The reactions that occurs at the cathode of a common dry cell is

Options

A. `2ZnO_(2)+Mn^(2+)+2e^(-)rarrMnZn_(2)O_(4)`
B. `MnrarrMn^(2+)+2e^(-)`
C. `2MnO_(2)+Zn^(2+)+2e^(-)rarrZnMn_(2)O_(4)`
D. `ZnrarrZSn^(2+)+2e^(-)`

Answer

To determine the reaction that occurs at the cathode of a common dry cell, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Components of a Common Dry Cell:**
- A common dry cell typically consists of zinc (Zn) as the anode and manganese dioxide (MnO2) as the cathode.

2. **Understand the Reactions in a Dry Cell:**
- In a dry cell, two main reactions occur: one at the anode and one at the cathode.
- The anode reaction involves the oxidation of zinc.

3. **Write the Anode Reaction:**
- The reaction at the anode can be represented as:
\[ \text{Zn} \rightarrow \text{Zn}^{2+} + 2e^- \]
- This shows that zinc loses two electrons and forms zinc ions.

4. **Write the Cathode Reaction:**
- The cathode reaction involves the reduction of manganese dioxide in the presence of zinc ions and electrons.
- The reaction can be represented as:
\[ 2\text{MnO}_2 + \text{Zn}^{2+} + 2e^- \rightarrow \text{ZnMn}_2\text{O}_4 \]
- This shows that manganese dioxide reacts with zinc ions and electrons to form zinc manganese oxide.

5. **Conclusion:**
- Therefore, the reaction that occurs at the cathode of a common dry cell is:
\[ 2\text{MnO}_2 + \text{Zn}^{2+} + 2e^- \rightarrow \text{ZnMn}_2\text{O}_4 \]
- Based on the options provided, the correct answer is option C.