Which of the following statement is not true about glucose?

Options

A. It is an aldohexose
B. On heating with HI it forms n-hexane
C. It is present in furanose form
D. It does not give 2, 4-DNP test.

Explanation

To determine which statement is not true about glucose, we will analyze each statement provided in the context of glucose's structure and properties.

### Step-by-Step Solution:

1. **Identify the Molecular Formula of Glucose**:
- Glucose has the molecular formula C₆H₁₂O₆. This is a true statement.

2. **Determine the Type of Sugar**:
- Glucose is classified as an aldohexose because it contains an aldehyde group (-CHO) and has six carbon atoms. This statement is also true.

3. **Examine the Reaction with HI**:
- When glucose is heated with hydrogen iodide (HI), it can be converted to n-hexane, indicating that glucose has a straight-chain structure. This statement is true as well.

4. **Analyze the Ring Structure**:
- Glucose can exist in cyclic forms, primarily as a pyranose (six-membered ring) and furanose (five-membered ring). The statement that glucose is present in a furanose ring is incorrect because glucose predominantly forms a pyranose ring. This is the statement that is not true.

5. **Consider the 2,4-DNP Test**:
- The 2,4-dinitrophenylhydrazine (2,4-DNP) test is used to detect aldehydes and ketones. In the cyclic form of glucose, the aldehyde group is not free, so glucose does not give a positive result in this test. This statement is true.

### Conclusion:
The statement that is not true about glucose is that it is present in a furanose ring. Glucose primarily exists in a pyranose ring structure.