Q. According to Bohr's theory of the hydrogen atom, the radii $r_{n}$ of stationary electron orbits are related to the principal quantum number $n$ as :

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A

$r_{n} \propto 1 / n^{2}$

B

$r_{n} \propto 1 / n$

C

$r_{n} \propto n$

D

$r_{n} \propto n^{2}$

Solution:

As radius of $n^{\text {th }}$ orbit of hydrogen atom is given as
$r_{n}=\frac{h^{2}}{4 \pi^{2} K e^{2} m} \times \frac{n^{2}}{Z}$

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