Please help me! I am struggling in Physics right now as it is my weakest subject. This unit is really tough on me. I need all the help I can get. Please include step by step instructions/details so I can actually understand what is going on in the question.

***Please only do Question 4***

ab 2. The work function for a sodium surface is 4.08 eV. What is the maximum wavelength that an electromagnetic wave can have and still eject electrons from this surface? (/1) 3. A potassium surface has a work function of 2.24 eV. Electromagnetic waves that have a wavelength of 215 nm strike the surface and eject electrons. Find the maximum kinetic energy of the ejected electrons. Express your answer in electron volts. (/2) 4. The maximum wavelength for which an electromagnetic wave can eject electrons from a platinum surface is 196 nm. When radiation with a wavelength of 120 nm shines on the surface, what is the maximum speed of the ejected electrons? ( 13)\f