Answer:
Wavelength of light in (nm) = 579 nm
Step-by-step explanation:
At first you find out the amount of energy needed to just eject one electron. This is given by
![(Energy)/(Avogadro's number)](https://img.qammunity.org/2021/formulas/chemistry/college/4v7p1zs154heplvkha3avzno3p0r6qbbnd.png)
this energy is given in question in kj/mole. This
is the work function of cesium for each electron is equal to the planc'k einstein equation.