A compound that gives a positive iodoform test is

Options

A. pentan-1-ol
B. pentane-3-one
C. pentane-2-one
D. pentanal

Answer

To determine which compound gives a positive iodoform test, we need to identify the presence of a methyl ketone group (–C(=O)CH3) in the given options. The iodoform test is a chemical reaction that indicates the presence of this specific functional group.

### Step-by-Step Solution:

1. **Understand the Iodoform Test**:
- The iodoform test is used to identify compounds that contain a methyl ketone group (–C(=O)CH3) or ethanol (ethyl alcohol) derivatives. The test involves the reaction of the compound with iodine (I2) in the presence of a base (NaOH), producing a yellow precipitate of iodoform (CHI3).

2. **Analyze the Given Options**:
- We will examine each option to see if it contains a methyl ketone group.

3. **Option 1: Pentan-1-ol**:
- Structure: CH3-CH2-CH2-CH2-OH
- Analysis: This compound is a primary alcohol and does not have a ketone group. Therefore, it cannot give a positive iodoform test.

4. **Option 2: Pentan-2-ol**:
- Structure: CH3-C(=O)-CH2-CH2-CH3
- Analysis: This compound has a methyl group adjacent to a carbonyl group (C=O). It is a secondary alcohol with a methyl ketone structure. Thus, it will give a positive iodoform test.

5. **Option 3: Pentanal**:
- Structure: CH3-CH2-CH2-CHO
- Analysis: This compound is an aldehyde and does not contain a methyl ketone group. Therefore, it will not give a positive iodoform test.

6. **Conclusion**:
- The only compound that gives a positive iodoform test is **Pentan-2-ol**.

### Final Answer:
**Pentan-2-ol** gives a positive iodoform test.