Assuming that the bohr model is valid, what is the kinetic energy of a photoelectron liberated by a photon with a the given wavelength from a state with given z and n

The kinetic energy of the photoelectron is exactly equal to the energy of the liberating photon. You can determine this energy from the wavelength of the liberating photon with the following equation:

E = h. c / wavelength

where E = energy,

h = planks constant (6.626 x10^-34)

c = speed of light (2.9 x10^8)