A compound that gives a positive iodoform test is :

Options

A. 1-pentanol
B. 2-pentanone
C. 3-pentanone
D. pentanal

Explanation

To determine which compound gives a positive iodoform test, we need to follow these steps:

### 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 have a methyl group adjacent to the hydroxyl group (in the alpha position).

2. **Identify the Structure of Methyl Ketone**:
- A methyl ketone has the general structure of CH3C(=O)R, where R can be any alkyl group. The presence of the methyl group (CH3) adjacent to the carbonyl (C=O) is crucial for a positive test.

3. **Identify Compounds that Can Give a Positive Test**:
- **Aldehydes**: Only acetaldehyde (ethanal) can give a positive iodoform test.
- **Methyl Ketones**: Any methyl ketone will give a positive test.
- **Secondary Alcohols**: Secondary alcohols that have a methyl group in the alpha position will also give a positive test.

4. **Examine the Given Options**:
- Let's consider some common compounds:
- **Pentan-1-ol**: This is a primary alcohol and will not give a positive iodoform test.
- **2-Pentanone**: This is a methyl ketone (CH3C(=O)CH2CH2CH3) and will give a positive iodoform test.
- **3-Pentanone**: This is not a methyl ketone and will not give a positive test.
- **Ethanol**: This is a primary alcohol and will not give a positive test.

5. **Conclusion**:
- Among the compounds discussed, **2-Pentanone** is the one that gives a positive iodoform test due to its structure as a methyl ketone.

### Final Answer:
The compound that gives a positive iodoform test is **2-Pentanone**.