Which of the following alkenes on ozonolysis gives a mixture of ketones only?

Options

A. `CH_(3)-CH=CH-CH_(3)`
B. `CH_(3)-underset(CH_(3))underset(|)(C)-CH=CH_(2)`
C.
D. `H_(2)C=CH_(2)`

Answer

To solve the question of which alkene on ozonolysis gives a mixture of ketones only, we will follow these steps:

### Step 1: Understand Ozonolysis
Ozonolysis is a reaction where alkenes react with ozone (O3) to form carbonyl compounds. The reaction typically proceeds through the formation of a cyclic ozonide intermediate, which then breaks down to yield aldehydes or ketones depending on the structure of the alkene.

**Hint:** Remember that the products of ozonolysis depend on the substitution pattern of the alkene.

### Step 2: Identify the Alkene Structures
We need to analyze the given alkenes. Let’s denote the alkenes as A, B, C, and D. We will examine each alkene to determine the products formed upon ozonolysis.

**Hint:** Look for the number of carbon atoms and the nature of substituents in each alkene.

### Step 3: Analyze Each Alkene
1. **Alkene A:**
- Structure: CH2=CH2 (Ethylene)
- Ozonolysis Products: This will yield two molecules of formaldehyde (HCHO), which are aldehydes.

2. **Alkene B:**
- Structure: CH3-CH=CH2 (Propene)
- Ozonolysis Products: This will yield one molecule of acetaldehyde (CH3CHO) and one molecule of formaldehyde (HCHO), both of which are aldehydes.

3. **Alkene C:**
- Structure: CH3-CH=CH-CH3 (Butene)
- Ozonolysis Products: This will yield two molecules of acetone (CH3COCH3), which are ketones.

4. **Alkene D:**
- Structure: CH3-CH2=CH2 (1-Butene)
- Ozonolysis Products: This will yield one molecule of acetaldehyde (CH3CHO) and one molecule of formaldehyde (HCHO), both of which are aldehydes.

**Hint:** Pay attention to the position of double bonds and the substituents on the carbon chain.

### Step 4: Conclusion
From the analysis:
- Alkene A produces aldehydes.
- Alkene B produces aldehydes.
- Alkene C produces ketones.
- Alkene D produces aldehydes.

Thus, the alkene that gives a mixture of ketones only upon ozonolysis is **Alkene C**.

**Final Answer:** Alkene C is the correct option.