When electromagnetic radiation of wavelength 300 nm falls on the surface of a metal, electrons are emitted with the kinetic energy of 1.68 × 105 J mol–1. The minimum energy needed to remove one mole of electron from the metal is:
(h = 6.626 × 10–34 Js, c = 3 × 108 ms–1, NA = 6.022 × 1023 mol–1)