Which of the following is NOT a disproportiation reaction?

Options

A. `3Cl_(2) + 6OH^(-)(aq) rarr 5Cl^(-)(aq) + ClO_(3)^(-)(aq) + 3H_(2)O(l)`
B. `2KMnO_(4)(s) underset(("Heat"))overset(Delta)rarr K_(2)MnO_(4)(s) + MnO_(2)(s) + O_(2)(g)`
C. `3H_(3)PO_(2)(s) underset("(Heat)")overset(Delta)rarr 2H_(3)PO_(3)(s) + PH_(3)(g)`
D. `P_(4)(s) + 3OH^(-)(aq) + 3H_(2)O(l) overset(Delta)rarr PH_(3)(g) + 3H_(2)PO_(2)^(-1)(aq)`

Explanation

To determine which of the following reactions is NOT a disproportionation reaction, we first need to understand what a disproportionation reaction is. A disproportionation reaction is one in which a single element undergoes both oxidation and reduction simultaneously.

Let's analyze each option step by step:

### Step 1: Identify the reactions and their oxidation states

1. **Option 1: Cl2 → Cl⁻ + ClO3⁻**
- In Cl2, the oxidation state of Cl is 0.
- In Cl⁻, the oxidation state of Cl is -1.
- In ClO3⁻, the oxidation state of Cl can be calculated as follows:
- Let the oxidation state of Cl be x.
- The equation is: x + 3(-2) = -1 → x - 6 = -1 → x = +5.
- Here, Cl goes from 0 (in Cl2) to -1 (in Cl⁻) and +5 (in ClO3⁻).
- This shows both oxidation and reduction, so this is a disproportionation reaction.

2. **Option 2: KMnO4 → K2MnO4 + MnO2**
- In KMnO4, the oxidation state of Mn is +7.
- In K2MnO4, the oxidation state of Mn is +6.
- In MnO2, the oxidation state of Mn is +4.
- Here, Mn is reduced from +7 to +6 and +7 to +4, but there is no oxidation occurring.
- Therefore, this is NOT a disproportionation reaction.

3. **Option 3: H3PO2 → H3PO3 + PH3**
- In H3PO2, the oxidation state of P is +1.
- In H3PO3, the oxidation state of P is +3.
- In PH3, the oxidation state of P is -3.
- Here, P goes from +1 to +3 (oxidation) and +1 to -3 (reduction).
- This shows both oxidation and reduction, so this is a disproportionation reaction.

4. **Option 4: P4 → PH3 + H2PO2**
- In P4, the oxidation state of P is 0.
- In PH3, the oxidation state of P is -3.
- In H2PO2, the oxidation state of P can be calculated:
- Let the oxidation state of P be x.
- The equation is: 2(1) + x + 2(-2) = -1 → 2 + x - 4 = -1 → x - 2 = -1 → x = +1.
- Here, P goes from 0 to -3 (reduction) and from 0 to +1 (oxidation).
- This shows both oxidation and reduction, so this is a disproportionation reaction.

### Conclusion:
The reaction that is NOT a disproportionation reaction is **Option 2: KMnO4 → K2MnO4 + MnO2**.