Arrange the following in increasing number of carbon atoms.
A. Ribose
B. Maltose
C. Glycogen
D. Gluconic Acid
Choose correct answer from options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A, D, B, C
Carbohydrates are classified by the number of sugar units they give on hydrolysis, and this decides their number of carbon atoms:
Monosaccharides: one unit, usually 5 C (pentoses) or 6 C (hexoses).
Disaccharides: two hexose units, 12 C (\( \ce{C12H22O11} \)).
Polysaccharides: hundreds or thousands of units, (C6H10O5)n.
Matching the given compounds:
A. Ribose: a pentose, \( \ce{C5H10O5} \): 5 carbon atoms.
D. Gluconic Acid: made by oxidising the –CHO group of glucose to –COOH with bromine water, so it keeps the six carbons of glucose, \( \ce{C6H12O7} \): 6 carbon atoms.
\( \displaystyle \ce{CHO-(CHOH)4-CH2OH} \xrightarrow{\ce{Br2}\text{ water}} \ce{COOH-(CHOH)4-CH2OH} \)
B. Maltose: a disaccharide of two α-D-glucose units, \( \ce{C12H22O11} \): 12 carbon atoms.
C. Glycogen: a highly branched polymer of glucose, (C6H10O5)n: thousands of carbon atoms.
Shortcut: Ribose (A) has the fewest carbon atoms and the polysaccharide glycogen (C) the most. Only Option (1) starts with A and ends with C.