Question

Glucose can be classified as an aldohexose. Name the following monosaccharide to indicate its carbonyl group and the number of carbon atoms.
HOCH2CCCCH2OH, with an oxygen atom attached to the first (from left to right) carbon atom by a double bond. Then an OH group is attached above the third and the fourth carbon atoms, while an H atom is attached below these carbon atoms, correspondingly.

Answer 1

This is a ketose with six carbons — a ketohexose (more specifically a 2‑ketohexose, e.g. fructose if the stereochemistry matches). Reason: the chain has CH2OH groups at both ends (so the C=O is internal, i.e. a ketone) and there are six carbons total.