Q. If the energy of a hydrogen atom in $n$th orbit is $E_{n}$, then energy in the $n$th orbit of a singly ionized helium atom will be
A) $4E_{n}$
B) $E_{n}/4$
C) $2E_{n}$
D) $E_{n}/2$
Explanation
(a) $E_{n} \propto Z^{2} \Rightarrow \frac{\left( E_{n} \right)_{He}}{\left( E_{n} \right)_{H}} = \frac{Z_{He}^{2}}{Z_{H}^{2}} = 4 \Rightarrow \left( E_{n} \right)_{He} = 4 \times \left( E_{n} \right)_{H}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.