On catalytic reduction `(H_(2)//Pt)` how many alkenes will give n-butane ?

Options

A. 1
B. 2
C. 3
D. 4

Explanation

To determine how many alkenes can give n-butane upon catalytic reduction with hydrogen gas in the presence of platinum (H₂/Pt), we can analyze the possible alkenes that can be reduced to n-butane.

### Step-by-Step Solution:

1. **Identify the Structure of n-Butane**:
n-Butane (C₄H₁₀) is a straight-chain alkane with four carbon atoms. Its structural formula is CH₃-CH₂-CH₂-CH₃.

2. **Consider Alkenes that Can Be Reduced**:
We need to identify alkenes that can be converted into n-butane through catalytic hydrogenation. The following alkenes can be considered:
- 1-butene (CH₂=CH-CH₂-CH₃)
- cis-2-butene (cis-CH₃-CH=CH-CH₃)
- trans-2-butene (trans-CH₃-CH=CH-CH₃)

3. **Catalytic Reduction of 1-Butene**:
- When 1-butene undergoes catalytic reduction (H₂/Pt), it adds hydrogen across the double bond, resulting in n-butane.
- Reaction: CH₂=CH-CH₂-CH₃ + H₂ → CH₃-CH₂-CH₂-CH₃ (n-butane)

4. **Catalytic Reduction of cis-2-Butene**:
- When cis-2-butene is reduced, it also adds hydrogen across the double bond, leading to n-butane.
- Reaction: cis-CH₃-CH=CH-CH₃ + H₂ → CH₃-CH₂-CH₂-CH₃ (n-butane)

5. **Catalytic Reduction of trans-2-Butene**:
- Similarly, trans-2-butene undergoes catalytic reduction to yield n-butane.
- Reaction: trans-CH₃-CH=CH-CH₃ + H₂ → CH₃-CH₂-CH₂-CH₃ (n-butane)

6. **Count the Alkenes**:
- From the analysis, we find that 1-butene, cis-2-butene, and trans-2-butene can all be reduced to n-butane.
- Thus, there are a total of 3 alkenes that can produce n-butane upon catalytic reduction.

### Final Answer:
The total number of alkenes that give n-butane on catalytic reduction is **3**.