Q. When a radioactive substance emits an $\alpha$-particle, its position in the periodic table is lowered by
A) One place
B) Two places
C) Three places
D) Four places
Explanation
(b) $\ _{Z}X^{A}\overset{\ \ \alpha\ \ }{\rightarrow}\ _{Z - 2}X^{A - 4}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.