In which pair of ions both the species contains `S - S` bond?

Options

A. `S_(2)O_(7)^(2-), S_(2)O_(3)^(2-)`
B. `S_(4)O_(6)^(2-),S_(2)O_(3)^(2-)`
C. `S_(2)O_(7)^(2-),S_(2)O_(8)^(2-)`
D. `S_(4)O_(6)^(2-),S_(2)O_(7)^(2-)`.

Answer

To determine which pair of ions contains a sulfur-sulfur (S-S) bond, we will analyze the structures of the given species: S2O7^2-, S2O3^2-, S4O6^2-, and S2O8^2-.

### Step-by-Step Solution:

1. **Analyze S2O7^2-:**
- The structure consists of 2 sulfur atoms and 7 oxygen atoms.
- The arrangement includes double-bonded oxygens and negatively charged oxygens.
- There is an oxide bridge between the two sulfur atoms.
- **Conclusion:** There is no S-S bond in S2O7^2-.

2. **Analyze S2O3^2-:**
- This species has 2 sulfur atoms and 3 oxygen atoms.
- The structure shows one sulfur atom bonded to two oxygens and the other sulfur atom bonded to one oxygen.
- Importantly, there is a direct bond between the two sulfur atoms.
- **Conclusion:** There is an S-S bond in S2O3^2-.

3. **Analyze S4O6^2-:**
- This ion consists of 4 sulfur atoms and 6 oxygen atoms.
- The structure shows that the sulfur atoms are connected by single bonds.
- There are terminal sulfur atoms that are double-bonded to oxygen.
- **Conclusion:** There are S-S bonds present in S4O6^2-.

4. **Analyze S2O8^2-:**
- This species contains 2 sulfur atoms and 8 oxygen atoms.
- The structure shows double-bonded oxygens and a peroxide bond (O-O).
- There is no direct bond between the two sulfur atoms.
- **Conclusion:** There is no S-S bond in S2O8^2-.

### Final Conclusion:
The pair of ions that both contain a sulfur-sulfur bond is **S2O3^2- and S4O6^2-**.