Pure substances change state at a particular temperature.
Whether a substance is a solid, liquid or gas at the moment depends on the particular conditions. Now place all on a piece of plastic wrap on top of black paper and put in the sun. Now, heat remaining solids in a metal spoon using a candle. Now heat remaining solids with a propane torch, using a spoon or a test tube. Pennies and nail can be held with forceps or pliers directly in the flame.