Q. When hydrogen atom is in its first excited level, its radius is how many times its ground state radius?
A) Half
B) Same
C) Twice
D) Four times
Explanation
(d) For ground state, $n = 1$
For first excited state, $n = 2$
As $r \propto n^{2}$
$\therefore$ radius becomes 4 times.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.