Which of the following can give iodoform test?
(I) `CH_(3)-overset(O)overset(||)C-CH_(2)-overset(O)overset(||)C-CH_(3)`
(II) `C_(6)H_(5)-CH_(2)-overset(O)overset(||)C-CH_(3)`
(III) `CH_(3)-CHO`
(IV) `C_(6)H_(5)-overset(O)overset(||)C-CH_(3)`

Options

A. Only IV
B. II and IV
C. III and IV
D. All of these

Answer

To determine which of the given compounds can give the iodoform test, we need to identify if they contain a methyl ketone structure (i.e., a carbonyl group directly bonded to a methyl group, -CO-CH3). The iodoform test is positive for compounds that have this structure.

Let's analyze each compound step by step.

### Step 1: Analyze Compound I
**Compound I:** `CH₃-C(=O)-C(=O)-C(CH₃)-CH₃`

- This compound has a carbonyl group (C=O) and a methyl group (CH3) attached to it.
- Since it contains a methyl ketone structure, it can give a positive iodoform test.

**Conclusion:** Compound I can give the iodoform test.

### Step 2: Analyze Compound II
**Compound II:** `C₆H₅-CH₂-C(=O)-CH₃`

- This compound has a carbonyl group (C=O) and a methyl group (CH3) attached to it.
- It also contains a methyl ketone structure, so it can give a positive iodoform test.

**Conclusion:** Compound II can give the iodoform test.

### Step 3: Analyze Compound III
**Compound III:** `CH₃-CHO`

- This compound is an aldehyde with a carbonyl group (C=O) and a methyl group (CH3) attached to it.
- It fits the criteria for the iodoform test since it has a methyl group directly bonded to the carbonyl.

**Conclusion:** Compound III can give the iodoform test.

### Step 4: Analyze Compound IV
**Compound IV:** `C₆H₅-C(=O)-CH₃`

- This compound has a carbonyl group (C=O) and a methyl group (CH3) attached to it.
- It also contains a methyl ketone structure, so it can give a positive iodoform test.

**Conclusion:** Compound IV can give the iodoform test.

### Final Conclusion
All four compounds (I, II, III, and IV) can give the iodoform test because they all contain the necessary methyl ketone structure.