Which of the following are correctly matched?

Options

A. `HClOltHClO_(2) lt HClO_(3) lt HClO_(4)to`Thermal stability
B. `HClO lt HClO_(2) lt HClO_(3) lt HClO_(4)to` Acid strength.
C. `HClO lt HClO_(2) lt HClO_(3) lt HClO_(4) to` Oxidising power
D. `Hl lt HCl lt HBr lt H-F to` Acidic strength

Answer

To determine which of the following pairs are correctly matched, we need to analyze the thermal stability, acidic strength, and oxidizing power of the given compounds. The compounds in question are HClO, HClO2, HClO3, and HClO4, as well as the acids HI, HCl, HBr, and HF.

### Step-by-Step Solution:

1. **Determine the Oxidation States of Chlorine:**
- For HClO:
\[ +1 + x + (-2) = 0 \implies x = +1 \]
- For HClO2:
\[ +1 + x + 2(-2) = 0 \implies x = +3 \]
- For HClO3:
\[ +1 + x + 3(-2) = 0 \implies x = +5 \]
- For HClO4:
\[ +1 + x + 4(-2) = 0 \implies x = +7 \]

2. **Arrange the Compounds by Oxidation Number:**
- The oxidation states of chlorine in the compounds are:
- HClO: +1
- HClO2: +3
- HClO3: +5
- HClO4: +7
- Therefore, the order of increasing oxidation number is:
\[ \text{HClO} < \text{HClO2} < \text{HClO3} < \text{HClO4} \]

3. **Determine Thermal Stability:**
- Thermal stability is directly proportional to the oxidation state. Thus, the order of thermal stability is:
\[ \text{HClO4} > \text{HClO3} > \text{HClO2} > \text{HClO} \]

4. **Determine Acidic Strength:**
- Acidic strength is also directly proportional to oxidation number. Therefore, the order of acidic strength is:
\[ \text{HClO4} > \text{HClO3} > \text{HClO2} > \text{HClO} \]

5. **Determine Oxidizing Power:**
- Oxidizing power is inversely proportional to oxidation number. Thus, the order of oxidizing power is:
\[ \text{HClO} > \text{HClO2} > \text{HClO3} > \text{HClO4} \]

6. **Analyze the Halogen Acids (HI, HCl, HBr, HF):**
- As we move down the group in halogens, acidic strength increases due to decreasing electronegativity and increasing size. The order of acidic strength is:
\[ \text{HF} < \text{HCl} < \text{HBr} < \text{HI} \]

### Summary of Correct Matches:
- **Thermal Stability Order**: HClO4 > HClO3 > HClO2 > HClO (Correct)
- **Acidic Strength Order**: HClO4 > HClO3 > HClO2 > HClO (Correct)
- **Oxidizing Power Order**: HClO < HClO2 < HClO3 < HClO4 (Incorrect, correct order is HClO > HClO2 > HClO3 > HClO4)
- **Acidic Strength of HI, HCl, HBr, HF**: HI > HBr > HCl > HF (Incorrect, correct order is HF < HCl < HBr < HI)

### Final Answer:
The correctly matched pairs are:
- Thermal Stability
- Acidic Strength of HClO series