Alkenes undergo a variety of oxidation reactions. With cold and neutral or alkaline `KMnO_(4)`, alkenes are oxidised to give vicinal diols. Oxidation with hot `KMnO_(4)` undergoes cleavage of C=C bond leading to the formation of carboxylic acids, ketones and carbon dioxide depending on the nature ofalkene. Reductive ozonolysis of alkenes give aldehydes or ketones.
Reductive ozonolysis of alkene 'A' gives propanone. The alkene 'A' is

Options

A. 2,3,-Dimethylbut-2-ene
B. 1,4-Dimethylpent-2-ene
C. 1,3-Dimethylbut-2-ene
D. 2-Methylpropene

Explanation

To solve the problem of identifying the alkene 'A' that gives propanone upon reductive ozonolysis, we will analyze the provided options step by step.

### Step-by-Step Solution:

1. **Understanding Reductive Ozonolysis**:
Reductive ozonolysis of alkenes involves the cleavage of the C=C double bond, resulting in the formation of carbonyl compounds (aldehydes or ketones). The specific product formed depends on the structure of the alkene.

2. **Identifying Propanone**:
The molecular formula for propanone is \( \text{C}_3\text{H}_6\text{O} \) or \( \text{CH}_3\text{C}(=O)\text{CH}_3 \). We need to find an alkene that, when subjected to reductive ozonolysis, will yield this compound.

3. **Analyzing the Options**:
- **Option 1: 2,3-Dimethylbut-2-ene**
Structure:
\[ \text{CH}_3-\text{C}(\text{CH}_3)=\text{C}(\text{CH}_3)-\text{CH}_3 \]
When ozonolysis occurs, the double bond will break, leading to the formation of two propanone molecules. Thus, this option is likely correct.

- **Option 2: 1,4-Dimethylpent-2-ene**
Structure:
\[ \text{CH}_3-\text{C}(\text{CH}_3)=\text{C}-\text{C}(\text{CH}_3)-\text{CH}_3 \]
Ozonolysis will yield products that do not include propanone, so this option is incorrect.

- **Option 3: 1,3-Dimethylbut-2-ene**
Structure:
\[ \text{CH}_3-\text{C}(\text{CH}_3)=\text{C}-\text{CH}_2-\text{CH}_3 \]
Ozonolysis will yield products that do not include propanone, so this option is incorrect.

- **Option 4: 2-Methylpropene**
Structure:
\[ \text{CH}_3-\text{C}(\text{H})=\text{C}(\text{CH}_3)-\text{H} \]
Ozonolysis will yield formaldehyde and other products, but not propanone, making this option incorrect.

4. **Conclusion**:
After analyzing all options, **Option 1: 2,3-Dimethylbut-2-ene** is the only alkene that gives propanone upon reductive ozonolysis.

### Final Answer:
The alkene 'A' is **2,3-Dimethylbut-2-ene**.