The major product forms in this reaction is 2-chloro-2-methylbutane
Explanation:
HCl reacts with 2-methyl-2-butene by forming a carbocationic intermediate followed by addition of chloride ion to the carbocation.
The carbocationic intermediate is formed in intermediate step should be most stable i.e. it should have highest number hyperconjugative hydrogen atoms.
The major product forms in this reaction is 2-chloro-2-methylbutane.
Reaction mechanism and structural formula of carbocation is shown below.