For an ideal solution , the correct option is : 

Question : For an ideal solution, the correct option is :

(1) Δmix S = 0 at constant T and P

(2) Δmix V  0 at constant T and P

(3) Δmix H = 0 at constant T and P 

(4) Δmix G = 0 at constant T and P

Answer : from all above options the correct answer is “(3) Δmix H = 0 at constant T and P ” first of all you must know that ideal solution must obey the rule of Raoult on all concentration and temperature conditions. for a ideal solution the Δmix H must be zero at a constant temperature and pressure . that is why we have marked option (3) for correct answer.

Answer explanation : The conditions of ideal solution are as follows :

if we talk about the definition of ideal solution then you must write that the solution which contains similar interactions between solute-solvent (A-B) , if the solvent consists (A-A) interactions  and solute particles consists (B-B) interactions  then between solute-solvent interactions will be found (A-B), these types of solution is called ideal solution , and ideal solution fulfill the condition of it’s equation which is given above.