Apparatus: Bunsen burner, copper gauze, metal plate, etc.
Chemicals : Ethanol, acetic acid, naphthalene
Procedure: Place one of the above chemicals (3-4 drops or a pinch) on clean copper gauze at room temperature, hold it on a blue flame of the Bunsen burner and observe.
Is smoke/soot seen to form due to combustion? Hold the metal plate on the flame when the substance is undergoing combustion. Does any diposit get collected on the plate? Which colour? Repeat the same procedure using other chemicals from the above list.

Explanation

Ethanol and acetic acid are saturated compounds. They burn with clean blue flame without producing smoke. However, naphthalene is an unsaturated compound and burns with a yellow flame and releases black soot/smoke. The black soot gets deposited on the metal plate only in case of naphthalene.