Consider a system of n atoms of an ideal gas of type a at temperature t and volume v. it is kept in diffusive contact with another system of n atoms of another

Consider a system of N atoms of an ideal gas of type A at temperature T and volume V. It is kept in diffusive contact with another system of N atoms of another ideal gas of type B at the same temperature T and volume V. Once the combined system reaches equilibrium, is (a) the total entropy of the final system is the same as the sum of the entropy of the individual system always (b) the entropy of mixing is 2Nkp ln 2 (c) the entropy of the final system is less than that of the sum of the initial entropies of the two gases. (d) the entropy of mixing is non-zero when the atoms A and B are of the same type.