Choose the redox reaction from the following -

Options

A. `Cu+2H_(2)SO_(4)rarrCuSO_(4)+SO_(2)+2H_(2)O`
B. `BaCl_(2)+H_(2)SO_(4)rarrBaSO_(4)+2HCl`
C. `Zn+H_(2)SO_(4)rarrZnSO_(4)+H_(2)`
D. `KNO_(3)+H_(2)SO_(4)rarr2HNO_(3)+K_(2)SO_(4)`

Answer

To determine which reactions are redox reactions from the given options, we will analyze each reaction by calculating the oxidation states of the elements involved. A redox reaction involves both oxidation (loss of electrons) and reduction (gain of electrons).

### Step-by-Step Solution:

1. **Understand Redox Reactions:**
- A redox reaction is one where both oxidation and reduction occur simultaneously. Oxidation is the increase in oxidation state (loss of electrons), while reduction is the decrease in oxidation state (gain of electrons).

2. **Analyze Reaction A:**
- **Reaction:** Cu + 2 H2SO4 → CuSO4 + SO2 + 2 H2O
- **Oxidation States:**
- Cu: 0 (reactant) → +2 (in CuSO4)
- H: +1 (in H2SO4) → +1 (in H2O)
- S: +6 (in H2SO4) → +4 (in SO2)
- O: -2 (remains -2)
- **Conclusion:** Cu is oxidized (0 to +2), and S is reduced (+6 to +4). This is a redox reaction.

3. **Analyze Reaction B:**
- **Reaction:** BaCl2 + H2SO4 → BaSO4 + 2 HCl
- **Oxidation States:**
- Ba: +2 (remains +2)
- Cl: -1 (remains -1)
- H: +1 (remains +1)
- S: +6 (remains +6)
- O: -2 (remains -2)
- **Conclusion:** No change in oxidation states. This is not a redox reaction.

4. **Analyze Reaction C:**
- **Reaction:** Zn + H2SO4 → ZnSO4 + H2
- **Oxidation States:**
- Zn: 0 (reactant) → +2 (in ZnSO4)
- H: +1 (in H2SO4) → 0 (in H2)
- S: +6 (remains +6)
- O: -2 (remains -2)
- **Conclusion:** Zn is oxidized (0 to +2), and H is reduced (+1 to 0). This is a redox reaction.

5. **Analyze Reaction D:**
- **Reaction:** KNO3 + H2SO4 → 2 HNO3 + K2SO4
- **Oxidation States:**
- K: +1 (remains +1)
- N: +5 (remains +5)
- O: -2 (remains -2)
- H: +1 (remains +1)
- S: +6 (remains +6)
- **Conclusion:** No change in oxidation states. This is not a redox reaction.

### Final Answer:
The reactions that are redox reactions are **Reaction A** and **Reaction C**.

---