If the $\;K_{\alpha}\;$ radiation of $\;M_{0}\;(Z=42)\;$ has a wavelength of $\;0.71 A^{0}\;$ , than the wavelength of corresponding radiation of Cu , i. e , $\;K_{\alpha}$ for Cu $\;(z=29)\;$ assuming $\;\sigma=1\;$ .

Question

$(a)\;1.5A^{0}\qquad(b)\;2.6A^{0}\qquad(c)\;3.6A^{0}\qquad(d)\;4.2A^{0}$