Question

A compound whose molecule is superimposable on its mirror image despite containing chiral carbon atoms is:
(A) Threo isomer
(B) Meso compound
(C) Enantiomer
(D) None of the above

Answer 1

Hint: A compound whose molecules are superimposable on its mirror image despite containing chiral carbon atom is called meso compound.

Complete step by step answer:
Chiral carbon is also known as asymmetric carbon. When four valencies of carbon atom are satisfied by different groups, then C atom is known as asymmetric carbon.
Example: 2-chlorobutane

Here, four valencies satisfied by $ - H, - C{H_3}, - {C_2}{H_5}$and $ - Cl$group.
Threo: Compounds having two different chiral or asymmetric carbon atoms are named by using prefix threo.
Enantiomers: Enantiomers are chiral molecules that are mirror images of one another.
The molecules are non-superimposable on one another. This means that molecules cannot be placed on top of one another and give the same molecules. Enantiomers have same chemical and physical properties, but differ in the effect on plane polarized light. They rotate plane polarized light in equal but opposite direction.
Example: 2-chlorobutane.


Meso: Meso compounds are superimposable on its mirror image. So they are non-optically active members of a set of stereoisomers at least two of which are optically active

Thus, Option C is correct.
Note:
Four different groups should be bonded to chiral carbon. If two of them are the same then C-atom is not chiral.