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

 The compressibility factor for H₂ and He is usually:

1. >1                                     

2. =1

3. <1                                     

4. either of these

Boyle's law is applicable in :

1. Isobaric process

2. Isochoric process

3. Isothermal process

4. Adiabatic process

The temperature of the gas is raised from 27$°$C to 927$°$C the root mean square velocity is        

1. $\sqrt{\frac{927}{27}}$ times of the earlier value

2. same as before

3. halved

4. doubled

At lower temperature, all gases except H₂ and He show:

1. Negative deviation

2. Positive deviation

3. Positive and negative deviation

4. None of the above

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

A gas cannot be liquefied if:

1. Forces of attraction are low under ordinary conditions

2. Forces of attraction are high under ordinary conditions

3. Forces of attraction are zero under ordinary conditions

4. Forces of attraction are either high or low under ordinary conditions

In the case of hydrogen and helium the van der Waals' forces are-

1. Strong                 

2. Very strong

3. Weak                   

4. None of the above

With the increase of pressure, the mean free path:

1. decreases                             

2. increases

3. becomes zero                       

4. remains the same

The compressibility factor of an ideal gas is:

1. zero                         

2. infinite

3. 1                               

4. -1