Which one of the following reacts with Grignard reagent to form an addition product which can be hydrolysed to a carboxylic acid?

Options

A. `O_(2)`
B. `CO_(2)`
C. `SO_(2)`
D. None

Answer

To solve the question of which reagent reacts with a Grignard reagent to form an addition product that can be hydrolyzed to a carboxylic acid, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Grignard Reagents**: Grignard reagents are organomagnesium compounds, typically represented as R-MgX, where R is an alkyl or aryl group and X is a halogen. They act as nucleophiles due to the presence of the carbon atom bonded to magnesium.

2. **Identifying the Reaction**: We need to find a reagent that can react with the Grignard reagent to form an addition product. The product should be capable of undergoing hydrolysis to yield a carboxylic acid.

3. **Considering Carbon Dioxide (CO2)**: One common reagent that fits this requirement is carbon dioxide (CO2). When a Grignard reagent (R-MgX) reacts with CO2, the nucleophilic carbon from the Grignard reagent attacks the electrophilic carbon in CO2.

4. **Formation of the Addition Product**: The reaction can be represented as follows:
- R-MgX + CO2 → RCOO-MgX
Here, RCOO- is the carboxylate ion formed from the addition of the Grignard reagent to carbon dioxide.

5. **Hydrolysis of the Addition Product**: The next step involves hydrolysis of the carboxylate ion:
- RCOO-MgX + H2O → RCOOH + Mg(OH)X
This reaction results in the formation of a carboxylic acid (RCOOH) and a magnesium hydroxide salt.

6. **Conclusion**: Therefore, the reagent that reacts with the Grignard reagent to form an addition product that can be hydrolyzed to a carboxylic acid is carbon dioxide (CO2).

### Final Answer:
The correct answer is **carbon dioxide (CO2)**.