The number of electrons involve in the equation `CrO_4^(2-)rarrCr_2O_7^(2-)` Then value of x is equal to

Options

A. 0
B. 1
C. 3
D. 5

Answer

To solve the problem of determining the number of electrons involved in the reaction \( \text{CrO}_4^{2-} \rightarrow \text{Cr}_2\text{O}_7^{2-} \), we need to analyze the oxidation states of chromium in both species.

### Step-by-Step Solution:

1. **Identify the oxidation state of chromium in \( \text{CrO}_4^{2-} \)**:
- The formula for the oxidation state can be set up as follows:
\[ x + 4(-2) = -2 \]
- Here, \( x \) is the oxidation state of chromium, and there are 4 oxygen atoms each with an oxidation state of -2.
- Simplifying this gives:
\[ x - 8 = -2 \implies x = +6 \]

2. **Identify the oxidation state of chromium in \( \text{Cr}_2\text{O}_7^{2-} \)**:
- For \( \text{Cr}_2\text{O}_7^{2-} \), we set up the equation:
\[ 2x + 7(-2) = -2 \]
- Again, \( x \) is the oxidation state of chromium, and there are 7 oxygen atoms.
- Simplifying this gives:
\[ 2x - 14 = -2 \implies 2x = 12 \implies x = +6 \]

3. **Compare the oxidation states**:
- In both \( \text{CrO}_4^{2-} \) and \( \text{Cr}_2\text{O}_7^{2-} \), the oxidation state of chromium is +6.
- Since the oxidation state does not change, there is no transfer of electrons.

4. **Determine the number of electrons involved**:
- Since there is no change in the oxidation state of chromium, the number of electrons involved in the reaction is 0.

### Conclusion:
Thus, the value of \( x \) (the number of electrons involved) is equal to **0**.