Question

Which of the following(s) is/are optically inactive?

• A.
• B.
• C.
• D.

Answer 1

Answer: (A), (B), (D)

For a biphenyl to be optically active it should have bulky groups at ortho position and the two group at ortho position of each phenyl ring should be different.

In compound (a), same $-I$ groups are present at ortho position of single phenyl ring. Hence, it optically inactive.

In compound (b) and (d), no bulky groups are present at ortho position so there wont be any restricted rotation between biphenyls. Hence, they are optically inactive.

In compound (c), bulky $-S{O}_{3}H$ groups are present at ortho positions and are different with respect to each phenyl ring. Hence, it is optically active.