On heating NaBr with concentrated sulphuric acid gives brown colour bromine vapours.
On heating NaNO3 with concentrated sulphuric acid will release a brown colour NO2 gas
On heating I− with concentrated sulphuric acid gives a dark purple colour.
On heating with concentrated sulphuric acid with CaF2 does not give any colour because it produces colourless hydrogen fluoride.Molar mass of CaF2 is 78.07g/mol