Most acidic hydrogen is present in

Options

A.
B.
C. `(CH_3CO)_3CH`
D. `(CH_3)_3COH`

Answer

To determine which compound has the most acidic hydrogen among the given options, we need to analyze the structures and the effects of substituents on the acidity of the hydrogen atoms.

### Step-by-Step Solution:

1. **Understanding Acidity**:
- The acidity of a hydrogen atom in a molecule is influenced by the stability of the conjugate base formed when that hydrogen is removed (deprotonation).
- Electron-withdrawing groups (EWGs) increase acidity by stabilizing the negative charge on the conjugate base, while electron-donating groups (EDGs) decrease acidity by destabilizing the conjugate base.

2. **Analyzing the First Compound**:
- The first compound has a carbonyl group (C=O) which is an electron-withdrawing group.
- The acidic hydrogen is adjacent to this carbonyl group, which increases its acidity due to the inductive effect.
- The presence of one carbonyl group suggests moderate acidity.

3. **Analyzing the Second Compound**:
- The second compound has two carbonyl groups.
- The acidic hydrogen here is also influenced by these two carbonyl groups, which will further increase the acidity compared to the first compound.
- However, the presence of additional alkyl groups may also introduce some electron-donating effects, but the overall effect is still an increase in acidity.

4. **Analyzing the Third Compound**:
- The third compound has three carbonyl groups.
- The presence of three carbonyl groups significantly enhances the acidity of the hydrogen due to increased electron-withdrawing effects.
- This compound is expected to have the highest acidity among the options due to the cumulative effect of the three carbonyl groups.

5. **Analyzing the Fourth Compound**:
- The fourth compound has an alcohol (-OH) group and three methyl groups.
- While the alcohol group is acidic, the three methyl groups are electron-donating and will decrease the acidity of the hydrogen attached to the alcohol.
- Therefore, this compound is likely to have the lowest acidity among the options.

6. **Conclusion**:
- Comparing the acidity of the hydrogens from all four compounds, the third compound with three carbonyl groups has the most acidic hydrogen due to the strong electron-withdrawing effect of multiple carbonyl groups.

### Final Answer:
The compound with the most acidic hydrogen is the **third compound**.