(a) $H_{2}C = CH_{2}\overset{HBr}{\rightarrow}CH_{3}CH_{2}Br$ $(A)$ $\underset{\mathrm{\Delta}}{\overset{Alc.KOH}{\rightarrow}}H_{2}C = CH_{2}$ $(A)$ Hence, $A = C_{2}H_{4};B = \frac{alc.KOH}{\mathrm{\Delta}}\$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.