Question

Question #1905b

Answer 1

Here's my take on it.

Explanation:

If a molecule is chiral, it automatically has an enantiomer.

In introductory organic chemistry, you are pretty safe in assuming that a molecule must have four different groups attached in order to be chiral and to have an enantiomer (however, there are some molecules that are chiral despite having no chiral centres).

The maximum number of optical isomers is `2^n`, where `n` is the number of chiral centres.

However, if `n ≥ 2`, the actual number of isomers may be less, because some of the structures may represent the same meso compound.

Using a model kit is too time consuming to be practical in an exam situation.

The easiest practical way to distinguish the different isomers without using models is to draw their 3D structures (e.g. wedge-dash, sawhorse, Newman, or Fischer projections).