`S- S` bond is not present in

Options

A. Pyro sulphurous acid
B. Dithionic acid
C. Dithionous acid
D. Pyro sulphuric acid

Answer

To determine where the S-S bond is not present among the given compounds, we will analyze the structures and bonding of each compound step by step.

### Step 1: Identify the Compounds
The compounds given in the question are:
1. Pyrosulfurous acid (H₂S₂O₅)
2. Diethinic acid (H₂S₂O₆)
3. Diethinous acid (H₂S₂O₄)
4. Pyrosulfuric acid (H₂S₂O₇)

### Step 2: Analyze the Structures
We need to analyze the structures of each compound to see if they contain an S-S bond.

- **Pyrosulfurous acid (H₂S₂O₅)**: The structure has an S-O-S linkage. Each sulfur atom is connected to one double-bonded oxygen and one hydroxyl (OH) group. There is no S-S bond present.

- **Diethinic acid (H₂S₂O₆)**: This compound has an S-S linkage. Each sulfur atom is connected to two double-bonded oxygens and one hydroxyl (OH) group. Therefore, it contains an S-S bond.

- **Diethinous acid (H₂S₂O₄)**: Similar to diethinic acid, this compound also has an S-S linkage. Each sulfur atom is connected to one double-bonded oxygen and one hydroxyl (OH) group. Thus, it contains an S-S bond.

- **Pyrosulfuric acid (H₂S₂O₇)**: This compound has an S-O-S linkage. Each sulfur atom is connected to two double-bonded oxygens and one hydroxyl (OH) group. There is no S-S bond present.

### Step 3: Conclusion
From the analysis, we can conclude:
- The S-S bond is **not present** in:
- Pyrosulfurous acid (H₂S₂O₅)
- Pyrosulfuric acid (H₂S₂O₇)

Thus, the correct answer is that the S-S bond is not present in **pyrosulfurous acid and pyrosulfuric acid**.

### Final Answer
The S-S bond is not present in **pyrosulfurous acid (H₂S₂O₅)** and **pyrosulfuric acid (H₂S₂O₇)**.

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