Question

D-Erythrose and D- threose is separately reduced with $NaB{H}_4$ to give the products (A) and (B) respectively. Which of the following statements is correct about (A) and (B)?

• A. Both (A) and (B) will be optically active.
• B. Both (A) and (B) will be optically inactive.
• C. (A) will be optically inactive but (B) will be optically active.
• D. Neither (A) not (B) possesses any asymmetric carbon atom.

Answer 1

The correct option is C (A) will be optically inactive but (B) will be optically active.

As the mirror image of $A$ is symmetrical and superimposed on each other so $A$ is optically inactive.

while the mirror images of $B$ is non-superimposable and unsymmetrical so they are optically active.