Answer:
X is 3-chloro-2,4-dimethylpentane
Step-by-step explanation:
The radical chlorination of 2,4-dimethylpentane may give three products.
Based on the information that
i) both the products gives single alkene on elimination and
ii) both the products also undergoes SN2 reaction but Y reacts faster than X
We may conclude that as SN2 reaction is faster in primary alkyl halides as compared to secondary or tertiary so Y must be primary or secondary and it cannot be tertiary alkyl halide.
The possible products are shown in the figure.
The structure of X is shown in the figure.