## Kinetic Theory Questions and Answers Part-25

1. A box contains a mixture of $H_{2}$ and He gases. Which of the following statements are corrects
a) The average translational kinetic energies of $H_{2}$ molecules and He atoms are same
b) The average energies of $H_{2}$ molecules and He atoms are same
c) H2 molecules have greater average energy than that of He atoms
d) Both a and c

Explanation: Both a and c

2. If temperature of gas increases from $27^{\circ} C$  to $927^{\circ} C$  the K.E. will be
a) Double
b) Half
c) One fourth
d) Four times

Explanation: If temperature of gas increases from $27^{\circ} C$  to $927^{\circ} C$  the K.E. will be Four times

3. 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

Explanation: 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 1 : 1

4. Energy of all molecules of a monoatomic gas having a volume V and pressure P is $\frac{3}{2}PV$  . The total translational kinetic energy of all molecules of a diatomic gas as the same volume and pressure is
a) $\frac{1}{2}PV$
b) $\frac{3}{2}PV$
c) $\frac{5}{2}PV$
d) 3PV

Explanation: $\frac{3}{2}PV$

5. On absolute temperature, the kinetic energy of the molecules
a) Becomes zero
b) Becomes maximum
c) Becomes minimum
d) Remains constant

Explanation: On absolute temperature, the kinetic energy of the molecules becomes zero

6. The temperature of a gas is $-68^{\circ} C$  . At what temperature will the average kinetic energy of its molecules be twice that of at $-68^{\circ} C$
a) $137^{\circ} C$
b) $127^{\circ} C$
c) $100^{\circ} C$
d) $105^{\circ} C$

Explanation: $137^{\circ} C$

7. The average kinetic energy of a helium atom at $30^{\circ} C$  is
a) Less than 1 eV
b) A few keV
c) 50-60 eV
d) 13.6 eV

Explanation: The average kinetic energy of a helium atom at $30^{\circ} C$  is less than 1 eV

8. Two gases are at absolute temperatures 300 K and 350 K respectively. Ratio of average kinetic energy of their molecules is
a) 7 : 6
b) 6 : 7
c) 36 : 49
d) 49 : 36

Explanation: Two gases are at absolute temperatures 300 K and 350 K respectively. Ratio of average kinetic energy of their molecules is 6 : 7

9. A gas mixture consists of molecules of type 1, 2 and 3, with molar masses $m_{1}>m_{2}>m_{3}$  . $V_{rms}$  and $\bar{K}$  are the r.m.s. speed and average kinetic energy of the gases. Which of the following is true
a) $\left(V_{rms}\right)_{1}<\left(V_{rms}\right)_{2}<\left(V_{rms}\right)_{3}$      and $\left(\bar{K}\right)_{1}=\left(\bar{K}\right)_{2}=\left(\bar{K}\right)_{3}$
b) $\left(V_{rms}\right)_{1}=\left(V_{rms}\right)_{2}=\left(V_{rms}\right)_{3}$      and $\left(\bar{K}\right)_{1}=\left(\bar{K}\right)_{2}>\left(\bar{K}\right)_{3}$
c) $\left(V_{rms}\right)_{1}>\left(V_{rms}\right)_{2}>\left(V_{rms}\right)_{3}$      and $\left(\bar{K}\right)_{1}<\left(\bar{K}\right)_{2}>\left(\bar{K}\right)_{3}$
d) $\left(V_{rms}\right)_{1}>\left(V_{rms}\right)_{2}>\left(V_{rms}\right)_{3}$      and $\left(\bar{K}\right)_{1}<\left(\bar{K}\right)_{2}<\left(\bar{K}\right)_{3}$

Explanation: $\left(V_{rms}\right)_{1}<\left(V_{rms}\right)_{2}<\left(V_{rms}\right)_{3}$      and $\left(\bar{K}\right)_{1}=\left(\bar{K}\right)_{2}=\left(\bar{K}\right)_{3}$