frequency of a photon emitted due to transition of electron of a cerrain element from `L to K `shell is found to be `4.2 xx 10^(18) Hz` using moseley 's law, find the atomic number of the element , given that the Rydberg's constant `R = 1.1 xx 10^(7) m^(-1)`

Answer

B, D

Explanation

According to bohr 's model , the energy released during transition from `n_(2) to n_(1) `is given by
`delta E = hv = Rhc(Z - b)^(2)[(1)/(n_(1)^(2)) - (1)/(n_(2)^(2))]`
for transition from `L` shell to `K` shell
`h = 1 , n_(2) = 2 , n_(1) = 1 `
`:. (Z -1)^(2) Rhc[(1)/(1) -(1)/(4)] = hv`
on putting the value at `R = 1.1 xx 10^(7) m^(-1)` (given)`
`c = 3 xx 10^(6) m//s ` we get
`Z = 42`