Which two of the following reactions are possible?
(i) `FeCl_(3)+SnCl_(2)to2FeCl_(2)+SnCl_(4)`
(ii) `2FeCl_(2)+SnCl_(4)to2FeCl_(3)+SnCl_(2)`
(iii) `PbCl_(2)+SnCl_(4)toSnCl_(2)+PbCl_(4)`
(iv). `SnCl_(2)+PbCl_(4)toPbCl_(2)+SnCl_(4)`

Options

A. `i` and ii
B. `i` and iii
C. `i` and iv
D. ii and iv

Answer

To determine which two of the given reactions are possible, we will analyze each reaction based on the reduction potentials of the involved species.

### Step 1: Analyze Reaction (i)
**Reaction:** `FeCl3 + SnCl2 → 2FeCl2 + SnCl4`

- **Oxidation States:**
- Fe in FeCl3 is in +3 oxidation state and in FeCl2 is in +2 oxidation state.
- Sn in SnCl2 is in +2 oxidation state and in SnCl4 is in +4 oxidation state.

- **Reduction Potentials:**
- For Fe: \( \text{Fe}^{3+} + e^- \rightarrow \text{Fe}^{2+} \) has a reduction potential of +0.77 V.
- For Sn: \( \text{Sn}^{4+} + 2e^- \rightarrow \text{Sn}^{2+} \) has a reduction potential of +0.15 V.

- **Conclusion for Reaction (i):**
Since the reduction potential of Fe is higher than that of Sn, Fe will be reduced (from +3 to +2) and Sn will be oxidized (from +2 to +4). Therefore, this reaction is possible.

### Step 2: Analyze Reaction (ii)
**Reaction:** `2FeCl2 + SnCl4 → 2FeCl3 + SnCl2`

- **Oxidation States:**
- Fe in FeCl2 is in +2 oxidation state and in FeCl3 is in +3 oxidation state.
- Sn in SnCl4 is in +4 oxidation state and in SnCl2 is in +2 oxidation state.

- **Reduction Potentials:**
- For Fe: \( \text{Fe}^{2+} \rightarrow \text{Fe}^{3+} + e^- \) has a reduction potential of -0.77 V (reverse of the previous reaction).
- For Sn: \( \text{Sn}^{4+} + 2e^- \rightarrow \text{Sn}^{2+} \) has a reduction potential of +0.15 V.

- **Conclusion for Reaction (ii):**
Since the reduction potential of Sn is higher than that of Fe, Sn will be reduced (from +4 to +2) and Fe will be oxidized (from +2 to +3). Therefore, this reaction is not possible.

### Step 3: Analyze Reaction (iii)
**Reaction:** `PbCl2 + SnCl4 → SnCl2 + PbCl4`

- **Oxidation States:**
- Pb in PbCl2 is in +2 oxidation state and in PbCl4 is in +4 oxidation state.
- Sn in SnCl4 is in +4 oxidation state and in SnCl2 is in +2 oxidation state.

- **Reduction Potentials:**
- For Pb: \( \text{Pb}^{4+} + 2e^- \rightarrow \text{Pb}^{2+} \) has a reduction potential of +1.467 V.
- For Sn: \( \text{Sn}^{4+} + 2e^- \rightarrow \text{Sn}^{2+} \) has a reduction potential of +0.15 V.

- **Conclusion for Reaction (iii):**
Since the reduction potential of Pb is higher than that of Sn, Pb will be reduced (from +4 to +2) and Sn will be oxidized (from +4 to +2). Therefore, this reaction is not possible.

### Step 4: Analyze Reaction (iv)
**Reaction:** `SnCl2 + PbCl4 → PbCl2 + SnCl4`

- **Oxidation States:**
- Sn in SnCl2 is in +2 oxidation state and in SnCl4 is in +4 oxidation state.
- Pb in PbCl4 is in +4 oxidation state and in PbCl2 is in +2 oxidation state.

- **Reduction Potentials:**
- For Pb: \( \text{Pb}^{4+} + 2e^- \rightarrow \text{Pb}^{2+} \) has a reduction potential of +1.467 V.
- For Sn: \( \text{Sn}^{4+} + 2e^- \rightarrow \text{Sn}^{2+} \) has a reduction potential of +0.15 V.

- **Conclusion for Reaction (iv):**
Since the reduction potential of Pb is higher than that of Sn, Pb will be reduced (from +4 to +2) and Sn will be oxidized (from +2 to +4). Therefore, this reaction is possible.

### Final Conclusion
The two possible reactions are:
- Reaction (i): `FeCl3 + SnCl2 → 2FeCl2 + SnCl4`
- Reaction (iv): `SnCl2 + PbCl4 → PbCl2 + SnCl4`