Which of the following statement is correct regarding gluconic acid?

Options

A. Gluconic acid is a dicarboxylic acid
B. Gluconic acid is obtained by oxidation of glucose with `HNO_3`
C. Gluconic acid can form cyclic (acetal/hemiacetal) structure
D. Gluconic acid is a partial oxidation product of glucose

Answer

To solve the question regarding gluconic acid, we need to evaluate the provided statements one by one.

### Step-by-Step Solution:

1. **Understanding Gluconic Acid Structure**:
- Gluconic acid has the structure: COOH-CHOH-CHOH-CHOH-CHOH-CH2OH. It contains one carboxylic acid group (COOH) and multiple hydroxyl groups (OH).

2. **Evaluating the Statements**:
- **Statement 1**: "Gluconic acid is a di-carboxylic acid."
- This statement is **incorrect** because gluconic acid has only one carboxylic acid group, making it a monocarboxylic acid.

- **Statement 2**: "Gluconic acid is obtained by the oxidation of glucose with ethanol."
- This statement is **incorrect**. Gluconic acid is formed when glucose is oxidized, typically using bromine water, not ethanol.

- **Statement 3**: "Gluconic acid can form cyclic acetyl hemiacetal structure."
- This statement is **incorrect**. Gluconic acid cannot form a cyclic structure because it has a carboxylic acid group instead of an aldehyde or ketone group, which are necessary for forming cyclic structures.

- **Statement 4**: "Gluconic acid is a partial oxidation product of glucose."
- This statement is **correct**. Gluconic acid is indeed formed through the partial oxidation of glucose, where only one hydroxyl group is oxidized to a carboxylic acid group.

3. **Conclusion**:
- The correct statement regarding gluconic acid is that it is a partial oxidation product of glucose. Therefore, the answer is **option 4**.