Q. The Bohr’s orbit radius for the hydrogen atom ($n = 1$) is approximately 0.53Å. The radius for the first excited state ($n = 2$) orbit is
A) 0.27 Å
B) 1.27 Å
C) 2.12 Å
D) 3.12 Å
Explanation
(c)
Radius of $n$th orbit of hydrogen atom =$0.529n^{2}$
where, $n =$no. of orbit $= 2$
$\therefore\ \ \ \ \ \ \ \ \ \ r_{2} = 0.529 \times (2)^{2} = 2.116\mathring{\mathrm{A}} = 2.12\mathring{\mathrm{A}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.