Q. The frequency of 1$^{st}$ line of Balmer series in $H_{2}$ atom is $v_{0}$. The frequency of line emitted by singly ionized $He$ atom is
A) $2v_{0}$
B) $4v_{0}$
C) $v_{0}/2$
D) $v_{0}/4$
Explanation
(b) $v \propto Z^{2} \Rightarrow \frac{v_{H_{2}}}{v_{He}} = \left( \frac{1}{2} \right)^{2} = \frac{1}{4} \Rightarrow v_{He} = 4v_{H_{2}} = 4v_{0}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.