Wavelength of the $K_{\alpha}$ characteristic X-rays of iron and potassium are $1.93\times 10^{-8}$ are $3.737\times 10^{-8}cm$ respectively.What is the atomic number and name of the element for which characteristic $K_{\alpha}$ wavelength is $2.289\times 10^{-8}cm$.

Question

$\begin{array}{1 1}(a)\;22&(b)\;21\\(c)\;24&(d)\;23\end{array}$