Which element will have the maximum oxidation number in `K_(2) Cr_(2) O_(7)` and `KMnO_(4)`-

Options

A. Mn
B. Cr
C. O
D. K

Answer

To determine which element has the maximum oxidation number in \( K_2Cr_2O_7 \) (potassium dichromate) and \( KMnO_4 \) (potassium permanganate), we will calculate the oxidation states of chromium and manganese in these compounds.

### Step 1: Analyze \( K_2Cr_2O_7 \)

1. **Identify the oxidation states of known elements**:
- Potassium (K) has an oxidation state of +1.
- Oxygen (O) has an oxidation state of -2.

2. **Set up the equation for chromium (Cr)**:
- Let the oxidation state of chromium be \( x \).
- There are 2 potassium atoms, contributing \( 2 \times +1 = +2 \).
- There are 7 oxygen atoms, contributing \( 7 \times -2 = -14 \).
- The overall charge of the compound is neutral (0).

3. **Write the equation**:
\[ 2(+1) + 2x + 7(-2) = 0 \]
Simplifying this gives:
\[ 2 + 2x - 14 = 0 \]
\[ 2x - 12 = 0 \]
\[ 2x = 12 \implies x = 6 \]

4. **Conclusion for \( K_2Cr_2O_7 \)**:
- The oxidation state of chromium in \( K_2Cr_2O_7 \) is +6.

### Step 2: Analyze \( KMnO_4 \)

1. **Identify the oxidation states of known elements**:
- Potassium (K) has an oxidation state of +1.
- Oxygen (O) has an oxidation state of -2.

2. **Set up the equation for manganese (Mn)**:
- Let the oxidation state of manganese be \( y \).
- There is 1 potassium atom, contributing \( +1 \).
- There are 4 oxygen atoms, contributing \( 4 \times -2 = -8 \).
- The overall charge of the compound is neutral (0).

3. **Write the equation**:
\[ +1 + y + 4(-2) = 0 \]
Simplifying this gives:
\[ 1 + y - 8 = 0 \]
\[ y - 7 = 0 \implies y = 7 \]

4. **Conclusion for \( KMnO_4 \)**:
- The oxidation state of manganese in \( KMnO_4 \) is +7.

### Final Comparison

- In \( K_2Cr_2O_7 \), the maximum oxidation state is +6 (for chromium).
- In \( KMnO_4 \), the maximum oxidation state is +7 (for manganese).

### Answer
The element with the maximum oxidation number is manganese in \( KMnO_4 \), which has an oxidation state of +7.

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