Critical thinking and applications: identify the unknown sample. summarize the process that produces the colors seen in the flame test. what is the relationship between the colors you saw from the flame test and the lines on the electromagnetic spectrum? how do you think metallic salts are used in fireworks? explain why a metallic ion produces a characteristic color in a flame test, regardless of the compound used as the source of the ion. 6. based on your results and observations, would this method be practical to determine metals in a mixture? explain. 7. list the following ions in increasing order of the energy of the light emitted: cu+2, na+, li+, ca+2