A radioactive nucleus with Z = 92 and A = 235 decays through a series of alpha,beta,and gamma emissions to a stable nucleus with Z = 82 and A = 207.The number of alpha particles and the number of beta particles emitted during the entire process are
A)8 alpha particles and 6 beta particles.
B)7 alpha particles and 4 beta particles.
C)7 alpha particles and 10 beta particles.
D)14 alpha particles and 7 beta particles.
E)None of these is correct.

Question

Quizplus · Accepted Answer

The decay chain of the given radioactive nucleus is: 
U-235 → α + Th-231 → β- + Pa-231 → β- + U-231 → α + Th-227 → α + Ra-223 → α + Rn-219 → α + Po-215 → α + Pb-211 → β- + Bi-211 → α + Tl-207 → β- + Pb-207

Counting the number of alpha and beta emissions in the decay chain, we get 7 alpha particles and 4 beta particles. Therefore, the answer is B.

A Radioactive Nucleus with Z = 92 and a =