The work functions of Ag, Mg, K and Na respectively in eV are 4.3, 3.7, 2.25, 2.30. when an electromagnetic radiation of wavelength of 300 nm is allowed to fall on these metal surfaces, the number of metals from which the electrons are ejected is. `(1 eV = 1.6022 times 10^-19 J)`

Options

A. 5
B. 4
C. 3
D. 2

Answer

C

Explanation

Answer(3) Only from the metals Mg, K, Na electrons are ejected because their wavelengths are `gt ` 300 nm `(lambda = hc/phi)`