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

Joule-Thomson coefficient ($\partial \mathrm{T}/\partial \mathrm{P}$)_H for an ideal gas is:

1. zero                                 

2. +ve

3. -ve                                   

4. none of these

The beans are cooked in pressure cooker, because -                                   

1. Boiling point increases with increasing pressure

2. Boiling point decreases with increasing pressure

3. Extra pressure of pressure cooker softens the beans

4. Internal energy is not lost while cooking in pressure cooker

An ideal gas cannot be liquified because                                          

1. its critical temperature is always above 0$°$C

2. its molecules are relatively smaller in size

3. it solidifies before becoming a liquid

4. forces operating between its molecules are negligible

Boyle's law is applicable in :

1. Isobaric process

2. Isochoric process

3. Isothermal process

4. Adiabatic process

500 mL of nitrogen at 27$°$C are cooled to -5$°$C at the same pressure. The new volume becomes-      

1. 326.32 mL                     

2. 446.66 mL

3. 546.32 mL                     

4. 771.56 mL

With the increase of pressure, the mean free path:

1. decreases                             

2. increases

3. becomes zero                       

4. remains the same

The number of molecules present in 1 mL of gas or vapor at STP is:

1. called Loschmidt's number

2. equal to 2.617 x 10¹⁹ per mL

3. both (1) and (2)

4. none of the above

 Air at sea level is dense. This is a practical application of:

1. Boyle's law                         

2. Charles' law

3. Avogadro's law                   

4. Dalton's law

In van der Waals' equation of state of the gas, the constant 'b' is a measure of:

1. Intermolecular collisions per unit volume

2. Intermolecular attraction

3. Volume occupied by molecules

4. Intermolecular repulsions