`|{:(Column I,Column 2,Column 2),((I)"Toluene",(i)NaOH//Br_(2),(P)"Condensation"),((II)"Acetophenone",(ii)Br_(2)//hv,(Q)"Carboxylation"),((III)"Benzaldehyde",(iii)(CH_(3)CO)_(2)O //CH_(3)COOK,(R)"Substitution"),((IV)"Phenol",(iv)NaOH//CO_(2),(S)"Haloform"):}|`
The only correct combination in which the reaction proceeds through radical mechanism is

Options

A. (IV) (i) (Q)
B. (III) (ii) (P)
C. (II) (iii) (R )
D. (I) (ii) (R )

Explanation

To solve the problem, we need to analyze the reactions of the compounds listed in Column I with the reagents in Column II and identify the correct combinations that proceed through a radical mechanism.

### Step-by-Step Solution:

1. **Identify the Compounds and Reactions**:
- **Toluene (I)**: When treated with Br₂ and light (hv), toluene undergoes a free radical substitution reaction to form bromotoluene.
- **Acetophenone (II)**: Acetophenone reacts with NaOH and Br₂ in a haloform reaction, which does not proceed through a radical mechanism.
- **Benzaldehyde (III)**: Benzaldehyde can undergo a condensation reaction, specifically the Perkin reaction, which does not involve radicals.
- **Phenol (IV)**: When phenol reacts with NaOH and CO₂, it undergoes a carboxylation reaction, which also does not involve a radical mechanism.

2. **Determine the Mechanism**:
- **Toluene (I) + Br₂/hv**: This reaction proceeds through a radical mechanism (Substitution).
- **Acetophenone (II) + NaOH/Br₂**: This is a haloform reaction, not a radical mechanism.
- **Benzaldehyde (III)**: This does not proceed through a radical mechanism.
- **Phenol (IV) + NaOH/CO₂**: This is a carboxylation reaction, not a radical mechanism.

3. **Match the Correct Combination**:
- The only compound that undergoes a reaction through a radical mechanism is **Toluene (I)** with **Br₂/hv** which corresponds to **Substitution (R)**.

### Conclusion:
The only correct combination in which the reaction proceeds through a radical mechanism is:
- **(I) Toluene with (ii) Br₂/hv leading to (R) Substitution**.

### Final Answer:
The correct combination is (I, ii, R).

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