How many monochloro constitutional isomers would the reaction of 2-methylbutane with chlorine in the presence of light produce?

There are 4 monochloro isomers possible

Explanation:

The monochlorination of 2-methyl butane has 4 monochloro isomers, with different grade of abundance.

33 % 2-chloro-3-methylbutane

30 % 1-chloro-2-methylbutane

22 % 2-chloro-2-methylbutane

15 % 1-chloro-3-methylbutane.

33 % 2-chloro-3-methylbutane is the most stable; 15 % 1-chloro-3-methylbutane is the less stable.

Of those 4 monochloro isomers, there are two chiral compounds possible

⇒ 2-chloro-2-methylbutane

⇒ 2-chloro-3-methylbutane.