Question

At what minimum atomic number, a transition from n = 2 to n = 1 energy level would result in the emission of x-ray with $\lambda =3.0\times {10}^{-8}m$

• A. 2
• B. 3
• C. 4
• D. 5

Answer 1

The correct option is A 2

$\frac{1}{\lambda }=R{z}^2(\frac{1}{n_1^2}-\frac{1}{n_2^2})$

$\frac{1}{3\times {10}^{-8}}=1.1\times {10}^7{z}^2[\frac{1}{1^2}-\frac{1}{2^2}]$

$z^2=\frac{4}{3\times {10}^{-8}\times 1.1\times {10}^7\times 3}\Rightarrow z=2$