Big Time Huge Flame Test Question?

Question

so i missed a lab in grade 9 science because i went to Track.
anyways, i have to type up this lab and i have no clue about anything except that we had:

Lithium Nitrate
Sodium Nitrate
Potassium Nitrate
Barium Nitrate
Calcium Nitrate
Copper Nitrate
....and 2 unknown elements
to be exposed to a bunsen burner flame.

i know the colours produced by everything except the 2 unknown compounds. If you know what they might be (must be metal nitrates), please say so.

Also, i was given 4 questions:

1.what were the 2 unknown compounds and how did you decide what they were?

2. which metals were easy to identify?

3. Which metals were difficult to identify?

4. why were all of the compounds tested nitrates?

if you have any idea what the 2 unknown compunds were and any of the answers to the 4 questions could you please post!

Answer 1

Hi. Two that seem to be missing are rubidium nitrate and cæsium nitrate, if that is any help.

Answer 2

strontium nitrate
it produces white sparks.
I don't know the other one.