Which of the following ionic/molecular species does not disproportionate in water at room temperature?

Options

A. `NO_(2)`
B. `Cu^(+)`
C. `MnO_(4)^(2-)`
D. `Ca(OCl)Cl`

Explanation

To determine which of the given ionic/molecular species does not disproportionate in water at room temperature, we will analyze each species one by one.

### Step-by-Step Solution:

1. **Identify the Species**: The species given are:
- NO2 (Nitrogen dioxide)
- Cu⁺ (Copper(I) ion)
- MnO4²⁻ (Manganate ion)
- Ca(OCl)₂ (Calcium hypochlorite)

2. **Analyze NO2**:
- When NO2 is dissolved in water, it forms HNO3 (Nitric acid) and HNO2 (Nitrous acid).
- The oxidation states of nitrogen change from +4 in NO2 to +5 in HNO3 (oxidation) and +3 in HNO2 (reduction).
- Since the same species (NO2) undergoes both oxidation and reduction, this is a disproportionation reaction.

**Conclusion**: NO2 undergoes disproportionation.

3. **Analyze Cu⁺**:
- When Cu⁺ is dissolved in water, it can disproportionate to form Cu (Copper) and Cu²⁺ (Copper(II) ion).
- The oxidation states change from +1 in Cu⁺ to 0 in Cu (reduction) and +2 in Cu²⁺ (oxidation).
- This indicates that Cu⁺ also undergoes disproportionation.

**Conclusion**: Cu⁺ undergoes disproportionation.

4. **Analyze MnO4²⁻**:
- When MnO4²⁻ is dissolved in water, it can disproportionate to form MnO4⁻ (Permanganate ion), MnO2 (Manganese dioxide), and OH⁻ (Hydroxide ion).
- The oxidation states of manganese change from +6 in MnO4²⁻ to +7 in MnO4⁻ (oxidation) and +4 in MnO2 (reduction).
- This indicates that MnO4²⁻ also undergoes disproportionation.

**Conclusion**: MnO4²⁻ undergoes disproportionation.

5. **Analyze Ca(OCl)₂**:
- When Ca(OCl)₂ is dissolved in water, it dissociates into Ca²⁺, Cl⁻, and OCl⁻ ions.
- The oxidation states of chlorine in Cl⁻ and OCl⁻ remain the same (+1 for OCl⁻ and -1 for Cl⁻).
- Since there is no change in oxidation states, this does not represent a disproportionation reaction.

**Conclusion**: Ca(OCl)₂ does not undergo disproportionation.

### Final Answer:
The species that does not disproportionate in water at room temperature is **Ca(OCl)₂**.

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