Cyanohydrin of the following compound on hydrolysis gives optically active product:

Options

A. HCHO
B. `CH_(3)CHO`
C. `CH_(3)COCH_(3)`
D. All the above

Answer

To solve the question regarding which cyanohydrin of the given compounds yields an optically active product upon hydrolysis, we need to analyze each compound step by step.

### Step-by-Step Solution:

1. **Identify the Compounds**: The question mentions that we need to analyze the cyanohydrin formation from three different compounds: formaldehyde (HCHO), acetaldehyde (CH3CHO), and acetone (CH3COCH3).

2. **Cyanohydrin Formation**:
- **Formaldehyde (HCHO)**:
- Reaction with HCN:
\[ HCHO + HCN \rightarrow H_2C(OH)(CN) \]
- Upon hydrolysis, this cyanohydrin yields:
\[ H_2C(OH)(CN) + H_2O \rightarrow HCOOH + NH_3 \]
- The product is formic acid (HCOOH), which is not optically active because it does not have a chiral center (two hydrogen atoms are identical).

- **Acetaldehyde (CH3CHO)**:
- Reaction with HCN:
\[ CH_3CHO + HCN \rightarrow CH_3C(OH)(CN) \]
- Upon hydrolysis, this cyanohydrin yields:
\[ CH_3C(OH)(CN) + H_2O \rightarrow CH_3COOH + NH_3 \]
- The product is lactic acid (CH3COOH), which is optically active because it has a chiral center (the carbon bearing the hydroxyl group has four different groups attached: CH3, OH, COOH, and H).

- **Acetone (CH3COCH3)**:
- Reaction with HCN:
\[ CH_3COCH_3 + HCN \rightarrow CH_3C(OH)(CN)CH_3 \]
- Upon hydrolysis, this cyanohydrin yields:
\[ CH_3C(OH)(CN)CH_3 + H_2O \rightarrow CH_3COOH + CH_3NH_2 \]
- The product is still not optically active because the carbon with the hydroxyl group is attached to two identical methyl groups (CH3), hence no chiral center is formed.

3. **Conclusion**:
- The only compound that produces an optically active product upon hydrolysis is **acetaldehyde (CH3CHO)**, which yields lactic acid.

### Final Answer:
The cyanohydrin of **acetaldehyde (CH3CHO)** on hydrolysis gives an optically active product.