`CrO_(4)^(2-)` (yellow) changes to `Cr_(2)O_(7)^(2-)(`orange ) in `pH=y` . Hence `x` and `y` are `:`

Options

A. `2.40`
B. `3.0`
C. `3.4771`
D. `4.0`

Explanation

To solve the problem, we need to analyze the conversion of the chromate ion \((CrO_4^{2-})\) to the dichromate ion \((Cr_2O_7^{2-})\) and determine the pH values \(x\) and \(y\) associated with this transformation.

### Step-by-Step Solution:

1. **Identify the Ions and Their Colors**:
- The chromate ion \((CrO_4^{2-})\) is yellow.
- The dichromate ion \((Cr_2O_7^{2-})\) is orange.

2. **Determine the Oxidation States**:
- In \((CrO_4^{2-})\), the oxidation state of chromium is +6.
- In \((Cr_2O_7^{2-})\), the oxidation state of chromium is +7.

3. **Analyze the Reaction**:
- The conversion from \((CrO_4^{2-})\) to \((Cr_2O_7^{2-})\) involves an increase in the oxidation state of chromium, indicating that oxidation is occurring.
- Oxidation typically requires an acidic environment.

4. **Determine the pH**:
- Since the reaction is an oxidation process, it is favored in acidic conditions. Therefore, the pH \(y\) must be less than 7.
- We can conclude that \(y\) is any value lower than 7.

5. **Assign Values to \(x\) and \(y\)**:
- Since the problem does not specify \(x\), we can assume \(x\) to be the oxidation state of chromium in \((CrO_4^{2-})\), which is +6.
- Thus, we can summarize:
- \(x = +6\)
- \(y < 7\) (for example, \(y = 6\) could be a valid choice).

### Final Answer:
- \(x = +6\) and \(y < 7\).