Question

If the speed of the electron in third orbit of hydrogen atom is x, then the speed of the electron in the first Bohr's orbit is:

• A. $\frac{x}{2}$
• B. 3x
• C. $\frac{x}{3}$
• D. 9x

Answer 1

The correct option is B 3x

Speed of the electron in the $n^{th}$ orbit of hydrogen atom = $\frac{2.18\times {10}^6}{n}m{s}^{-1}$

Speed of the electron in the third orbit = $\frac{2.18\times {10}^6}{3}$ $m{s}^{-1}$ = x
or $2.18\times {10}^6=3x$
$\Rightarrow$ Therefore speed of the electron in the first orbit = $\frac{2.18\times {10}^6}{1}$ $m{s}^{-1}$ = 3x