he work function of chromium is $4\mathrm{.}40$ eV$.$

a$)$ Calculate the kinetic energy of electrons ejected from the surface when it is irradiated with $200$ nm light. $($hint: $1$ eV $=$

$1\mathrm{.}60210-19$ J$)$

b$)$ How many electrons are ejected if the light is $900$ nm $($near IR$)?$