Work function of some metals are given below

Metal →	Li	K	Fe	Cu
W0(ev)→	2.42	2.25	4.7	4.8

The number of metals which will show photoelectric effect when light of 300 nm wavelength falls on the given metal is.

Energy in eV = 12400/wavelength (in 0A)
E = 12400/3000 = 4.13eV
As the energy of incident radiation in 4.13eV, the metals whose work function is less than 4.13eV will observe photo electric effect. i.e.. Li and K.