JEE Chemistry 2024 Question with Solution

Given: Four statements about glucose are given.

Find: The incorrect statement.

Check each option using known properties of glucose.

1. Option A: Glucose is soluble in water because of having an aldehyde functional group.

This is incorrect. Glucose is highly soluble in water mainly because it contains multiple $-\text{OH}$ groups. These hydroxyl groups form hydrogen bonds with water. The aldehyde group is not the primary reason for its solubility.

2. Option B: Glucose remains in multiple isomeric forms in its aqueous solution.

This is correct. In aqueous solution, glucose exists in equilibrium among open-chain and cyclic forms, including $\alpha$ and $\beta$ anomers.

3. Option C: Glucose is an aldohexose.

This is correct. Glucose has six carbon atoms and contains an aldehyde group in its open-chain form, so it is an aldohexose.

4. Option D: Glucose is one of the monomer units in sucrose.

This is correct. Sucrose is made of glucose and fructose units.

Therefore, the incorrect statement is Option A.

Given: Statements about the structure and properties of glucose.

Find: Which statement is false.

The key idea is that solubility of carbohydrates in water depends strongly on the number of hydroxyl groups available for hydrogen bonding.

• Glucose has several $-\text{OH}$ groups, so it dissolves readily in water.
• In aqueous solution, it shows mutarotation because different cyclic and open-chain forms coexist.
• It is an aldohexose because it is a six-carbon sugar with an aldehyde functionality in the open-chain form.
• Sucrose is a disaccharide formed from glucose and fructose.

Hence the statement attributing water solubility mainly to the aldehyde group is the incorrect one.

The correct option is A.