`H_(2)O_(2)` will oxidise

Options

A. `KMnO_(4)`
B. PbS
C. `MnO_(2)`
D. `H_(2)S`

Answer

To determine which substances can be oxidized by hydrogen peroxide (H₂O₂), we need to analyze the oxidation states of the elements involved in the reactions. Here’s a step-by-step solution:

### Step 1: Understand the Oxidation State of H₂O₂
- In hydrogen peroxide (H₂O₂), the oxidation state of oxygen is -1. This means that H₂O₂ can act as a reducing agent and can be oxidized itself to O₂ (where the oxidation state of oxygen is 0) or to water (H₂O, where the oxidation state of oxygen is -2).

### Step 2: Analyze the First Option: KMnO₄
- In potassium permanganate (KMnO₄), the oxidation state of manganese (Mn) is +7. Since Mn is in its highest oxidation state, it cannot be oxidized further. Therefore, H₂O₂ will not oxidize KMnO₄.

### Step 3: Analyze the Second Option: PbS
- In lead sulfide (PbS), the oxidation state of sulfur (S) is -2. When H₂O₂ reacts with PbS, it oxidizes sulfur from -2 to +6 (in PbSO₄). Thus, H₂O₂ oxidizes PbS.

### Step 4: Analyze the Third Option: MnO₂
- Manganese dioxide (MnO₂) is not oxidized by H₂O₂ as it acts as a catalyst in this reaction. H₂O₂ does not change the oxidation state of Mn in MnO₂.

### Step 5: Analyze the Fourth Option: H₂S
- In hydrogen sulfide (H₂S), the oxidation state of sulfur is -2. When H₂O₂ reacts with H₂S, it oxidizes sulfur from -2 to +6 (in H₂SO₄). Therefore, H₂O₂ oxidizes H₂S.

### Conclusion
- Based on the analysis, H₂O₂ can oxidize PbS and H₂S. Therefore, the correct options are PbS and H₂S.

### Final Answer
H₂O₂ will oxidize:
- **PbS (Lead Sulfide)**
- **H₂S (Hydrogen Sulfide)**