In chemical analysis, the presence of a methyl ketonic group is tested with `I_(2)` in presence of an alkali like NaOH or KOH. In another chemical analysis, aldehyde group is tested either by Tollens' reagent `(AgNO_(3)NH_(3)OH)` which gives silver mirror or by Fehling's solution `(CuSO_(4)+NaOH+` Roschelle salt) which gives red ppt. of copper (I) oxide.
Q. Consider the following compounds:
I. `CH_(3)-overset(O)overset(||)(C)-CH_(2)-overset(O)overset(||)(C)-CH_(3)`
II. `CH_(3)-overset(O)overset(||)(C)-overset(O)overset(||)(C)-CH_(3)`
III. `CH_(3)-overset(O)overset(||)(C)-OH`
IV. `CH_(3)-overset(O)overset(||)(C)-Cl`
Which will give iodoform test?

Options

A. Only I
B. Both I and II
C. Only II
D. All

Explanation

To determine which of the given compounds will give a positive iodoform test, we need to identify the presence of a methyl ketone group (–C(=O)–CH3) in the structures of the compounds. The iodoform test is specifically positive for compounds that contain a methyl ketone group or ethanol.

Let's analyze each compound step by step:

### Step 1: Analyze Compound I
**Compound I:** `CH3-C(=O)-CH2-C(=O)-CH3`

- This compound has two ketone groups. The first ketone group is attached to a methyl group (–C(=O)–CH3).
- Therefore, this compound contains a methyl ketone group.

**Conclusion:** Compound I will give a positive iodoform test.

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

- This compound has a ketone group (–C(=O)–) that is directly attached to two methyl groups (–C(=O)–CH3).
- Thus, it also contains a methyl ketone group.

**Conclusion:** Compound II will give a positive iodoform test.

### Step 3: Analyze Compound III
**Compound III:** `CH3-C(=O)-OH`

- This compound is a carboxylic acid (specifically acetic acid).
- It does not have a methyl ketone group.

**Conclusion:** Compound III will NOT give a positive iodoform test.

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

- This compound is an acyl chloride.
- It does not have a methyl ketone group.

**Conclusion:** Compound IV will NOT give a positive iodoform test.

### Final Conclusion
The compounds that will give a positive iodoform test are:
- Compound I
- Compound II

### Summary of Results:
- **Compound I:** Positive iodoform test
- **Compound II:** Positive iodoform test
- **Compound III:** Negative iodoform test
- **Compound IV:** Negative iodoform test