Heavy elements emit characteristics X-ray when their electrons undergo transitions. Shown below are the wavelengths of x-rays emitted by some elements:
Element          Wavelength (Å)
Cr                     2.291
Fe                     1.937
Co                    1.790
Cu                    1.542
Mo                    0.7107 
Calculate the frequency of each X-ray emitted and use that data to predict the wavelength of the light emitted by zirconium. Hint: Plot the square root of ν versus the atomic number of the element.