Question

What are N and M?

Answer 1

Isomers are the compounds having the same molecular formula but different structures. The reactions that take place in the presence of Chlorine and sunlight (hv) are called halogenations, and halogens (Cl) are substituted in the product.

Complete step-by-step answer: We have been given a compound, that reacts with chlorine in the presence of sunlight to have a substitution reaction where it forms compounds of the formula, ${{C}_{5}}{{H}_{11}}Cl$. We have to calculate the number of isomers that this compound can have.
Next we have to calculate among these isomers, the isomers when subjected to fractional distillation, how many isomers will be left after the distillation, or those isomers that cannot be separated by fractional distillation.
The compound given, will proceed the reaction and form the following:

It will form 6 isomers on substitution reaction. Among them 4 are enantiomers that have d and l configuration. So the number N = 6. Among these isomers, 4 isomers remain after fractional distillation, these are the d and l configuration of isomers. So, M = 4.
Hence, N = 6 isomeric products and M = 4 isomeric products.

Note: The d and l configuration has the characteristic to rotate the plane polarized light towards right and left respectively. They cannot be separated by fractional distillation as the enantiomer pairs have very identical boiling points. So, other 2 isomers will get removed due to difference in boiling point while these enantiomers remain after fractional distillation.