Answer
Copper and iron.
Work Step by Step
In this problem, the value of hc is useful. Use the result stated in Problem 29, $hc=1240\;eV \cdot nm$.
The most energetic photon of visible light has the highest frequency and the shortest wavelength. Assume a wavelength of 400 nm. Calculate the energy for such a photon.
$$hf_{max}=\frac{hc}{\lambda_{min}}=\frac{1240\;eV \cdot nm }{400nm}=3.1eV$$
Electrons will not be ejected by visible light if the metal’s work function is greater than this.
This is true for copper and iron.
