Answer:
One part of the evidence that the color of the flame created is from the metal ion and not from the chemical is that not any of the flames with dissimilar metals had a similar color (for each metal had its flame color). Even if most of the metals tested had chloride, the colors of the flames were all dissimilar. The two flames that both had copper (one had copper (II) chloride and the other had copper (II) sulfate) were exactly close in color. The one was green-blue, and the other was a bright green. This displays that they were nearly the same, and the minor difference could be credited to error.