Which of the following represents the correct order of acidity?

Options

A. `HOClO lt HOCl lt HOClO_3 lt HOClO_2`
B. `HOClO_2 lt HOClO_3 lt HOClO lt HOCl`
C. `HOClO_3 lt HOClO_2 lt HOClO lt HOCl`
D. `HOCl lt HOClO lt HOClO_2 lt HOClO_3`

Answer

To determine the correct order of acidity among the given oxoacids of chlorine, we need to analyze the relationship between the oxidation state of the chlorine atom in these acids and their acidic strength.

### Step-by-Step Solution:

1. **Identify the Oxoacids**: The oxoacids in question are:
- HClO (Hypochlorous acid)
- HClO2 (Chlorous acid)
- HClO3 (Chloric acid)
- HClO4 (Perchloric acid)

2. **Determine the Oxidation States**:
- In HClO, the oxidation state of Cl is +1.
- In HClO2, the oxidation state of Cl is +3.
- In HClO3, the oxidation state of Cl is +5.
- In HClO4, the oxidation state of Cl is +7.

3. **Understand the Trend of Acidity**:
- The acidity of oxoacids generally increases with the increase in the oxidation state of the central atom (in this case, chlorine). This is because a higher oxidation state leads to a greater positive charge on the central atom, which stabilizes the conjugate base formed after the acid donates a proton (H+).

4. **Establish the Order of Acidity**:
- Based on the oxidation states, we can establish the following order of acidity:
- HClO4 (highest oxidation state, strongest acid)
- HClO3
- HClO2
- HClO (lowest oxidation state, weakest acid)

5. **Final Order of Acidity**:
- Therefore, the correct order of acidity is:
\[ \text{HClO4} > \text{HClO3} > \text{HClO2} > \text{HClO} \]

### Conclusion:
The correct answer is option 4, which states that:
\[ \text{HClO4} > \text{HClO3} > \text{HClO2} > \text{HClO} \]