If the binding energy of electrons in a metal is 250 kJ `"mol"^(-1)` , what is the threshold frequency of the striking photons ?

Explanation

Binding energy of 1 mole of electrons = 250 kJ
`:.` Binding energ of 1 electron `= (250)/(6.022 xx 10^(23)) kJ = 4.15 xx 10^(-22) kJ = 4.15 xx 10^(-19) J`
Threshold energy `(hv_(0))` = Binding energy
`:. hv_(0) = 4.15 xx 10^(-19) J`
or `v_(0) = (4.15 xx 10^(-19)J)/(h) = (4.15 xx 10^(-19) J)/(6.626 xx 10^(-34) Js) = 6.26 xx 10^(14) s^(-1)`