The vapours of Hg absorb some electrons accelerate by a potential difference of 4.5volts as a result of which light is emitted .If the full energy of single incident electron is supposed to be converted into light emitted by single Hg atom,find the wave number $\big(\large\frac{1}{\lambda}\big)$ of the light.

Question

$\begin{array}{1 1}(a)\;2.63\times 10^6m^{-1}&(b)\;4.62\times 10^6m^{-1}\\(c)\;3.63\times 10^6m^{-1}&(d)\;3.63\times 10^2m^{-1}\end{array}$