Q. A radioactive nucleus with $Z$ protons and N neutrons emits an $\alpha$-particle, $2\beta$-particles and 2 gamma rays. The number of protons and neutrons in the nucleus left after the decay respectively, are
A) $Z - 3,N - 1$
B) $Z - 2,N - 2$
C) $Z - 1,N - 3$
D) $Z,N - 4$
Explanation
(d) (With emission of an $\alpha$ particle $(\ _{2}He^{4}$) mass number decreases by 4 unit and atomic number decrease by 2 units and with emission of $2\beta^{- 1}$ particles atomic number increases by 2 units. So Z will remain same and $N$ will become $N - 4$)
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.