The wavelength of `K_(alpha)` line in copper is `1.54 Å`. The ionisation energy of `K` electron in copper in Joule is

Options

A. `11.2 xx 10^(-27)`
B. `12.9 xx 10^(-16)`
C. `1.7 xx 10^(-15)`
D. `10 xx 10^(-16)`

Answer

B

Explanation

Required ionisiation energy
`= (hc)/(lambda) = (6.6 xx 10^(-34) xx 3 xx 10^(8))/(1.54 xx 10^(-10)) J = 12.9 xx 10^(-19) J`