An element of atomic number 9 emits `K_(alpha)` X-ray of wavelength `lamda`. Find the atomic number of the element which emits `K_(alpha)` X-ray of wavelength `4lamda`.

Options

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

Answer

C

Explanation

For `K_(alpha)rArrsqrt(v)prop(z-1) rArr(1)/(sqrt(lambda))prop(z-1)`
or `(1)/((z-1)^(2))`.....(i)
`4lambdaprop(1)/((z'-1)^(2))`.....(ii)
`rArr (1)/(4)=((z'-1)^(2))/((z-1)^(2)) rArr(z'-1)/(z-1)=(1)/(2)`
`rArr 2z'-2=z-1 rArr2z'-2=11-1=10 rArr z'=6`