Class : XIth Subject : PHYSICS
Date : DPP No. : 2
Topic :- KINETIC THEORY
1. The adjoining figure shows graph of pressure and volume of a gas at two temperatures 𝑇1
and 𝑇2. Which of the following inferences is correct
P
T2
T1
V
a) 𝑇1 > 𝑇2 b) 𝑇1 = 𝑇2
c) 𝑇1 < 𝑇2 d)No interference can be drawn
2. At room temperature (27℃) the rms speed of the molecules of a certain diatomic gas is
found to be 1920 m𝑠-1. The gas is
a) Cl2 b) O2 c) N2 d) H2
3. At a given temperature, the pressure of an ideal gas of density 𝜌 is proportional to
1 1
a) 2 b) c) 𝜌2 d)𝜌
𝜌 𝜌
4. Temperature remaining constant, the pressure of gas is decreased by 20%. The
percentage change in volume
a) Increases by 20% b) Decreases by 20% c) Increases by 25% d) decreases by 25%
5. The rms velocity of gas molecules is 300 ms-1. The rms velocity of molecules of gas
with twice the molecular weight and half the absolute temperature is
a) 300 ms-1 b) 600 ms-1 c) 75 ms-1 d) 150 ms-1
6. A jar contains a gas and few drops of water at 𝑇 𝐾. The pressure in the jar is 830 𝑚𝑚 of
mercury. The temperature of jar is reduced by 1%. The saturated vapour pressure of water
at the two temperatures are 30 𝑚𝑚 and 25 𝑚𝑚 of mercury. Then the new pressure in the
jar will be
a) 917 𝑚𝑚 of 𝐻𝑔 b)717 𝑚𝑚 of 𝐻𝑔 c) 817 𝑚𝑚 of 𝐻𝑔 d)None of these
7. The gas equation
𝑃𝑉
= constant is true for a constant mass of an ideal gas undergoing
𝑇
a) Isothermal change b)Adiabatic change c) Isobaric change d)Any type of change
8. The pressure and temperature of two different gases is 𝑃 and 𝑇 having the volume 𝑉 for
each. They are mixed keeping the same volume and temperature, the pressure of the
mixture will be
a) 𝑃/2 b)𝑃 c) 2𝑃 d)4𝑃
9. Vessel 𝐴 is filled with hydrogen while vessel 𝐵, whose volume is twice that of 𝐴, is filled
with the same mass of oxygen at the same temperature. The ratio of the mean kinetic
energies of hydrogen and oxygen is
a) 16 :1 b)1 :8 c) 8 :1 d)1 :1
10. The root mean square speed of hydrogen molecules at 300 𝐾 is 1930 𝑚/𝑠. Then the root
mean square speed of oxygen molecules at 900 𝐾 will be
1930
a) 1930 3 𝑚/𝑠 b)836 𝑚/𝑠 c) 63 𝑚/𝑠 d) 𝑚/𝑠
3
11. A cylinder rolls without slipping down an inclined plane, the number of degrees of freedom
it has, is
a) 2 b)3 c) 5 d)1
12. Two spheres made of same material have radii in the ratio1 :2. Both are at same
temperature. Ratio of heat radiation energy emitted per second by them is
a) 1 : 2 b)1 : 4 c) 1 : 8 d)1 : 16
13. If 𝑟.𝑚.𝑠. velocity of a gas is 𝑉𝑟𝑚𝑠 = 1840 𝑚/𝑠 and its density 𝜌 = 8.99 × 10-2𝑘𝑔/𝑚3, the
pressure of the gas will be
a) 1.01 𝑁/𝑚2 b)1.01 × 103𝑁/𝑚2 c) 1.01 × 105𝑁/𝑚2 d)1.01 × 107𝑁/𝑚2
14. An ideal gas (γ = 1.5) is expanded adiabatically. How many times has the gas to be
expanded to reduce the root mean square velocity of molecules 2.0 times?
a) 4 times b) 16 times c) 8 times d) 2 times
15. The quantity of heat required to raise one mole through one degree kelvin for a
monoatomic gas at constant volume is
3 5 7
a) 𝑅 b) 𝑅 c) 𝑅 d)4𝑅
2 2 2
16. Calculate the ratio of rms speeds of oxygen gas molecules to that of hydrogen gas
molecules kept at the same temperature.
a) 1:4 b) 1:8 c) 1:2 d) 1:6
17. At constant pressure, the ratio of increase in volume of an ideal gas per degree rise in kelvin
temperature to it’s original volume is (𝑇 = absolute temperature of the gas)
a) 𝑇2 b)𝑇 c) 1/𝑇 d)1/𝑇2
18. Pressure versus temperature graphs of an ideal gas are as shown in figure. Choose the
wrong statement
P P P
T T T
(i) (ii) (iii)
a) Density of gas is increasing in graph (i) b)Density of gas is decreasing in graph (ii)
c) Density of gas is constant in graph (iii) d)None of these
19. A body takes 10 min to cool from 60℃ to 50℃. If the temperature of surroundings is 25℃
and 527℃ respectively. The ratio of energy radiated by 𝑃 and 𝑄 𝑖𝑠
a) 48℃ b)46℃ c) 49℃ d)42.85℃
20. A cylinder of radius 𝑟 and thermal conductivity 𝐾1 is surrounded by a cylindrical shell of
linear radius 𝑟 and outer radius2𝑟, whose thermal conductivity is 𝐾2. There is no loss of
heat across cylindrical surfaces, when the ends of the combined system are maintained at
temperatures 𝑇1 and 𝑇2. The effective thermal conductivity of the system, in the steady state
is
𝐾1𝐾2 𝐾 + 3𝐾2 3𝐾 + 𝐾2
a) b) 𝐾1 + 𝐾2 c) 1 d) 1
𝐾1 + 𝐾2 4 4
