The anhydride of `HClO_(4)` is

Options

A. `ClO_(2)`
B. `Cl_(2)O_(2)`
C. `Cl_(2)O_(7)`
D. None..

Explanation

To determine the anhydride of \( HClO_4 \), we need to analyze the oxidation states of chlorine in different compounds and find the one that corresponds to the anhydride of \( HClO_4 \).

### Step-by-Step Solution:

1. **Identify the Oxidation State of Chlorine in \( HClO_4 \)**:
- The formula for \( HClO_4 \) consists of one hydrogen (H), one chlorine (Cl), and four oxygen (O) atoms.
- The oxidation state of oxygen is typically -2. Therefore, for four oxygen atoms: \( 4 \times (-2) = -8 \).
- Let the oxidation state of chlorine be \( x \). The equation based on the overall charge of the molecule being zero is:
\[ +1 + x + (-8) = 0 \]
- Solving for \( x \):
\[ x - 7 = 0 \implies x = +7 \]
- Thus, the oxidation state of chlorine in \( HClO_4 \) is +7.

2. **Determine the Anhydride**:
- An anhydride of an acid is typically a compound formed by the removal of water from the acid.
- The anhydride of \( HClO_4 \) will have chlorine in the same oxidation state, which is +7.

3. **Evaluate the Given Options**:
- **Option A**: \( Cl_2O_2 \)
- Oxidation state calculation:
\[ 2x - 4 = 0 \implies 2x = 4 \implies x = +2 \]
- This does not match +7.

- **Option B**: \( Cl_2O_7 \)
- Oxidation state calculation:
\[ 2x - 14 = 0 \implies 2x = 14 \implies x = +7 \]
- This matches +7, indicating that \( Cl_2O_7 \) is the anhydride of \( HClO_4 \).

- **Option C**: \( ClO_3 \)
- Oxidation state calculation:
\[ x - 6 = 0 \implies x = +6 \]
- This does not match +7.

- **Option D**: \( ClO \)
- Oxidation state calculation:
\[ x - 2 = 0 \implies x = +2 \]
- This does not match +7.

4. **Conclusion**:
- The only compound that has chlorine in the +7 oxidation state and is the anhydride of \( HClO_4 \) is \( Cl_2O_7 \).

### Final Answer:
The anhydride of \( HClO_4 \) is \( Cl_2O_7 \).