The unit of van der Waals' constant 'b' is :

1. cm³ mol^-1

2. litre mol^-1

3. m³ mol^-1

4. all of these 

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

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

 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