Which of the statement is incorrect.

Options

A. Fructose on reduction with `NaBH_(4)` gives only one product.
B. Solubility of amino acid at its isoelectric point is minimum.
C. Guanidline is more basic than diethyl amine
D. Mutarotation is observed in the aqueous solution of glucose.

Explanation

To determine which statement is incorrect regarding the reduction of fructose with sodium borohydride (NaBH4), we can analyze the reduction process step by step.

### Step-by-Step Solution:

1. **Identify the Structure of Fructose**:
- Fructose is a ketose sugar with the molecular formula C6H12O6. Its structure can be represented as:
```
CH2OH
|
H - C - OH
|
HO - C - H
|
H - C - OH
|
CH2OH
```

2. **Understand the Reduction Reaction**:
- Sodium borohydride (NaBH4) is a reducing agent that can reduce ketones and aldehydes to alcohols. Fructose, being a ketose, will undergo reduction at its carbonyl group.

3. **Products of the Reduction**:
- When fructose is reduced by NaBH4, it does not yield a single product. Instead, it can produce two different sugar alcohols:
- **D-mannitol**: This is formed when the carbonyl group is reduced to an alcohol, resulting in a structure that has two alcohol groups on adjacent carbons.
- **D-sorbitol**: This is another sugar alcohol that can also be formed from the reduction of fructose.

4. **Conclusion**:
- The statement that "fructose on reduction with NaBH4 gives only one product" is incorrect. The reduction of fructose yields two products: D-mannitol and D-sorbitol.

### Final Answer:
The incorrect statement is: "Fructose on reduction with NaBH4 gives only one product."