What is the threshold wavelength for a cesium surface, for which the work function is 1.8 eV ?

The threshold wavelength for a metal surface whose photoelectric work function is 3.313eV is

The threshold wavelength for a metal surface whose photoelectric work function is 3.313 eV is……………………

The threshold wavelength of a metal having work function 2 eV is 6000 Å . What will be the threshold wavelength for the metal having a work function of 6 eV ?

What is the threshold wavelength of a metal if the photoelectric work function of the metal is 5 eV?