The wavelength of `K_(alpha)` X-rays of two metals `A and B` are` 4 // 1875 R and 1// 675 R`, respectively , where `R` is rydberg 's constant. The number of electron lying between `A and B` according to this lineis

Options

A. `3`
B. `6`
C. `5`
D. `4`

Answer

D

Explanation

Using `1/lambda=R(Z-1)^(2)[1/n_(1)^(2)-1/n_(2)^(2)]`
For `K_(alpha)n` Photon,`n_(1)=1,n_(2)=2`
For metal A,`(1875R)/4R(Z_(1)-1)^(2)(3/4),Z_(1)=26 B,675R=R(z_(2)-1)^(2)(3/4),z_(2)=31`
`Therefore`, 4 element lie BetweenA and B.