What is the coordination entity formed when excess of aqueous KCN is added to an aqueous solution of copper sulphate? Why is it that no precipitate of copper sulphide is obtained when `H_(2)S` (g) is passed through this solution?

Explanation

To solve the problem, we need to break it down into two parts:

### Part 1: Coordination Entity Formation

1. **Identify the Reactants**:
- We start with an aqueous solution of copper sulfate, which contains Cu²⁺ ions and SO₄²⁻ ions.
- When excess aqueous KCN is added, it introduces CN⁻ ions into the solution.

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