Most acidic hydrogen containing compound among the following is

Options

A.
B.
C.
D.

Answer

To determine which compound has the most acidic hydrogen among the given options, we need to analyze the acidity of each compound based on the stability of their conjugate bases and the effects of substituents on the hydroxyl (OH) group.

### Step-by-Step Solution:

1. **Understanding Acidity**:
- The acidity of a compound is determined by how easily it can donate a proton (H⁺). The more stable the conjugate base formed after the proton is removed, the stronger the acid.

2. **Identify the Compounds**:
- Let's assume the four compounds are derivatives of phenol with different substituents, particularly nitro (NO₂) groups at various positions (ortho, meta, and para).

3. **Effect of Substituents**:
- The presence of electron-withdrawing groups (like NO₂) increases the acidity of phenolic compounds by stabilizing the negative charge on the conjugate base (phenoxide ion) through resonance and inductive effects.

4. **Analyzing Each Compound**:
- **Compound 1**: NO₂ at ortho position. This position allows for strong resonance stabilization of the conjugate base.
- **Compound 2**: NO₂ at meta position. Here, the resonance effect is weaker, and only the inductive effect applies, which is less effective.
- **Compound 3**: NO₂ at para position. This position allows for resonance stabilization similar to the ortho position but is less effective than ortho due to distance.
- **Compound 4**: No NO₂ group. This compound will be the least acidic.

5. **Comparing Acidity**:
- The compound with the NO₂ group at the ortho position will have the most acidic hydrogen due to the combined effects of strong inductive and resonance effects.
- The compound with the NO₂ group at the meta position will be less acidic than the ortho and para compounds.
- The para compound will be more acidic than the meta compound but less than the ortho compound.

6. **Conclusion**:
- The compound with the NO₂ group at the ortho position has the most acidic hydrogen due to the maximum stabilization of the conjugate base.

### Final Answer:
The most acidic hydrogen containing compound among the given options is the one with the NO₂ group at the ortho position.