Which one of the following gives iodoform test?

Options

A. Benzyl alcohol
B. Ethanol
C. Benzaldehyde
D. Formaldehyde

Answer

To determine which compound gives the iodoform test, we need to identify the functional groups present in the given options. The iodoform test is specifically positive for compounds that contain a methyl ketone group (R-CO-CH3) or certain secondary alcohols that can be oxidized to form such a group.

### Step-by-Step Solution:

1. **Understand the Iodoform Test**:
- The iodoform test is used to identify the presence of methyl ketones or secondary alcohols that can be oxidized to methyl ketones. The reaction involves iodine and sodium hydroxide.

2. **Identify the Functional Groups**:
- Review the options provided to identify which compounds have the methyl ketone functional group or can be oxidized to form one.

3. **Evaluate Each Compound**:
- **Option 1: Benzyl Alcohol (C6H5-CH2OH)**:
- This is a primary alcohol and does not contain a methyl ketone group. Therefore, it cannot give a positive iodoform test.
- **Option 2: Ethanol (CH3-CH2OH)**:
- Ethanol is a secondary alcohol that can be oxidized to acetaldehyde (which contains a methyl ketone group). Thus, it can give a positive iodoform test.
- **Option 3: Benzaldehyde (C6H5CHO)**:
- This is an aldehyde but not acetaldehyde. Only acetaldehyde can give a positive iodoform test among aldehydes. Therefore, this option is incorrect.
- **Option 4: Formaldehyde (HCHO)**:
- This is also an aldehyde and does not have the methyl ketone structure. Hence, it cannot give a positive iodoform test.

4. **Conclusion**:
- After evaluating all options, the only compound that can give a positive iodoform test is **Ethanol (Option 2)**.

### Final Answer:
**Ethanol (Option 2) gives a positive iodoform test.**