Q. In hydrogen atom, if the difference in the energy of the electron in $n = 2$ and $n = 3$ orbits is $E$, the ionization energy of hydrogen atom is

A) $13.2\ E$
B) $7.2\ E$
C) $5.6\ E$
D) $3.2\ E$
Explanation

(b) Energy $E = K\left\lbrack \frac{1}{n_{1}^{2}} - \frac{1}{n_{2}^{2}} \right\rbrack$ ($K$ = constant)
$n_{1} = 2$ and $n_{2} = 3$, so $E = \left\lbrack \frac{1}{2^{2}} - \frac{1}{3^{2}} \right\rbrack = K\left\lbrack \frac{5}{36} \right\rbrack$
For removing an electron, $n_{1} = 1$ to $n_{2} = \infty$
Energy $E_{1} = K\lbrack 1\rbrack = \frac{36}{5}E = 7.2E$
$\therefore$ Ionization energy $= 7.2\ E$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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