Apparatus: Metal spatula, burner, carbon electrodes, beaker, cell, lamp, press key, electrical wires, etc.
Chemicals: Samples of sodium chloride, potassium iodide and barium chloride, water.
Procedure: Observe the above samples. Place sample of one of the above salts on the spatula and heat it on the flame of the burner. Repeat the procedure using the other salts. As shown in the figure, assemble an electrolytic cell.

Assemble an electrolytic cell by using a beaker and connecting the carbon electrodes to the positive and negative terminal of the cell. Dip the electrodes in solution of any one of the salts. Do you see the lamp glowing? Check this with all the other salts as well.

Explanation

Samples of sodium chloride, potassium iodide and barium chloride do not readily melt on heating as they have high melting points. They give ions in their solutions. Due to these ions, their solutions become conductive. Hence, the lamp glows when electrodes are dipped in solutions of these salts