a and b are van der Waals constants for gases. Chlorine is more easily liquefied than ethane because (KCET 2011)

The importance of the Van der Waals constants a and b is- The constant ‘a’ gives the measure of intermolecular forces of attraction. The constant b gives the measure of molecular size. If a > b then gas can liquefy easily. Therefore, chlorine is more easily liquefied than ethane because a value of chlorine is greater and b value of chlorine is less.