Calculate the oxidation numbers of `Cr` in `K_(3)CrO_(8)`:

Options

A. `+6`
B. `+5`
C. `+3`
D. `+2`

Answer

To calculate the oxidation number of chromium (Cr) in potassium chromate (K₃CrO₈), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Compound**: The compound is K₃CrO₈. It contains potassium (K), chromium (Cr), and oxygen (O).

2. **Assign Known Oxidation States**:
- The oxidation state of potassium (K) is +1.
- The oxidation state of oxygen (O) in peroxides is -1. Since K₃CrO₈ contains peroxides, we will use -1 for oxygen.

3. **Set Up the Equation**:
- The overall charge of the compound is neutral (0).
- The formula for the oxidation states can be set up as follows:
\[ 3 \times (+1) + x + 8 \times (-1) = 0 \]
- Here, \( x \) represents the oxidation state of chromium (Cr).

4. **Calculate the Contributions**:
- Calculate the contribution from potassium:
\[ 3 \times (+1) = +3 \]
- Calculate the contribution from oxygen:
\[ 8 \times (-1) = -8 \]

5. **Combine the Contributions**:
- Substitute the contributions into the equation:
\[ +3 + x - 8 = 0 \]

6. **Solve for x**:
- Rearranging the equation gives:
\[ x - 5 = 0 \]
- Therefore, solving for \( x \):
\[ x = +5 \]

7. **Conclusion**:
- The oxidation number of chromium (Cr) in K₃CrO₈ is +5.