An alkene $\mathrm{X}\left(\mathrm{C}_4 \mathrm{H}_8\right)$ does not exhibit cis trans isomerism. Reaction of X with $\mathrm{Br}_2$ in the presence of UV light gave Y. What is Y?

Question

An alkene $\mathrm{X}\left(\mathrm{C}_4 \mathrm{H}_8\right)$ does not exhibit cis trans isomerism. Reaction…