Given Data:- :- $E = 75eV = 75×1.6×10^{(-19)} = 1.20 × 10^{(-17)} $

Formula :- $E= \frac{1}{2} mv^2 , λ=\frac{h}{mv}= \frac{h}{p}$

Calculations :- $ E= \frac{mv^2}{2m} = \frac{(mv)^2}{2m} = \frac{h^2}{2m\lambda^2}$

$\lambda = \frac{h}{\sqrt{2mE}} = \frac {6.63*10^{-34}}{\sqrt{2*9.1*10^{-31}*1.20*10^{-17}}} = 1.41 A^o$

Wavelength = $1.41 A^o$

frequency = $\frac {1}{\lambda} = 7.048 * 10^9 $