Of the following, the largest value of entropy at 25°C and 1 atm is that of:

At a given temperature, Entropy is highest for a gas with highest molar mass. Entropy is an extensive property. It depends on the quantity of substance.∴     Entropy at 250C and 1 atm is highest for C2H6C2H6  >   C2H2  > CH4  >  H2. Greater the atomicity of the gas ,greater the degrees of freedom hence higher the entropy