Question

What is the number of chiral carbon atoms and number of formyl groups respectively present in ribose?

• A. 2 and 2
• B. 2 and 1
• C. 3 and 1
• D. 3 and 2

Hint:

Aldopentose rule: Number of chiral centres = (n-2) = 5-2 = 3

Answer 1

The Correct Option is C

Concept: Ribose is an aldopentose sugar (5-carbon sugar with an aldehyde group).

Step 1: Write structure of ribose.
\[ \text{CHO} - \text{(CHOH)}_3 - \text{CH}_2\text{OH} \]

Step 2: Count chiral carbons.
• C2, C3, C4 are chiral
• C1 (aldehyde) and C5 (CH$_2$OH) are not chiral Thus, number of chiral carbons = 3

Step 3: Count formyl groups.
Formyl group = $-\text{CHO}$ Only one such group present at C1.

Step 4: Conclusion.
Thus, ribose has 3 chiral carbons and 1 formyl group. Final Answer: Option (C)