The work function `(phi)` of some metals is listed below. The number of metals which will show photoelectric effect when light of 300 nm wavelength falls on the metal is Metal
`{:("Metal", Li , Na, K, Mg, Cu, Ag, Fe, Pt, W),((phi), 2.4,2.3,2.2,3.7,4.8,4.3,4.7,6.3,4.75):}`

Answer

4

Explanation

Since the vaue of `hc=1240 eV nm`.
Energy corresponding to `lamda =300 nm" is "(1240 eV nm)/(300 nm) =4.134 eV`
Elements having `phi lt 4.134 eV` will show photoelectric effect, are Li, Na, K, and `Mg rarr 4`
So, number of metals showing photo-electric will be four, i.e., Li, Na, K, and Mg.