How can you tell a cu(no3)2 solution from a ni(no3)2 solution?

solution has blue color and solution has bright green color.

Explanation:

in its aqueous solution gives blue color solution. Copper being transition metal and gives characteristic color in their in aqueous solution.

in its aqueous solution gives bright green color solution. Nickel is also a transition metal and gives characteristic color in their in aqueous solution.

c) should be the answer.