The ionization energy of gaseous Na atoms is `495.5 kJ "mol"^(-1)`. The lowest possible frequency of light that ionizes a sodium atom is
`(h = 6.626 xx 10^(-34) Js, N_A = 6.022 xx 10^23 "mol"^(-1))`

Options

A. `1.24 xx 10^(15) s^(-1)`
B. `7.50 xx 10^4 s^(-1)`
C. `4.76 xx 10^(14) s^(-1)`
D. `3.15 xx 10^(15) s^(-1)`

Answer

A

Explanation

One photon ionises one Na-atom by elastic collision
`NA hv_("photon")xx 10^(-3) (KJ "mole"^(-1))`
`6*022 xx 10^23 xx 6*626 xx 10^(-34) xx upsilon_("photon")xx 10^(-3) = 495*5`
`upsilon_("photon") =(495*5)/(6*022xx6*626xx 10^(-14))`
`= 12.41 xx 10^(14)`
`= 1*241 xx 10^(15) sec^(-1)`