What evidence is there from your results that the characteristic color observed for each compound is due to the metal ion in each case, and not the non-metal anion? describe an additional test that could be done to confirm that the color is due to the metal ion?

One part of 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 the similar color (for each metal had its own 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.

The flames with distinct metals had the same hue is one piece of evidence indicating the color of the flame is caused by the metal ion and not by the chemical (for each metal had its own flame color).

Even though most of the metals examined included chloride, the flame colors were all different.

The two copper-containing flames :

This shows that they were almost identical, and the slight discrepancy may be attributed to human error.

Thus, the test was characteristic of the metal ion.

To learn more about the flame test, refer to the link:

link