The correct structure of D-Fructose is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → D-fructose (C-3 –OH on the left, C-4 and C-5 –OH on the right)
Fructose is a ketohexose, \( \ce{C6H12O6} \): its carbonyl group is a keto group at C-2, with \( \ce{CH2OH} \) groups at C-1 and C-6. It has three chiral carbons, C-3, C-4 and C-5, whose configuration is the same as C-3, C-4 and C-5 of D-glucose:
C-3: –OH on the left
C-4: –OH on the right
C-5: –OH on the right; this is the lowest chiral carbon, and –OH on the right is what makes it a D-sugar.
Structure 2 has the C=O at C-2, HO on the left at C-3 and OH on the right at C-4 and C-5. So it is D-fructose.
Why the other options are incorrect
Option (1) — Incorrect. The –OH at C-3 is on the right; all three –OH groups on one side give a different ketohexose, not fructose.
Option (3) — Incorrect. The –OH groups at C-3 and C-4 are the wrong way round (C-3 on the right, C-4 on the left).
Option (4) — Incorrect. All three –OH groups are on the left; with the C-5 –OH on the left this is an L-sugar.
NCERT (2026-27 edition):
Fructose
