i agree... i carefully noticed that the question said IDENTIFY these compounds... not DISTINGUISH them...jacksdharma said:REASON FOR NOT DOING FLAME TEST:
The reason for not conducting the flame test is the mixing of the cation and anions. Normally when conducting a flame test you use a variety of metallic ions which have a common salt base such as Cl. This allows you to distinguish between the metals as the Cl remains constant in all of them. Since the compounds had a differing anion, NO3, Cl, CO3, there was no way of identifying them correctly.
if you use a flame test on a solution of sodium carbonate, you can deduce that it contains sodium, but not carbonate.