Statement-I: Unlike the `gtC=O` group of aldehydes and ketones, the `C=O` of `R-overset(O)overset(||)C-OH` does not undergo nucleophilic addition reactions.
Because
Statement-II: Carboxylic acids exist as dimers due to intermolecular hydrogen bonding in aprotic medium.

Options

A. Statement-I is True, Statement-II is True : Statement-II is a correct explanation for Statement-I
B. Statement-I is True, Statement-II is True : Statement-II is `NOT` a correct explanation for Statement-I
C. Statement-I is True, Statement-II is False.
D. Statement-I is False, Statement-II is True.

Answer

To analyze the given statements, we will break down the reasoning behind each statement step by step.

### Step 1: Understanding Statement-I
**Statement-I:** Unlike the `C=O` group of aldehydes and ketones, the `C=O` of carboxylic acids (`R-COOH`) does not undergo nucleophilic addition reactions.

- **Explanation:** In aldehydes and ketones, the carbonyl carbon is electrophilic due to the difference in electronegativity between carbon and oxygen. The oxygen atom carries a partial negative charge, while the carbon carries a partial positive charge, making it susceptible to nucleophilic attack.
- In carboxylic acids, the carbonyl carbon is less electrophilic because the presence of the hydroxyl group (`-OH`) and the resonance stabilization provided by the adjacent oxygen atoms increases the electron density on the carbonyl carbon. This reduced electrophilicity makes the carbonyl carbon less reactive towards nucleophiles.

### Step 2: Understanding Statement-II
**Statement-II:** Carboxylic acids exist as dimers due to intermolecular hydrogen bonding in aprotic medium.

- **Explanation:** Carboxylic acids can form dimers through hydrogen bonding. In an aprotic medium (solvents that do not donate protons), such as DMSO or THF, carboxylic acids can still form dimers because the hydrogen bonding occurs between the `-OH` group of one molecule and the carbonyl oxygen of another molecule. This dimerization is a significant factor in the properties of carboxylic acids.

### Step 3: Evaluating the Relationship Between the Statements
- **Statement-I** is true as carboxylic acids do not undergo nucleophilic addition reactions due to the reasons discussed.
- **Statement-II** is also true as carboxylic acids can form dimers in aprotic solvents due to hydrogen bonding.
- However, Statement-II does not explain Statement-I. The reason for the lack of nucleophilic addition in carboxylic acids is due to the increased electron density on the carbonyl carbon, not directly due to dimerization.

### Conclusion
Both statements are correct, but Statement-II does not serve as an explanation for Statement-I. Therefore, the correct answer is:

**Option B:** Both statements are correct, but Statement-II is not the correct explanation of Statement-I.

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