Answer: 
Explanation:
In the photoelectric effect, the energy of the incident photon is used partially to extract the photoelectron from the metal (work function) and part is given to the photoelectron as kinetic energy:
(1)
where
hf is the energy of the photon, with h being the Planck constant and f the photon frequency
is the work function of the metal
K is the kinetic energy of the electron
In this problem, the photon hasa wavelength of
, so its frequency is

Now we can use eq.(1) to find the Kinetic energy of the photoelectron

And the kinetic energy of the electron is given by:

From which we can find the electron's velocity:
