Question

Assertion
Statement 1: Molecules that are not superimposable on their mirror images are chiral.
Reason:
A.Statement 2: All chiral molecules have chiral centers.
B.Statement 1 is true, Statement 2 is true; Statement 2 is a correct explanation for Statement 1.
C.Statement 1 is true, Statement 2 is true; Statement 2 is NOT a correct explanation for Statement 1.
D.Statement 1 is true, statement 2 is false.
E.Statement 1 is false, statement 2 is true.

Answer 1

Hint:A molecule is said to be chiral if it cannot be superimposed on its mirror image by any combination of rotations and translations. A chiral molecule exists as two stereoisomers that are mirror images of each other called enantiomers. Enantiomers are distinguished based on their absolute configuration. They have the same chemical properties but different physical properties. A homogeneous mixture of two enantiomers is called a racemic mixture. In chiral organic molecules, a stereocenter is an asymmetric carbon, multiple stereocenters may give rise to additional stereoisomers. Chirality is based on molecular symmetry; A chiral molecule cannot have an improper axis of rotation which includes planes of symmetry and inversion center.

Complete step by step answer:
We will analyze both the statements. Statement 1 : Molecules that are not superimposable on their mirror images are chiral.
This statement is true as molecules that are not superimposable on their mirror images are asymmetric and hence chiral. Such molecules are known as enantiomers. These molecules when placed on top of one another will not give the same molecule hence they are chiral. Therefore, we can conclude that statement 1 is true.
Statement 2 is: All chiral molecules have chiral centers. All chiral molecules don't have to have a stereogenic center. A molecule can be chiral even if it does not have a stereocenter. A molecule’s chirality depends entirely on whether it is asymmetrical. Example-Biphenyls do not have a chiral carbon but they cannot rotate freely due to steric crowding. Hence, they are asymmetrical. Therefore, we can conclude that statement 2 is false.
Hence option (C) is the correct answer.

Note:
A molecule with stereocenters need not be chiral always.
In chiral organic compounds, a stereocenter is often an asymmetric carbon.
A molecule that has no plane, center, or axis of symmetry is asymmetric.
Asymmetric molecules are always chiral.