Which of following will show tautomerism :-

Options

A.
B.
C.
D. All of these

Answer

To determine which compounds show tautomerism, we need to analyze the presence of alpha-hydrogens in relation to the carbonyl functional group. Tautomerism typically occurs in compounds where there is an alpha-hydrogen adjacent to a carbonyl group, allowing for the migration of a hydrogen atom and the formation of an enol or keto form.

### Step-by-Step Solution:

1. **Identify the Functional Group**:
- The functional group we are focusing on in each option is the carbonyl group (C=O).

2. **Locate the Alpha-Carbon**:
- The alpha-carbon is the carbon atom directly adjacent to the carbonyl carbon.

3. **Check for Alpha-Hydrogens**:
- An alpha-hydrogen is a hydrogen atom attached to the alpha-carbon. We need to check each compound for the presence of at least one alpha-hydrogen.

4. **Analyze Each Option**:
- **Option A**: Check for alpha-hydrogens.
- The compound has alpha-hydrogens present. Therefore, it can show tautomerism.
- **Option B**: Check for alpha-hydrogens.
- This compound also has alpha-hydrogens present. Thus, it can show tautomerism.
- **Option C**: Check for alpha-hydrogens.
- This compound has one alpha-hydrogen present. Hence, it can also show tautomerism.

5. **Conclusion**:
- Since all three options (A, B, and C) have at least one alpha-hydrogen, they can all show tautomerism. Therefore, the answer is **D) All of the above**.