# MCQs For NCERT Class 11 Physics Chapter 13 Kinetic Theory

Please refer to the MCQ Questions for Class 11 Physics Chapter 13 Kinetic Theory with Answers. The following Kinetic Theory Class 11 Physics MCQ Questions have been designed based on the latest syllabus and examination pattern for Class 11. Our experts have designed MCQ Questions for Class 11 Physics with Answers for all chapters in your NCERT Class 11 Physics book.

## Kinetic Theory Class 11 MCQ Questions with Answers

See below Kinetic Theory Class 11 Physics MCQ Questions, solve the questions and compare your answers with the solutions provided below.

Question. Helium gas is filled in a closed vessel (having negligible thermal expansion coefficient) when it is heated from 300 K to 600 K, then average kinetic energy of helium atom will be
(a) √2 times
(b) 2 times
(c) unchanged
(d) half

B

Question. How many degrees of freedom are associated with 2 grams of He at NTP ?
(a) 3
(b) 3.01 × 1023
(c) 9.03 × 1023
(d) 6

C

Question. If 2 mole of an ideal monatomic gas at temperature T0 is mixed with 4 moles of another ideal monatomic gas at temperature 2T0, then the temperature of the mixture is
(a) (5/3)T0
(b) (3/2)T0
(c) (4/3)T0
(d) (5/4)T0

A

Question. The temperature at which the root mean square velocity of the gas molecules would become twice of its value at 0°C is
(a) 819°C
(b) 1092°C
(c) 1100°C
(d) 1400°C

A

Question. At what temperature is the r.m.s. velocity of a hydrogen molecule equal to that of an oxygen molecule at 47ºC
(a) 80 K
(b) –73 K
(c) 3 K
(d) 20 K

D

Question. One litre of oxygen at a pressure of 1 atm, and 2 litres of nitrogen at a pressure of 0.5 atm. are introduced in the vessel of 1 litre capacity, without any change in temperature. The total pressure would be
(a) 1.5 atm.
(b) 0.5 atm.
(c) 2.0 atm.
(d) 1.0 atm.

C

Question. The air in a room has 15 gm of water vapours per cubic metre of its volume. However for saturation one cubic metre of volume requires 20 gm of water vapour then relative
humidity is
(a) 50%
(b) 75%
(c) 20%
(d) 25%

B

Question. A vessel contains air at a temperature of 15ºC and 60% R.H.
What will be the R.H. if it is heated to 20ºC? (S.V.P. at 15ºC is 12.67 & at 20ºC is 17.36mm of Hg respectively)
(a) 262%
(b) 26.2%
(c) 44.5%
(d) 46.2%

C

Question. To what temperature should be the hydrogen at 327°C be cooked at constant pressure so that the root mean square velocity of its molecules becomes half of its previous value
(a) –123°C
(b) 120°C
(c) –100°C
(d) 0°C

A

Question. If pressure of a gas contained in a closed vessel is increased by 0.4% when heated by 1ºC, the initial temperature must be
(a) 250 K
(b) 250ºC
(c) 2500 K
(d) 25ºC

A

Question. N molecules, each of mass m, of gas A and 2 N molecules,each of mass 2 m, of gas B are contained in the same vessel which is maintained at a temperature T. The mean square of the velocity of molecules of B type is denoted by v2 and the mean square of the X component of the velocity of A type is dentoed by w2, w2/v2 is
(a) 2
(b) 1
(c) 1/3
(d) 2/3

D

Question. At what temperature, pressure remaining constant, will the r.m.s. velocity of a gas be half of its value at 0ºC?
(a) 0ºC
(b) –273ºC
(c) 32ºC
(d) –204ºC

D

Question. The order of magnitude of the number of nitrogen molecules in an air bubble of diameter 2 mm under ordinary conditions is
(a) 105
(b) 109
(c) 1013
(d) 1017

D

Question. At identical temperatures, the rms speed of hydrogen molecules is 4 times that for oxygen molecules. In a mixture of these in mass ratio H2 : O2 = 1:8, the rms speed of all molecules is n times the rms speed for O2 molecules, where n is
(a) 3
(b) 4/3
(c) (8/3)1/2
(d) (11)1/2

D

Question. In Vander Waal’s equation the critical pressure Pc is given by
(a) 3 b
(b) a/27 b2
(c) 27a / b2
(d) b2/a

B

Question. 1 mole of a gas with γ = 7/5 is mixed with 1 mole of a gas with γ = 5/3, then the value of g for the resulting mixture is
(a) 7/5
(b) 2/5
(c) 24/16
(d) 12/7

C

Question. Two identical containers A and B with frictionless pistons contain the ideal gas at the same temperature and the same volume V. The mass of the gas in A is mA and in B is mB. The gas in each cylinder is now allowed to expand isothermally to the same final volume 2V. The changes in pressure in A and B are found to be Dp and 1.5DP respectively.
(a) 4mA = 9mB
(b) 2mA = 3mB
(c) 3mA = 2mB
(d) 9mA = 4mB

C

Question. At what temperature the molecules of nitrogen will have the same rms velocity as the molecules of oxygen at 127°
(a) 457° C
(b) 273° C
(c) 350° C
(d) 77° C

C

Question. If the root mean square velocity of the molecules of hydrogen at NTP is 1.84 km/s. Calculate the root mean square velocity of oxygen molecule at NTP, molecular weight of hydrogen and oxygen are 2 and 32 respectively
(a) 1.47 km/sec
(b) 0.94 km/s
(c) 1.84 km/s
(d) 0.47 km/sec

D

Question. N molecules, each of mass m, of gas A and 2 N molecules, each of mass 2 m, of gas B are contained in the same vessel which is maintained at a temperature T. The mean square velocity of molecules of B type is denoted by V2 and the mean square velocity of A type is denoted by V1, then V1 /V2 is
(a) 2
(b) 1
(c) 1/3
(d) 2/3

B

Question. An ideal gas is found to obey an additional law VP2 =constant. The gas is initially at temperature T and volume V. When it expands to a volume 2 V, the temperature becomes
(a) T /√2
(b) 2 T
(c) 2T√2
(d) 4 T

A

Question. Two monatomic ideal gases 1 and 2 of molecular masses m1 and m2 respectively are enclosed in separate containers kept at the same temperature. The ratio of the speed of sound in gas 1 to that in gas 2 is given by
(a) √(m1 /m2)
(b) √(m2 /m1)
(c) m1 /m2
(d) m2 /m1

A

Question. If the potential energy of a gas molecule is U = M/r6 – N/r12, M and N being positive constants, then the potential energy at equilibrium must be
(a) zero
(b) M2/4N
(c) N2/4M
(d) MN2/4

B

Question. Air is pumped into an automobile tube upto a pressure of 200 kPa in the morning when the air temperature is 22°C.
During the day, temperature rises to 42°C and the tube expands by 2%. The pressure of the air in the tube at this temperature, will be approximately
(a) 212 kPa
(b) 209 kPa
(c) 206 kPa
(d) 200 kPa

B

Question. A gas mixture consists of 2 moles of oxygen and 4 moles of Argon at temperature T. Neglecting all vibrational moles, the total internal energy of the system is
(a) 4 RT
(b) 15 RT
(c) 9 RT
(d) 11RT

D

Question. The molar heat capacities of a mixture of two gases at constant volume is 13R/6. The ratio of number of moles of the first gas to the second is 1 : 2. The respective gases may be
(a) O2 and N2
(b) He and Ne
(c) He and N2
(d) N2 and He

C

Question. A graph is plotted with PV/T on y-axis and mass of the gas along x-axis for different gases. The graph is
(a) a straight line parallel to x-axis for all the gases
(b) a straight line passing through origin with a slope having a constant value for all the gases
(c) a straight line passing through origin with a slope  having different values for different gases
(d) a straight line parallel to y-axis for all the gases

C

Question. Four mole of hydrogen, two mole of helium and one mole of water vapour form an ideal gas mixture. What is the molar specific heat at constant pressure of mixture?
(a) (16/7 )R
(b) (7/16)R
(c) R
(d) (23/7)R

D

Question. One mole of a gas occupies 22.4 lit at N.T.P. Calculate the difference between two molar specific heats of the gas.
J = 4200 J/kcal.
(a) 1.979 k cal/kmol K
(b) 2.378 k cal/kmol K
(c) 4.569 kcal/kmol K
(d) 3.028 k cal/ kmol K

A

Question. Four molecules have speeds 2 km/sec, 3 km/sec, 4 km/sec and 5 km/sec. The root mean square speed of these molecules (in km/sec) is
(a) √54 / 4
(b) √54 / 2
(c) 3.5
(d) 3 √3

A

Question. The density of air at pressure of 105 Nm–2 is 1.2 kg m–3.
Under these conditions, the root mean square velocity of the air molecules in ms–1 is
(a) 500
(b) 1000
(c) 1500
(d) 3000

A

Question. An ideal gas is taken through a process in which the pressure and the volume are changed according to the equation P = kV. Molar heat capacity of the gas for the process is
(a) C =Cv+ R
(b) C =Cv+ R/2
(c) C =C– R/2
(d) C =Cv+ 2R

B

Question. A vessel has 6g of hydrogen at pressure P and temperature 500K. A small hole is made in it so that hydrogen leaks out. How much hydrogen leaks out if the final pressure is P/2 and temperature falls to 300 K ?
(a) 2g
(b) 3g
(c) 4g
(d) 1g

D

Question. The molar specific heat at constant pressure of an ideal gas is (7/2)R. The ratio of specific heat at constant pressure to that at constant volume is
(a) 5/7
(b) 9/7
(c) 7/5
(d) 8/7

C

Question. A vessel of volume V contains a mixture of 1 mole of hydrogen and 1 mole oxygen (both considered as ideal).
Let f1(v)dv, denote the fraction of molecules with speed between v and (v + dv ) with f2(v)dv, similarly for oxygen.
Then,
(a) f1(v) + f2 (v) = f (v) obeys the Maxwell’s distribution law
(b) f1(v), f2(v) will obey the Maxwell’s distribution law separately
(c) neither f1(v), nor f2(v) will obey the Maxwell’s distribution law
(d) f2(v) and f1(v) will be the same