An orange coloured solution acidified with `H_2SO_4` and treated with
a substance `'X'` gives a blue coloured solution of `CrO_5`. The
substance `'X'` is

Options

A. `H_(2)O_(2)`
B. `H_(2)O`
C. `dil HCl`
D. `Conc HCl`

Explanation

To solve the question, we need to identify the substance 'X' that, when reacted with an orange-colored solution acidified with `H2SO4`, produces a blue-colored solution of `CrO5`. Let's break this down step by step.

### Step-by-Step Solution:

1. **Identify the Orange-Colored Solution**:
- The orange-colored solution mentioned in the question is likely potassium dichromate, `K2Cr2O7`. This compound is known for its distinct orange color.

2. **Reaction with `H2SO4`**:
- When potassium dichromate is treated with sulfuric acid (`H2SO4`), it forms chromic acid (`H2Cr2O7`) in an acidic medium. The reaction can be represented as:
\[ K2Cr2O7 + H2SO4 \rightarrow H2Cr2O7 + K2SO4 \]

3. **Identify the Substance 'X'**:
- The next step is to determine what substance 'X' could be that reacts with chromic acid to produce `CrO5`. The blue color of `CrO5` indicates that it is a product of the reaction involving hydrogen peroxide (`H2O2`).

4. **Reaction of Chromic Acid with Hydrogen Peroxide**:
- When chromic acid reacts with hydrogen peroxide, it produces chromium pentoxide (`CrO5`) and water. The balanced reaction is:
\[ H2Cr2O7 + 4H2O2 \rightarrow 2CrO5 + 5H2O \]
- This shows that hydrogen peroxide acts as a reducing agent, and it is indeed the substance 'X' we are looking for.

5. **Conclusion**:
- Therefore, the substance 'X' that gives a blue-colored solution of `CrO5` when reacted with the orange-colored solution (potassium dichromate) acidified with `H2SO4` is hydrogen peroxide (`H2O2`).

### Final Answer:
The substance 'X' is **Hydrogen Peroxide (H2O2)**.