It takes 261 kj/mol to eject electrons from a certain metal surface. what is the longest wavelength of light (nm) that can be used to eject electrons from the surface of this metal via the photoelectric effect?

 459 nm

Explanation:

The relation between energy and wavelength of light is given by Planck's equation, which is:

where,

E = energy of the light  =   (1kJ=1000J)

N= avogadro's number  =

h = Planck's constant  =

c = speed of light  =

= wavelength of light  = ?

Putting the values in the  equation:

Thus the longest wavelength of light that can be used to eject electrons from the surface of this metal via the photoelectric effect is 459 nm