The mean free path ($\mathrm{\lambda }$) of a gas sample is given by:

1. $\lambda =\sqrt{2}\pi {\sigma }^{2}N$                               

2. $\lambda =1/\sqrt{2}\pi {\sigma }^{2}N$

3. $\lambda =\sqrt{2}\pi \mu {\sigma }^{2}N$                               

4. none of these

The maximum deviation from ideal gas behaviour takes place -  

1. At high temperature and low pressure.

2. At low temperature and high pressure.

3. At high temperature and high pressure.

4. At low temperature and low pressure.

At STP, 0.50-mole H₂ gas and 1.0 mole He gas                                  

1. have equal average kinetic energies

2. have equal molecular speeds

3. occupy equal volumes

4. have equal effusion rates

With the increase of pressure, the mean free path:

1. decreases                             

2. increases

3. becomes zero                       

4. remains the same

Internal energy and pressure of a gas per unit volume are related as                       

1. p= $\frac{2}{3}$E                         

2. p = $\frac{3}{2}$E

3. p=$\frac{1}{2}$E                         

4. p = 2E