Photoelectric effect - work function

2022 Phase 2 1 question

1. When electromagnetic radiation of wavelength 300 nm falls on the surface of a metal, electrons are emitted with the kinetic energy of $1.68\times10^5$ J mol$^{-1}$. What is the minimum energy needed to remove an electron from the metal? ($h=6.626\times10^{-34}$ Js, $c=3\times10^8$ ms$^{-1}$, $N_A=6.022\times10^{23}$ mol$^{-1}$)