Consider the following statements about fructose.
(A) Fructose contains a ketonic functional group at carbon number 2.
(B) Fructose has six carbon atoms in a straight chain, as in the case of glucose.
(C) The cyclic forms of fructose are obtained by the addition of the –OH at C6 to the >C=O group.
(D) Furan is a five membered cyclic compound with one oxygen atom and four carbon atoms.
Which of the statements given above are correct? Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (B) and (D) only
Fructose is an important ketohexose with the same molecular formula as glucose, C6H12O6. Its ring is formed when an –OH group adds to the keto group, and the ring is five-membered.
(A) Fructose contains a ketonic functional group at carbon number 2. — True. The >C=O group is at C2, with a CH2OH group on each side of it.
(B) Fructose has six carbon atoms in a straight chain, as in the case of glucose. — True. Like glucose, fructose has an unbranched chain of six carbon atoms.
(C) The cyclic forms of fructose are obtained by the addition of the –OH at C6 to the >C=O group. — False. It is the –OH at C5.
C2 to C5 and the ring oxygen make a five-membered ring, the furanose ring; the –OH at C6 would give a six-membered ring.
(D) Furan is a five membered cyclic compound with one oxygen atom and four carbon atoms. — True. The five-membered ring of fructose is named furanose after furan.
NCERT (2026-27 edition):
10.1.2.2 Fructose – “Fructose also has the molecular formula C6H12O6 and on the basis of its reactions it was found to contain a ketonic functional group at carbon number 2 and six carbons in straight chain as in the case of glucose.”
“It also exists in two cyclic forms which are obtained by the addition of —OH at C5 to the (>C=O) group. The ring, thus formed is a five membered ring and is named as furanose with analogy to the compound furan. Furan is a five membered cyclic compound with one oxygen and four carbon atoms.”