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Which element has a \mathrm{K}_\alpha line of wavelength \mathrm{ 1.785 \, \, \AA}

Option: 1

Copper


Option: 2

Cobalt


Option: 3

Sodium


Option: 4

Aluminium


Answers (1)

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We know that, \frac{1}{\lambda_{\mathrm{k}_\alpha}}=\mathrm{R}(\mathrm{Z}-1)^2\left(\frac{1}{1^2}-\frac{1}{2^2}\right)

                 (Z-1)^2=\frac{4}{3} \times \frac{1}{\lambda_{k_\alpha} R}=680

                 \begin{aligned} & (Z-1)=26 \\ & Z=27 \rightarrow \text { cobalt } \end{aligned}

 

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Rishi

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