Q 12-13-087JEE MainJEE Main 2022 (26 Jun, Shift 1)Easy
How many alpha and beta particles are emitted when uranium ${}_{92}\text{U}^{238}$ decays to lead ${}_{82}\text{Pb}^{206}$?
Answer: (D) 8 alpha particles and 6 beta particles
Mass number falls by $238 - 206 = 32$, so $\dfrac{32}{4} = 8$ alpha particles. These lower $Z$ by $16$, to $76$; to reach $82$ we need $6$ beta-minus decays.
Solution by Sreeraj P, M.Sc Physics