Which one of the following gives iodoform test?

Options

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

Answer

To determine which compound gives a positive iodoform test, we need to understand the conditions under which the iodoform test is positive. The iodoform test is typically positive for compounds that contain a methyl ketone group (R-CO-CH3) or for certain alcohols and aldehydes that can be oxidized to such ketones.

### Step-by-Step Solution:

1. **Understanding the Iodoform Test**:
- The iodoform test is used to identify methyl ketones or compounds that can be oxidized to methyl ketones. The test involves the reaction of the compound with iodine (I2) in the presence of sodium hydroxide (NaOH), leading to the formation of iodoform (CHI3), which precipitates as a yellow solid.

2. **Identifying the Required Structure**:
- For a compound to give a positive iodoform test, it must either be a methyl ketone (R-CO-CH3) or a secondary alcohol that can be oxidized to a methyl ketone.

3. **Analyzing the Options**:
- Let's evaluate the given options:
- **A. Benzyl Alcohol (C6H5CH2OH)**: This is a primary alcohol and does not have the methyl ketone structure. **Does not give a positive test.**
- **B. Acetaldehyde (CH3CHO)**: This is an aldehyde that can be oxidized to a methyl ketone. **Gives a positive test.**
- **C. Benzaldehyde (C6H5CHO)**: This is also an aldehyde but cannot be oxidized to a methyl ketone. **Does not give a positive test.**
- **D. Ethanol (CH3CH2OH)**: This is a primary alcohol that can be oxidized to acetaldehyde, which can then give a positive iodoform test. **Gives a positive test.**

4. **Conclusion**:
- Based on the analysis, **both Acetaldehyde and Ethanol** give a positive iodoform test. However, if the question is asking for a single answer, the most direct answer would be **B. Acetaldehyde**.

### Final Answer:
The compound that gives a positive iodoform test is **B. Acetaldehyde (CH3CHO)**.