The oxidising ability of perhalates are in the order:

Options

A. `CIO_(4)^(Theta) gt BrO_(4)^(Theta) gt IO_(4)^(Theta)`
B. `CIO_(4)^(Theta) lt BrO_(4)^(Theta) lt IO_(4)^(Theta)`
C. `BrO_(4)^(Theta) gt IO_(4)^(Theta) gt CIO_(4)^(Theta)`
D. `IO_(4)^(Theta) lt BrO_(4)^(Theta) lt CIO_(4)^(Theta)`

Answer

To determine the order of oxidizing ability of perhalates, we need to analyze the perhalate ions, which are of the form XO₄⁻, where X represents a halogen (Cl, Br, or I). The perhalates we are considering are ClO₄⁻ (perchlorate), BrO₄⁻ (perbromate), and IO₄⁻ (periodate).

### Step-by-Step Solution:

1. **Identify the Perhalates**:
The perhalates in question are:
- ClO₄⁻ (perchlorate)
- BrO₄⁻ (perbromate)
- IO₄⁻ (periodate)

2. **Understand Oxidizing Ability**:
The oxidizing ability of a compound is influenced by its electronegativity and oxidation state. Generally, a higher oxidation state and higher electronegativity contribute to stronger oxidizing properties.

3. **Determine Oxidation States**:
- For ClO₄⁻: Chlorine is in the +7 oxidation state.
- For BrO₄⁻: Bromine is in the +7 oxidation state.
- For IO₄⁻: Iodine is in the +7 oxidation state.
All three perhalates have the same oxidation state for their respective halogens.

4. **Consider Electronegativity**:
The electronegativity of the halogens decreases in the order: Cl > Br > I. This means that chlorine is the most electronegative, followed by bromine, and then iodine.

5. **Analyze the Oxidizing Ability Order**:
Since the oxidizing ability is directly proportional to electronegativity and all perhalates have the same oxidation state, we can conclude the order of oxidizing ability based on electronegativity:
- ClO₄⁻ (most oxidizing)
- BrO₄⁻
- IO₄⁻ (least oxidizing)

6. **Final Order**:
Therefore, the order of oxidizing ability of perhalates is:
- ClO₄⁻ > BrO₄⁻ > IO₄⁻

### Conclusion:
The correct order of the oxidizing ability of perhalates is ClO₄⁻ > BrO₄⁻ > IO₄⁻.