Acidic hydrogen is present in

Options

A. ethyne
B. ethene
C. benzene
D. ethane

Answer

To determine which compound contains acidic hydrogen among Ethane, Ethene, Benzene, and Ethyne, we need to analyze the hybridization and the corresponding S character of each compound. The acidic hydrogen is directly proportional to the S character; the higher the S character, the more acidic the hydrogen.

### Step-by-Step Solution:

1. **Identify the Structures and Hybridization**:
- **Ethane (C2H6)**: The structure is CH3-CH3. The hybridization of carbon in ethane is sp³.
- **Ethene (C2H4)**: The structure is CH2=CH2. The hybridization of carbon in ethene is sp².
- **Benzene (C6H6)**: The structure is a cyclic compound with alternating double bonds. The hybridization of carbon in benzene is sp².
- **Ethyne (C2H2)**: The structure is HC≡CH. The hybridization of carbon in ethyne is sp.

2. **Calculate S Character**:
- **Ethane (sp³)**: 25% S character.
- **Ethene (sp²)**: 33.3% S character.
- **Benzene (sp²)**: 33.3% S character.
- **Ethyne (sp)**: 50% S character.

3. **Determine Acidity Based on S Character**:
- The acidic hydrogen is more prevalent in compounds with higher S character.
- Ethane has 25% S character, Ethene and Benzene have 33.3% S character, and Ethyne has 50% S character.

4. **Conclusion**:
- Since Ethyne has the highest S character (50%), it has the most acidic hydrogen. Therefore, the compound with the acidic hydrogen is **Ethyne**.

### Final Answer:
**Ethyne contains the acidic hydrogen.**