The acid strength of oxyacids of the same halogen increases with increase in oxidation state of the halogen

The correct order of acid strength of oxyacids is:
c) HClO4 > HClO3 > HClO2 > HClO

Explanation:

Acid strength refers to the ability of an acid to donate a proton (H+ ion) to a base. In the case of oxyacids, they contain oxygen and hydrogen atoms bonded to a central atom. The strength of an oxyacid depends on the number of oxygen atoms bonded to the central atom and their electronegativity.

Here is a detailed explanation of the given order:

1. HClO4 (perchloric acid):
- Perchloric acid has four oxygen atoms bonded to the central chlorine atom (Cl).
- The electronegativity of oxygen is higher than chlorine, which leads to a greater polarity in the O-H bond.
- This results in a stronger acid, as the oxygen atom can easily donate its proton.

2. HClO3 (chloric acid):
- Chloric acid has three oxygen atoms bonded to the central chlorine atom.
- Although it has one less oxygen atom compared to perchloric acid, it still exhibits strong acidity due to the electronegativity difference between oxygen and chlorine.

3. HClO2 (chlorous acid):
- Chlorous acid has two oxygen atoms bonded to the central chlorine atom.
- It is weaker than both perchloric acid and chloric acid. The presence of fewer oxygen atoms results in a weaker acid.

4. HClO (hypochlorous acid):
- Hypochlorous acid has only one oxygen atom bonded to the central chlorine atom.
- It is the weakest acid among the given options. With only one oxygen atom, it has the lowest acidity.

In summary, the correct order of acid strength of oxyacids is HClO4 > HClO3 > HClO2 > HClO. Acid strength increases with the number of oxygen atoms bonded to the central atom and the electronegativity difference between the oxygen and central atom.