Fructose is a ketohexose. The keto group is positioned at which carbon

Carbon 2

The correct answer is Option (1) → Carbon 2

In fructose, the keto group is positioned at Carbon 2.

Fructose is classified as a ketohexose because it contains six carbon atoms ("hexose") and a ketone functional group ("keto").

Structural Details

• Chain Structure: While glucose has an aldehyde group at Carbon 1 (making it an aldohexose), fructose has its carbonyl group ($C=O$) at the second carbon.
• Carbon 1: In fructose, Carbon 1 is a primary alcohol group ($-CH_2OH$).
• Cyclization: When fructose forms a cyclic structure (furanose), the oxygen on Carbon 5 reacts with the ketone at Carbon 2 to form a five-membered ring.