The wavelength of `K_(alpha)` line of an X-ray spectrum of an element of atomic no. Z= 11 is `lamda`.. The wavelength of same line of element of atomic no. Z' is `4lamda`, then Z' is :

Options

A. 4
B. 6
C. 44
D. 11

Answer

B

Explanation

By Mosley.s law
`v=^(2)(z-b)^(2)`
`(v_(1))/(v_(2))=((z_(1)-b)^(2))/((z_(2)-b)^(2))`
But `v=(c)/(lambda)`
`(lambda_(2))/(lambda_(1))=((z_(1)-1)^(2))/((z_(2)-1)^(2))`
`(4lambda)/(lambda)=((11-1)^(2))/((z.-1)^(2))=4`
Then `z=6`