Which of the following statements 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 option provided in the question.

### Step-by-Step Solution:

1. **Understanding Glucose Structure**:
- Glucose is a simple sugar (monosaccharide) that exists in two forms: acyclic (open-chain) and cyclic (ring form).
- The acyclic form of glucose has an aldehyde group and six carbon atoms, making it an aldohexose.

2. **Analyzing the Statements**:
- **Statement A**: "It is an aldohexose."
- This statement is true because glucose has an aldehyde group and six carbon atoms.

- **Statement B**: "On treating with HI, it forms n-hexane."
- This statement is also true. When glucose is treated with hot HI, the hydroxyl (OH) groups are replaced by hydrogen (H), resulting in n-hexane, a straight-chain alkane with six carbon atoms.

- **Statement C**: "It is present in a purinose form."
- This statement is false. Glucose primarily exists in a pyranose form (six-membered ring) and not in a purinose form (which refers to a five-membered ring structure). Therefore, this is the incorrect statement.

- **Statement D**: "It does not give the 2,4-DNP test."
- This statement is true. The 2,4-DNP test is used to detect free aldehyde or ketone groups. In the cyclic form of glucose, the aldehyde group is not free, so it does not give a positive result for the 2,4-DNP test.

3. **Conclusion**:
- The statement that is not true about glucose is **C**: "It is present in a purinose form."

### Final Answer:
The incorrect statement is **C**: "It is present in a purinose form."

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