An electron is in an excited state in a hydrogen like atom. It has a total energy of -3.4 eV. The kinetic energy of electron is E and its de Broglie wavelength is λ

Potential energy =−2× Kinetic energy =−2E Total energy =−2E+E=−3.4eV=−E or  E=3.4eVp= momentum, m= mass of electron E=p22m or  p=2mE =2×9.1×10−31×3.4×1.6×10−19≈10−24 de Brogile wavelength λ=hp=h2mE=6.6×10−10