Base your answer on the information below and on your knowledge of chemistry. Fireworks that contain metallic salts such as sodium, strontium, and barium can generate bright colors. A technician investigates what colors are produced by the metallic salts by performing flame tests. During a flame test, a metallic salt is heated in the flame of a gas burner. Each metallic salt emits a characteristic colored light in the flame. State how bright-line spectra viewed through a spectroscope can be used to identify the metal ions in the salts used in the flame tests.