Which of the following gives white precipitate with ammoniacal `AgNO_3` solution?

Options

A. `C_2 H_4`
B. `C_2H_2`
C. `C_2H_6`
D. `CH_4`

Explanation

To determine which of the given hydrocarbons gives a white precipitate with ammoniacal AgNO3 solution, we need to analyze the acidic hydrogen present in each compound. The presence of acidic hydrogen is crucial because it reacts with silver nitrate to form a precipitate.

### Step-by-Step Solution:

1. **Identify the Compounds**:
Let's consider the hydrocarbons mentioned in the video transcript. The compounds are:
- C2H4 (Ethylene)
- C2H2 (Acetylene)
- C2H6 (Ethane)
- CH4 (Methane)

2. **Determine the Hybridization and S Character**:
- **C2H4 (Ethylene)**:
- Structure: CH2=CH2
- Hybridization: SP2
- S Character: 33%
- **C2H2 (Acetylene)**:
- Structure: HC≡CH
- Hybridization: SP
- S Character: 50%
- **C2H6 (Ethane)**:
- Structure: CH3-CH3
- Hybridization: SP3
- S Character: 25%
- **CH4 (Methane)**:
- Structure: CH4
- Hybridization: SP3
- S Character: 25%

3. **Assess the Acidity of Hydrogen**:
- The more S character a carbon has, the more acidic the hydrogen attached to it.
- Acetylene (C2H2) has the highest S character (50%), indicating it has the most acidic hydrogen.

4. **Reaction with Ammoniacal AgNO3**:
- Acetylene (C2H2) is known to react with ammoniacal AgNO3 to form a white precipitate of silver acetylide (Ag2C2).
- Other compounds (C2H4, C2H6, CH4) do not have sufficiently acidic hydrogens to react with AgNO3 in this manner.

5. **Conclusion**:
- Therefore, the compound that gives a white precipitate with ammoniacal AgNO3 solution is **C2H2 (Acetylene)**.

### Final Answer:
**C2H2 (Acetylene)** gives a white precipitate with ammoniacal AgNO3 solution.