Organic Chemistry- Substances only found in living organisms.
Physical Chemistry- Structure of physical compounds and the amount of energy they have.
Inorganic Chemistry- Study of carbon containing compounds.
Use a magnet to separate the iron from the sand.
Those would be called indicators , simply google them and you should find many. I'll leave some examples "bromophenol blue" "Methyl red" and "phenol red".
That is false because aluminum melts at 2,470C
