Question

Which among the following compound is NOT optically active?

• A. 3 - Chloropentane
• B. 2 - Chloropentane
• C. 2 - Chloro - 3 - methyl pentane
• D. 3 - Chloro - 2 - methyl pentane

Hint:

For a molecule to be optically active, it must have at least one chiral center, i.e., a carbon attached to four different groups.

Answer 1

The Correct Option is A

Step 1: Optical activity and chirality.
A compound is optically active if it contains a chiral center (a carbon atom attached to four different groups).

Step 2: Analyzing the options.
(A) 3 - Chloropentane: Incorrect — This compound is not optically active because the carbon at position 3 is not attached to four different groups, hence no chiral center is present.
(B) 2 - Chloropentane: This compound is optically active as it has a chiral center.
(C) 2 - Chloro - 3 - methyl pentane: This compound is also optically active due to the presence of a chiral center.
(D) 3 - Chloro - 2 - methyl pentane: This compound is optically active due to a chiral center.

Step 3: Conclusion.
The correct answer is (A) 3 - Chloropentane because it lacks a chiral center and is thus not optically active.