
The compressibility factor for a definite amount of van der Waal’s gas at and 100 atm is found to be 0.5. Assuming the volume of gas molecules negligible, the van der Waals’ constant 'a' for the gas is . Then the value of is (nearest integer)

Important Questions on States of Matter
A gas has a compressibility factor of and a molar volume of at a temperature of and pressure . If it shows ideal gas behaviour at the same temperature and pressure, the molar volume will be . The value of is _________
[Use: Gas constant, ]


Among the gases and , the gases that show only positive deviation from ideal behavior at all pressures in the graph are





.
This equation reduces to the perfect gas equation, When,


The isotherms of a gas are shown below :
Among the following,
(i) At , the gas cannot be liquefied
(ii) At point , liquid starts to appear at
(ii) is the highest temperature at which the gas can be liquefied
(iv) At point , a small increase in pressure condenses the whole system to a liquid
The correct statements are :

The variation of the compressibility factorwith pressure for some gases, are shown in the figure below. Identify the gases and .








[Given : " a " and " b " are standard parameters for van der Waals' gas]


