Compound (X) of molecular formula `C_4H_8` takes up one equivalent of hydrogen in presence of Pt to form another compound (Y),(X) on ozonolysis gives acetaldehyde as the only product. Compound (X) is

Options

A. `CH_3-CH_2-CH=CH_2`
B. `CH_3-CH=CH-CH_3`
C. Cyclobutane
D. Cyclobutene

Answer

To determine the compound (X) with the molecular formula \( C_4H_8 \) that takes up one equivalent of hydrogen in the presence of platinum to form another compound (Y), and on ozonolysis gives acetaldehyde as the only product, we can follow these steps:

### Step 1: Determine the Degree of Unsaturation
The degree of unsaturation can be calculated using the formula:
\[ \text{Degree of Unsaturation} = \frac{(2C + 2 + N - H - X)}{2} \]
Where:
- \( C \) = number of carbons
- \( H \) = number of hydrogens
- \( N \) = number of nitrogens
- \( X \) = number of halogens

For \( C_4H_8 \):
\[ \text{Degree of Unsaturation} = \frac{(2 \times 4 + 2 - 8)}{2} = \frac{(8 + 2 - 8)}{2} = \frac{2}{2} = 1 \]
This indicates that there is either one double bond or one ring in the structure.

### Step 2: Analyze the Reaction with Hydrogen
The compound (X) takes up one equivalent of hydrogen in the presence of platinum, indicating that (X) is likely an alkene. The reaction converts the alkene to an alkane.

### Step 3: Ozonolysis of Compound (X)
The ozonolysis of (X) gives acetaldehyde (CH₃CHO) as the only product. Ozonolysis typically cleaves double bonds to form carbonyl compounds. Since acetaldehyde is the only product, we need to consider the structure of (X) that can yield two acetaldehyde molecules upon cleavage.

### Step 4: Identify Possible Structures
Given the molecular formula \( C_4H_8 \) and the requirement that ozonolysis yields acetaldehyde, we can consider the following structure:
- 3-Butene (CH₃-CH=CH-CH₃)

When ozonolysis occurs on 3-butene, it breaks the double bond and forms two molecules of acetaldehyde:
\[ \text{Ozonolysis of } CH_3-CH=CH-CH_3 \rightarrow 2 \times CH_3CHO \]

### Step 5: Verify with Other Options
We can analyze other potential structures:
1. **1-Butene**: Ozonolysis would yield propanal and formaldehyde, not acetaldehyde.
2. **Cyclobutene**: Ozonolysis would yield products that do not include acetaldehyde.
3. **2-Butene**: Ozonolysis would yield acetaldehyde and another product, but we need only acetaldehyde.

### Conclusion
The compound (X) that meets all the criteria is **2-butene** (CH₃-CH=CH-CH₃).

### Final Answer
**Compound (X) is 2-butene.**