Question

The compound Bromochlorofluoromethane is:

• A. Nonsuperimposable on its mirror image
• B. Chiral
• C. Optically active
• D. The central Carbon atom is a chiral center

Answer 1

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

The correct options are
A Nonsuperimposable on its mirror image
B Chiral
C Optically active
D The central Carbon atom is a chiral center

First, look at the central carbon. Is it $s{p}^3$ hybridized? Definitely. Can you recall the definition of a chiral center?
A chiral center is any $s{p}^3$ hybridized atom attached to 4 different groups. One notable exception is a tertiary amine which undergoes rapid flipping and hence cannot be categorized as a chiral center.
Also, there are four different groups attached to the central Carbon atom. Hence, it is a chiral center. But does that make the molecule chiral?
What is a chiral molecule? A molecule whose image is not superimposable on the original is called chiral. Such molecules rotate plane polarized light and are called optically active. Do note that if a compound has only one center, it usually tends to be chiral. But the presence of a chiral center alone is neither a necessary nor a sufficient condition for the molecule to be called chiral. Let us do the mirror test:

If we try to superimpose the F - C - Cl bonds, we see that the other elements do not coincide. In other words, there is a lateral inversion and this makes the mirror image non-superimposable on top of the original (to the left). The image and the original are non-identical. Hence all the options are correct.