Which of the following metal cation is reduced from its higher oxidation state `(+2)` to `(+1)` by both KI solution and excess of KCN solution?

Options

A. `Zn^(2+)`
B. `Hg^(2+)`
C. `Cu^(2+)`
D. None of these

Explanation

To solve the question of which metal cation is reduced from its higher oxidation state (+2) to (+1) by both KI solution and excess of KCN solution, we will analyze the options step by step.

### Step 1: Identify the metal cations
The metal cations we need to consider are Zinc (Zn), Mercury (Hg), and Copper (Cu).

### Step 2: Analyze Zinc (Zn)
- Zinc exists in the +2 oxidation state as Zn²⁺.
- When zinc reacts with KI, it forms ZnI₂, which is soluble in water.
- Since Zn remains in the +2 oxidation state and does not get reduced to +1, we can conclude that zinc is not the correct answer.

**Hint for Step 2:** Check the solubility of the compounds formed and whether the oxidation state changes.

### Step 3: Analyze Mercury (Hg)
- Mercury exists as Hg²⁺.
- When Hg²⁺ reacts with KI, it forms a red precipitate of HgI₂.
- Similar to zinc, mercury does not get reduced from +2 to +1 in this reaction, so mercury is also not the correct answer.

**Hint for Step 3:** Look for precipitate formation and determine if the oxidation state changes.

### Step 4: Analyze Copper (Cu)
- Copper exists in the +2 oxidation state as Cu²⁺.
- When Cu²⁺ reacts with KI, it forms CuI₂, which is unstable and quickly dissociates to form CuI and iodine (I₂).
- In this reaction, copper is reduced from +2 to +1 oxidation state (Cu⁺).

### Step 5: Reaction with KCN
- When Cu²⁺ reacts with excess KCN, it initially forms Cu(CN)₂, but this is unstable and decomposes.
- The final product is CuCN, which also indicates that copper is in the +1 oxidation state.

### Conclusion
Since copper is reduced from +2 to +1 in both reactions with KI and KCN, the correct answer is Copper (Cu).

**Final Answer:** Copper (Cu)