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 
For each element, calculate the frequency (Hz) of the X-ray emitted.

• A. Cr: 1.310×10¹⁸ Hz; Fe: 1.549×10¹⁸ Hz; Co: 1.676×10¹⁸ Hz; Cu: 1.946×10¹⁸ Hz; Mo: 4.221×10¹⁸ Hz
• B. Cr: 2.219×10¹⁸ Hz; Fe: 2.412×10¹⁸ Hz; Co: 1.775×10¹⁸ Hz; Cu: 1.466×10¹⁸ Hz; Mo: 4.221×10¹⁷ Hz
• C. Cr: 1.418×10¹⁸ Hz; Fe: 1.542×10¹⁸ Hz; Co: 1.766×10¹⁸ Hz; Cu: 1.496×10¹⁸ Hz; Mo: 1.364×10¹⁸ Hz
• D. Cr: 2.219×10¹⁸ Hz; Fe: 1.459×10¹⁸ Hz; Co: 1.787×10¹⁸ Hz; Cu: 1.654×10¹⁸ Hz; Mo: 1.364×10¹⁷ Hz

Answer: (A)