Which of the following statements about the following reaction is`//`are not correct?
`Cr_(2)O_(7)^(2-)+3H_(2)O_(2)+8H^(o+)to2Cr^(3+)+7H_(2)O+3O_(2)`

Options

A. `H_(2)O_(2)` is oxidised to `O_(2)`
B. `H_(2)O_(2)` is reduced to `H_(2)O`
C. The oxidation number of chromium atom changes by `3`.
D. Hydrogen ions are oxidised to `H_(2)O`

Explanation

To determine which statements about the given reaction are not correct, we need to analyze the reaction step by step.

### Given Reaction:
\[ \text{Cr}_2\text{O}_7^{2-} + 3\text{H}_2\text{O}_2 + 8\text{H}^+ \rightarrow 2\text{Cr}^{3+} + 7\text{H}_2\text{O} + 3\text{O}_2 \]

### Step 1: Identify Oxidation States
- **Chromium in \(\text{Cr}_2\text{O}_7^{2-}\)**:
- Let the oxidation state of Cr be \(x\).
- The equation for the oxidation state is:
\[ 2x + 7(-2) = -2 \]
\[ 2x - 14 = -2 \]
\[ 2x = 12 \]
\[ x = +6 \]

- **Chromium in \(\text{Cr}^{3+}\)**:
- The oxidation state is +3.

### Step 2: Determine Change in Oxidation State
- The change in oxidation state of chromium:
- From +6 to +3, the change is:
\[ +6 - (+3) = +3 \]

### Step 3: Analyze Hydrogen Peroxide (\(\text{H}_2\text{O}_2\))
- **Oxidation of \(\text{H}_2\text{O}_2\)**:
- In the reaction, \(\text{H}_2\text{O}_2\) is oxidized to \(\text{O}_2\).

### Step 4: Analyze Hydrogen Ions (\(\text{H}^+\))
- **Reduction of \(\text{H}^+\)**:
- The hydrogen ions are not oxidized to \(\text{H}_2\text{O}\) in this reaction. Instead, they participate in the overall reaction to balance charges and contribute to the formation of water.

### Conclusion:
Based on the analysis:
1. **Statement A**: \(\text{H}_2\text{O}_2\) is oxidized to \(\text{O}_2\) - **True**
2. **Statement B**: \(\text{H}_2\text{O}_2\) is reduced to \(\text{H}_2\text{O}\) - **Not Correct**
3. **Statement C**: The oxidation number of chromium changes by 3 - **True**
4. **Statement D**: Hydrogen ions are oxidized to \(\text{H}_2\text{O}\) - **Not Correct**

### Final Answer:
The statements that are not correct are **B** and **D**.