An evacuated glass vessel weighs 40.0 g when empty, 135.0 g when filled with a liquid of density 0.95 g mL^$$-$$1 and 40.5 g when filled with an ideal gas at 0.82 atm at 250 K. The molar mass of the gas in g mol^$$-$$1 is :

(Given : R = 0.082 L atm K^$$-$$1 mol^$$-$$1)

Which one of the following is the correct PV vs P plot at constant temperature for an ideal gas? (P and V stand for pressure and volume of the gas respectively)

The unit of the van der Waals gas equation parameter 'a' in $$\left( {P + {{a{n^2}} \over {{V^2}}}} \right)(V - nb) = nRT$$ is :

The interaction energy of London forces between two particles is proportional to r^x, where r is the distance between the particles. The value of x is :