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Class 11 Physics MCQ Questions of Kinetic Theory with Answers?

Answer 1

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We have assembled the NCERT Class 11 Physics MCQ Questions of Kinetic Theory with Answer. It's covering the whole syllabus. Practice MCQ Questions for Class 11 Physics with Answers consistently and score well in tests. Allude to the Kinetic Theory Class 11 Multiple Choice Questions with Answers here alongside a definite clarification. 

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Practice MCQ Questions for class 11 Physics Chapter-Wise

1. Real gases show markable deviation from that of ideal gas behavior at

(a) High temperature and low pressure
(b) Low temperature and high pressure
(c) High temperature and high pressure
(d) Low temperature and low pressure

2. A room temperature the r.m.s. velocity of the molecules of a certain diatomic gas is found to be 1930 m/sec. the gas is

(a) H₂
(b) F₂
(c) O₂
(d) Cl₂ 

3. Moon has no atmosphere because

(a) It is far away form the surface of the earth
(b) Its surface temperature is 10°C
(c) The r.m.s. velocity of all the gas molecules is more then the escape velocity of the moons surface
(d) The escape velocity of the moons surface is more than the r.m.s velocity of all molecules

4. Latent heat of ice is

(a) 336 kJ kg ⁻¹
(b) 663 kJ kg ⁻¹
(c) 363 kJ kg ⁻¹
(d) 636 kJ kg ⁻¹

5. Energy supplied to convert unit mass of substance from solid to liquid state at its melting point is called

(a) Latent heat of fusion
(b) Evaporation
(c) Solidification
(d) Latent heat of fission

6. An ideal gas is that which can

(a) Be solidified
(b) Liquefied
(c) Not be liquefied
(d) Not be solidified

7. One mole of an ideal gas requires 207 J heat to raise the temperature by 10 K, when heated at constant pressure. If the same gas is heated at constant volume to raise the temperature by 10K, then heat required is

(a) 96.6 J
(b) 124 J
(c) 198.8 J
(d) 215.4 J

8. When 20 cal of heat is supplied to a system, the increase in internal energy is 50 J. If the external work done is 35 J, the mechanical equivalent of heat is:

(a) 4.25 J/cal
(b) 1.26 J/cal
(c) 4.92 J/cal
(d) 2.1 J/cal

9. Average kinetic energy of molecules is

(a) Directly proportional to square root of temperature
(b) Directly proportional to absolute temperature
(c) Independent of absolute temperature
(d) Inversely proportional to absolute temperature

10. Following gases are kept at the same temperature. Which gas possesses maximum r.m.s. speed?

(a) Oxygen
(b) Nitrogen
(c) Hydrogen
(d) Carbon dioxide

11. According to kinetic theory of gases, at absolute zero of temperature

(a) Water freezes
(b) Liquid helium freezes
(c) Molecular motion stops
(d) Liquid hydrogen freezes

12. Kinetic theory of gases provide a base for

(a) Both Charle’s law and Boyle’s law
(b) None of these
(c) Boyle’s law
(d) Charle’s law

13. According to the kinetic theory of gases, the pressure exerted by a gas on the wall of the container is measured as

(a) rate of change of momentum imparted to the walls per second per unit area
(b) momentum imparted to the walls per unit area
(c) change of momentum imparted to the walls per unit area
(d) change in momentum per unit volume

14. When a gas is in thermal equilibrium, its molecules

(a) have the same average kinetic energy of molecules
(b) have different energies which remain constant
(c) have a certain constant energy
(d) do not collide with one another

15. Molecules of a ideal gas behave like

(a) perfectly elastic rigid sphere
(b) inelastic non-rigid sphere
(c) perfectly elastic non-rigid sphere
(d) inelastic rigid sphere

16. In kinetic theory of gases, it is assumed that molecules

(a) have same mass but negligible volume
(b) have different mass as well as volume
(c) have same volume but mass can be different
(d) have same mass but can have different volume.

17. The internal energy of a gram-molecule of an ideal gas depends on

(a) pressure alone
(b) volume alone
(c) temperature alone
(d) both on pressure as well as temperature

18. The phenomenon of Browninan  movement may be taken as evidence of

(a) kinetic theory of matter
(b) electromagnetic theory of radiation
(c) corpuscular theory of light
(d) photoelectric phenomenon

19. At a given temperature the force between molecules of a gas as a function of intermolecular distance is

(a) first decreases and then increases
(b) always increases
(c) always decreases
(d) photoelectric phenomenon

20. For Boyle’s law to hold, the gas should be

(a) perfect and of constant mass and temperature
(b) real and of constant mass and temperature
(c) perfect and constant temperature but variable mass
(d) real and constant temperature but variable mass

21. Boyle' law is applicable for an

(a) isothermal process
(b) isochoric process
(c) adiabatic process
(d) isobaric process

22. The deviation of gases from the behaviour of ideal gas is due to

(a) attraction of molecules
(b) absolute scale of temp
(c) covalent bonding of molecules
(d) colourless molecules

23. Kinetic energy of a gas molecule depends on:

(a) Pressure 
(b) Volume
(c) Temperature
(d) All the above

24. Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside wil

(a) remains the same
(b) Volume
(c) Temperature
(d) All the above

25. A diatomic molecule has how many degrees of freedom

(a) 3
(b) 4
(c) 5
(d) 6

Answer 2

1. Answer: (a) High temperature and low pressure

Explanation: Real gases approach ideal gas behaviour at high temperature and low pressure because at high pressures and low temperature, molecules of gases are very close to each other.

2. Answer: (a) H₂

Explanation: \(v_{rms}=\sqrt\frac{3RT}{M}\)

Room temperature, T \(\approx\) 300 K

\(1930=\sqrt\frac{3\times8.31\times10^3\times300}{M}\)

M = 2 g or the gas is H₂.

3. Answer: (c) The r.m.s. velocity of all the gas molecules is more then the escape velocity of the moons surface

Explanation: The escape velocity (the minimum velocity with which a body is to be projected so as to escape from the gravitational pull) on the surface of moon is very much less than  the rms velocity of the molecules of gas at the surface temperature of moon. Therefore, the molecules will escape and therefore moon cannot hold an atmosphere. 

4. Answer: (a) 336 kJ kg ⁻¹

Explanation: Latent heat is the heat required to change the unit mass of substance. The latent heat of ice is  336 kJ kg ⁻¹

5. Answer: (a) Latent heat of fusion

Explanation: The heat energy supplied per unit mass of a substance at its melting point to convert the state of the substance from solid to liquid is known as Latent heat of Fusion.

6. Answer: (c) Not be liquefied

Explanation: The concept of liquefaction of gases works on the principle of intermolecular forces of attraction between the gas molecules. Gases liquefy when these forces increase between the molecules, binding them together. But an ideal gas is one where the molecules do not influence each other, the explanation comes from Joule Thompson effect.

7. Answer: (b) 124 J

Explanation: Using C_P − C_V =R,

C_P is heat needed for raising by 10 K.

∴C_P =20.7J/moleK

Given R = 8.3 J/mole K

∴C_V = 20.7 − 8.3 = 12.4J/moleK

∴ For raising by 10 K. = 124 J.

8. Answer: (a) 4.25 J/cal

Explanation: According to first law of thermodynamics JΔQ = ΔW + ΔU, where J is the mechanical equivalent of heat.

J \(\times\) 20 = 50 + 35

J = 4.25J/cal

9. Answer: (b) Directly proportional to absolute temperature

Explanation: The average kinetic energy of all the molecules is assumed to be directly proportional to the absolute temperature of the gas. This means that molecules of different gases at the same temperature have the same average kinetic energy.

10. Answer: (c) Hydrogen

Explanation: The root mean square velocity of a gas is given by:

\(V_{rms}=\sqrt\frac{3RT}{M}\)

For a given temperature, RMS velocity is inversely proportional to molecular mass. Hence the one with smallest molecular mass has the highest RMS velocity.

11. Answer: (c) Molecular motion stops

Explanation: According to classical theory all motion of molecules stop at 0 K.

12. Answer: (a) Both Charle’s law and Boyle’s law

Explanation: Kinetic Molecular Theory states that gas particles are in constant motion and exhibit perfectly elastic collisions. Kinetic Molecular Theory can be used to explain both Charles' and Boyle's Laws. The average kinetic energy of a collection of gas particles is directly proportional to absolute temperature only.

13. Answer: (a) rate of change of momentum imparted to the walls per second per unit area

Explanation: Particles impart momentum on the wall. And the rate of change of momentum is the force exerted on the wall. Pressure is force per unit area. Hence pressure exerted by gas on the wall is the rate of change of momentum imparted to the walls per second per unit area.

14. Answer: (a) have the same average kinetic energy of molecules

Explanation: When a gas is in thermal equilibrium, the temperature throughout the gas is the same. (Zeroth law of thermodynamics).The average kinetic energy of the gas molecules is directly proportional to the absolute temperature of the gas. i.e. different sections of the gas will all have the same average kinetic energy.

Answer 3

15. Answer: (a) perfectly elastic rigid sphere

Explanation: According to kinetic theory of gases, gas molecules behave as a perfectly elastic rigid spheres.

16. Answer: (d) have same mass but can have different volume

Explanation: In kinetic theory of gas, if is assumed that molecules/atoms have negligible volume.

17. Answer: (a) pressure alone

Explanation: The internal energy of an ideal gas is given by the expression : U = C_vT. From the above expression its clear that internal energy depend only on temperature.

18. Answer: (a) kinetic theory of matter

Explanation: The phenomenon of Brownian movement is related with the motion of molecules which is related to the kinetic theory of matter.

19. Answer: (a) first decreases and then increases  

Explanation: In a gas the average kinetic energy of the particles is high enough to overcome the forces of attraction between them so the molecules move apart when they collide. ... At a given temperature the force between molecules of a gas as a function of intermolecular distance first decreases and then increases.

20. Answer: (a) perfect and of constant mass and temperature

Explanation: To obey boyles law gas must be ideal or perfect and its mass or no of moles must be same and temperature must be constant

PV=nRT if n=constant and T=constant then only PV = constant

21. Answer: (a) isothermal process

Explanation: Boyle's law: For a given mass of an ideal gas at constant temperature, the volume of a gas is inversely proportional to its pressure. So we can say that when temperature is constant, Boyle's law is applicable. So, this law is applicable for an isothermal process, in which temperature remain constant.

22. Answer: (a) attraction of molecules

Explanation: For ideal behaviour we assume there is no attractive force between molecules of gas but there is an attractive force which produces non ideality.

23. Answer: (c) Temperature

Explanation: According to kinetic theory, "the average kinetic energy of gas molecules depends upon the absolute temperature. At any given temperature, the molecules of all gases have the same average kinetic energy".

24. Answer: (a) remains the same

Explanation: Since the pressure and volume of gas remains same , therefore , there will not be any change in the temperature of the gas molecules.

25. Answer: (c) 5

Explanation: Number of degree of freedom .

d=3N−1

where N is the number of atoms in a molecules

In diatomic molecules,  N=2

⟹ d = 3(2)−1

= 5

Hence diatomic molecule has 5 degrees of freedom (3 translational and 2 rotational).

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