Alkenes on treating with `O_3` and then the product on reduction may give

Options

A. `CO_2` and water
B. aldehydes
C. ketones
D. none of the above

Answer

To solve the question regarding the treatment of alkenes with ozone (O₃) and the products obtained after reduction, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction**:
Alkenes react with ozone (O₃) in a process known as ozonolysis. This reaction involves the cleavage of the carbon-carbon double bond (C=C) and the formation of an ozonide intermediate.

2. **Consider a Terminal Alkene**:
For this example, let’s take a simple terminal alkene, such as propene (CH₃-CH=CH₂).

3. **Ozonolysis Reaction**:
When propene reacts with ozone, the double bond is cleaved, and an ozonide is formed. The reaction can be represented as:
\[ CH₃-CH=CH₂ + O₃ \rightarrow \text{ozonide} \]

4. **Formation of Ozonide**:
The ozonide is a cyclic compound that contains an oxygen-oxygen bond. For propene, the ozonide will have the structure:
\[ CH₃-CH(O)-O-CH₂ \]

5. **Reduction of Ozonide**:
The ozonide is then subjected to reduction, typically using zinc (Zn) in water (H₂O). This step breaks the ozonide and leads to the formation of carbonyl compounds.

6. **Products of Reduction**:
After reduction, the ozonide will yield:
- Acetone (CH₃-CO-CH₃), which is a ketone.
- Formaldehyde (HCHO), which is an aldehyde.

7. **Conclusion**:
Therefore, the products obtained from the ozonolysis of alkenes followed by reduction are aldehydes and ketones.

### Final Answer:
Alkenes on treating with O₃ and then the product on reduction may give **aldehydes and ketones**.