Which of the following undergoes haloform reaction?
(i) `CH_(3)CH_(2)COCH_(2)CI` (ii) `C_(6)H_(5)COCH_(3)`
(iii) `C_(6)H_(5)COCHI_(2)` (iv) `CH_(3)CH_(2)COCCI_(3)`

Options

A. only (ii)
B. (ii) and (iv)
C. (i), (ii) and (iv)
D. all the four

Explanation

To determine which of the following compounds undergoes a haloform reaction, we need to identify if they contain a methyl ketone structure (RCOCH3) or a compound that can be converted into such a structure. The haloform reaction typically occurs with compounds that have the structure RCOCH3, resulting in the formation of haloforms (like chloroform, bromoform, etc.) when treated with halogens.

Let's analyze each option:

### Step 1: Analyze the first compound `CH3CH2COCH2Cl`
- This compound can be represented as a ketone (specifically, a secondary alcohol with a chlorine substituent).
- When treated with halogens, it can undergo halogenation to form a trihalo compound.
- This compound has a structure that can lead to the formation of a methyl ketone upon halogenation.
- **Conclusion:** This compound can undergo a haloform reaction.

### Step 2: Analyze the second compound `C6H5COCH3`
- This compound is a methyl ketone (specifically, acetophenone).
- It has the structure RCOCH3, which is known to undergo the haloform reaction.
- **Conclusion:** This compound can undergo a haloform reaction.

### Step 3: Analyze the third compound `C6H5COCH2`
- This compound is a ketone but not a methyl ketone since it has a CH2 group instead of CH3.
- When treated with halogens, it can form a trihalo compound, but it does not meet the criteria for a haloform reaction, as it does not have a methyl group directly attached to the carbonyl.
- **Conclusion:** This compound does not undergo a haloform reaction.

### Step 4: Analyze the fourth compound `CH3CH2COCl3`
- This compound has a carbonyl group with a trihalo substituent.
- The presence of the trihalo group indicates it can undergo a haloform reaction.
- **Conclusion:** This compound can undergo a haloform reaction.

### Final Conclusion:
Based on the analysis:
- Compounds (i), (ii), and (iv) undergo a haloform reaction.
- Compound (iii) does not undergo a haloform reaction.

### Answer:
The compounds that undergo haloform reactions are:
- (i) `CH3CH2COCH2Cl`
- (ii) `C6H5COCH3`
- (iv) `CH3CH2COCl3`