The treatment of an aqueous solution of 3.74 g of `Cu(NO_3)_2` with excess KI results in a brown solution along with the formation of a precipitate. Passing `H_2S` through this brown solution gives another precipitate X. The amount of X (in g) is ________.
[ given : atomic mass of `H=1 ,N=14 , O=16 , S=32 , K=39 ,Cu= 63 ,I=127]`