Certain elements emit light of a specific wavelength when they are burned or heated in a non-luminous flame. Historically, chemists used such emission wavelengths to determine whether specific elements were present in a sample. Some characteristic wavelengths for a few of the elements are given in the following table:
Ag 328.1 nm Fe 372.0 nm
Au 267.6 nm K 404.7 nm
Ba 455.4 nm Mg 285.2 nm
Ca 422.7 nm Na 589.6 nm
Cu 324.8 nm Ni 341.5 nm
(c) When burned, a sample of an unknown substance is found to emit light of frequency 6.58 * 1014 s-1. Which of these elements is probably in the sample?