Question

Which compound is optically inactive out of the following? n-propyl chloride, secondary butyl chloride, tert-butyl chloride, isopropyl chloride.

• A. Only I, III, IV
• B. Only IV
• C. Only I, II, III
• D. Only II, III, IV

Hint:

Optical inactivity arises when a compound lacks a chiral center, which occurs when a carbon atom is bonded to two identical groups.

Answer 1

The Correct Option is A

Step 1: Understand optical activity.
A compound is optically active if it contains a chiral center, i.e., a carbon atom bonded to four different groups. If a compound lacks a chiral center, it will be optically inactive.
Step 2: Analyze each compound.
- n-propyl chloride (I): The structure of n-propyl chloride is \( \text{CH}_3\text{CH}_2\text{CH}_2\text{Cl} \), where the central carbon is attached to two hydrogen atoms, making it non-chiral. Hence, it is optically inactive. - Secondary butyl chloride (II): The structure is \( \text{CH}_3\text{CH}_2\text{CHCl} \), where the central carbon is attached to two identical groups, making it non-chiral. Therefore, it is optically inactive. - Tert-butyl chloride (III): The structure is \( (\text{CH}_3)_3\text{CCl} \), where the central carbon is bonded to three identical methyl groups. This makes it non-chiral, and it is optically inactive. - Isopropyl chloride (IV): The structure is \( \text{CH}_3\text{CHCl}\text{CH}_3 \), where the central carbon is attached to two identical methyl groups, making it non-chiral. Therefore, it is optically inactive.
Step 3: Conclusion.
All of the compounds, except for isopropyl chloride, are optically inactive because they lack a chiral center. Therefore, the correct answer is (1) Only I, III, IV.