For an ideal solution, the correct option is :-

Question

( A ) $\triangle_{mix} S = 0\; at \;constant \;T and P$
( B ) $\triangle_{mix} V\neq\; 0\; at \;constant \;T and P$
( C ) $\triangle_{mix}\; G = 0\; at\; constant\; T and P$
( D ) $\triangle_{mix} H = 0 \;at\;constant \;T and P$