Pila globosa

Elements present in the same group show same chemical properties.

We have Provided Class 10 MCQ Questions of Chemical Reactions and Equations to help students with understanding the concept very well. Students can tackle Class 10 Science Multiple Choice Questions with Answers to realize their preparation level.

Practice Class 10 Science MCQ Questions of Chemical Reactions and Equations

Check the underneath MCQ Questions of Chemical Reactions and Equations with Answer: -

1. The reaction between lead nitrate and potassium iodide present in aqueous solutions is an example of

(a) Decomposition Reaction
(b) Displacement Reaction
(c) Double Displacement Reaction
(d) Neutralisation Reaction

2. Fatty foods become rancid due to the process of

(a) oxidation
(b) corrosion
(c) reduction
(d) hydrogenation

3. Assertion: A lead nitrate on thermal decomposition gives lead oxide, brown coloured nitrogen dioxide and oxygen gas.

Reason: Lead nitrate reacts with potassium iodide to form yellow ppt of lead iodide and the reaction is double displacement as well as precipitation reaction.

(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
(e) Both A and R are false.

4. Silver article turns black when kept in the open for a few days due to formation of
(a) \(H_2S\)
(b) \(AgS\)
(c) \(AgSO_4\)
(d) \(Ag_2S\)

5. Reaction of ‘magnesium’ with air is

(A) Exothermic reaction
(B) Endothermic reaction
(C) Reversible reaction
(D) Substitution reaction

6. What type of chemical reactions take place when electricity is passed through water?

(a) Displacement
(b) Combination
(c) Decomposition
(d) Double displacement

7. In an electrolytic cell where electrolysis is carried, anode has:
(a) Positive change
(b) Negative charge
(c) Connected to negative terminal of the battery
(d) None of these is correct

8. On immersing an iron nail in \(CuSO_4\) solution for few minutes, you will observe

(a) no reaction takes place
(b) the colour of solution fades away
(c) the surface of iron nails acquire a black coating
(d) the colour of solution changes to green

9. Which of the given gases can be used for storage of fresh samples of an oil for a long time?

(A) Carbon dioxide or oxygen
(B) Nitrogen or helium
(C) Helium or oxygen
(D) Nitrogen or oxygen

10. Rancidity can be prevented by

(a) adding antioxidants
(b) storing food away from light
(c) keeping food in refrigerator
(d) all of these

11. In which of the following, heat energy will be evolved?

(a) Electrolysis of water
(b) Dissolution of \(NH_4Cl\) in water
(c) Burning of L.P.G.
(d) Decomposition of AgBr in the presence of sunlight

12. What is the other name for quick lime?

(A) Calcium hydroxide
(B) Calcium oxide
(C) Carbon dioxide
(D) Sodium oxide

13. Both \(CO_2\) and \(H_2\) gases are

(A) Heavier than air
(B) Colourless
(C) Acidic in nature
(D) Soluble in water

14. Which of the following are exothermic processes?

(i) Reaction of water with quick lime
(ii) Dilution of an acid
(iii) Evaporation of water
(iv) Sublimation of camphor (crystals)

(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (iii) and (iv)

15. The reaction of acetylene and hydrogen in presence of heated nickel powder is called:

(a) Substitution
(b) Dissociation
(c) Addition
(d) Decomposition.

16. Which of the following is not a physical change?

(a) Boiling of water to give water vapour
(b) Melting of ice to give water
(c) Dissolution of salt in water
(d) Combustion of Liquefied Petroleum Gas (LPG)

17. What happens when dilute Sulphuric acid is added to Zn granules?

(a) Hydrogen gas and Zinc chloride are produced.
(b) Chlorine gas and Zinc hydroxide are produced.
(c) No reaction takes place.
(d) Zinc salt and water are produced.

18. A teacher gave two test tubes to the students, one containing water and the other containing sodium hydroxide. She asked them to identify the test tube containing sodium hydroxide solution. Which one of the following can be used for the identification?

(a) Blue litmus
(b) Red litmus
(c) Sodium carbonate solution
(d) Dilute hydrochloric acid

19. The substitution is characteristic of:

(a) Alkenes
(b) Alkynes
(c) Carbon monoxide
(d) Paraffins.

20. What type of reaction is respiration

(a) Exothermic
(b) Endothermic
(c) Reduction reaction
(d) Combination reaction

Answer Key

1. (c) Double Displacement Reaction
2. (a) oxidation
3. (b) Both A and R are true but R is not the correct explanation of A.
4. (d) \(Ag_2S\)
5. (A) Exothermic reaction
6. (c) Decomposition
7. (a) Positive change
8. (d) the colour of solution changes to green
9. (B) Nitrogen or helium
10. (d) all of these
11. (c)  Burning of L.P.G.
12. (B) Calcium oxide
13. (B) Colourless
14. (a) (i) and (ii)
15. (c) Addition
16. (d) Combustion of Liquefied Petroleum Gas (LPG)
17. (a) Hydrogen gas and Zinc chloride are produced.
18. (b) Red litmus
19. (d) Paraffins.
20. (a) Exothermic

Click here to practice more MCQ Questions from Chapter Chemical Reactions and Equations Class 10 Science

Conventions used in writing a chemical equation: 

(1) The reactants are written on the left hand side (LHS), while the products are written on the right hand side (RHS).

(2) Whenever there are two or more reactants, a plus sign (+) is written between each two of them. Similarly, if there are two or more products, a plus sign is written between each two of them.

(3) Reactant side and product side are connected with an arrow (→) pointing from reactants to products. The arrow represents the direction of the reaction. Heat is to be given from outside to the reaction, it is indicated by the sign Δ written above the arrow.

(4) The conditions like temperature, pressure, catalyst, etc., are mentioned above the arrow (→) pointing towards the product side.

(5) The physical states of the reactants and products are also mentioned in a chemical equation. The notations g, l, s, and aq are written in brackets as a subscript along with the symbols / formulae of reactants and products. The symbols g, l, s, and aq stand for gaseous, 1iquid. solid and aqueous respectively.

If the product is gaseous, instead of (g) it can be indicated by an arrow ↑ pointing upwards. If the product formed is insoluble solid, then instead of (s) it can be indicated by an arrow ↓ pointing downwards.

(6) Special information or names of reactants/products are written below their formulae.

The blackened silver utensils and patinated (greenish) brass utensils are cleaned using baking soda, vinegar and lemon mix.

D) ‘A’ is incorrect, ‘R’ is correct.

while writing the molecular formulae of different compounds, the symbol of the radicals and their valence should be known. The number of the ions is written as subscript on the right of the symbol or the ion. By cross multiplication of valenceies chemical formula is obtained.

C) The total mass of the products = total mass of the reactants.

D) both ‘a’ and ‘b’ are incorrect

The chemical formula of a substance is the symbolic representation of the actual number of atoms present in one molecule of that substance.

(a) Formula of one molecule of water is H₂O. It shows that one molecule of water is made up of 2 atoms of hydrogen and one atom of oxygen.

(b) Formula of one molecule of sulphuric acid is H₂SO₄. It shows that one molecule of sulphuric acid is made up of 2 atoms of hydrogen, 1 atom of Sulphur and 4 atoms of oxygen.

Chemical combination: It is a reaction in which two or more substances combine to form a single substance

A chemical equation is balanced so that the number of atoms of each type involved in a chemical reaction is the same on the reactant and product sides of the equation.

(B) (ii) only

(a) Balanced; Combination reaction 

(b) \(2HgO(s)\overset{Heat}\rightarrow 2Hg(l) + O_2(g)\)

Decomposition reaction

(c) \(2Na(s) + S(s)\overset{Fuse}\rightarrow Na_2S(s)\)

Combination reaction 

(d) TiCl₄ (l) + 2Mg (s) →Ti (s) + 2MgCl₂ (s)

Displacement reaction

(e) Balanced; Combination reaction 

(f) \(2H_2O_2(l)\overset{U.V}\rightarrow 2H_2O(l)+O_2(g)\)

Decomposition reaction

Chemical change: - is a change in which one or more new substances are formed. In a chemical change—

• New substances are formed.

• Energy changes are involved.

• There is a change in mass during the reaction.

• Permanent change takes place.

Examples –

❖ Cooking of food

❖ Rusting of iron

❖ Heating of Lead nitrate

❖ Souring of milk

❖ Ripening of fruit.

Rusting of iron is a chemical change because

❖ A new substance iron oxide is formed.

❖ The change is permanent; the article has got a rust layer (which may only peal off).

❖ There is an increase in mass when rust forms.

❖ An energy change has taken place (which may not be visible).

Law of conservation of mass. 

Mass can neither be created nor be destroyed during a chemical reaction

Rusting of iron

Atmolysis is the process of separation of two gases on the basis of their different rates of diffusion due to difference in their densities is called atmolysis. It has been applied with success for the separation of isotopes and other gaseous mixtures.

The atmospheric pressure is less and so the boiling point is lowered.

ΔH_vap / Tb = 21 cal K^-1 mol^-1 (Trouton’s rule)

The temperature at which the volume of a gas becomes equal to zero is called Absolute Zero.