The compound most likely to decolourize a solution of potassium permanganate is

Options

A. `CH_3CH_3`
B.
C. `CH_3CH=CHCH_2CH_3`
D. `CH_3-undersetunderset(CH_3)|oversetoverset(CH_3)|C-CH_3`

Explanation

To determine which compound is most likely to decolorize a solution of potassium permanganate (KMnO4), we need to understand the properties of the compounds involved and the nature of the reaction.

### Step-by-Step Solution:

1. **Understanding Potassium Permanganate**:
Potassium permanganate is a strong oxidizing agent. It is purple in color, and its color can be decolorized by certain organic compounds, particularly those that are unsaturated (i.e., contain double or triple bonds).

**Hint**: Remember that KMnO4 is purple and will lose its color when it reacts with certain compounds.

2. **Identifying Unsaturated Compounds**:
Unsaturated compounds contain double bonds (alkenes) or triple bonds (alkynes). These bonds can react with KMnO4, leading to the decolorization of the solution.

**Hint**: Look for compounds with double or triple bonds, as these are the ones that can react with KMnO4.

3. **Analyzing the Given Options**:
- **Option 1**: CH3-CH3 (Ethane) - This is a saturated hydrocarbon (only single bonds).
- **Option 2**: Benzene (C6H6) - While it has alternating double bonds, it does not readily react with KMnO4 to decolorize it due to its stable aromatic structure.
- **Option 3**: An alkene (e.g., CH2=CH2) - This compound has a double bond and is unsaturated, making it likely to react with KMnO4 and decolorize it.
- **Option 4**: CH3-CH2-CH3 (Propane) - This is also a saturated hydrocarbon (only single bonds).

**Hint**: Compare the structures of each option to identify which has double or triple bonds.

4. **Conclusion**:
The compound that is most likely to decolorize a solution of potassium permanganate is the one with a double bond, which is found in **Option 3** (the alkene).

**Final Answer**: Option 3 (the alkene) is the correct answer.