Which aqueous solution should form a precipitate with aqueous cu (no3) 2? 1. kno3 2. cuso4 3. k2so4 4. k2s?

Reaction of Cu (NO₃) ₂ with each salt is as follow,

1) with KNO₃;

Cu (NO₃) ₂ + KNO₃ → Cu (NO₃) ₂ + KNO₃

Both salt products are water soluble.

2) With CuSO₄;

Cu (NO₃) ₂ + CuSO₄ → CuSO₄ + Cu (NO₃) ₂

Again both Salt products are water soluble.

3) With K₂SO₄;

Cu (NO₃) ₂ + K₂SO₄ → CuSO₄ + 2 KNO₃

Again both salt products are water soluble.

4) With K₂S;

Cu (NO₃) ₂ + K₂S → CuS + 2 KNO₃

In this case CuS is water insoluble, hence precipitates out.

Result:

Option-4 is the correct answer.