Perform the experiments arranging the apparatus as shown in figure.

Record your observations and identify what type of compounds sodium chloride and sugar are.

Salt solution such as sodium chloride (NaCl) conducts electric current because it has ions in it which freely move about in solution.

These ions are produced when sodium chloride dissolves in pure water to produce sodium ions (Na⁺) and chloride ions (Cl^–). Oxidation is loss of electrons. Reduction is gain of electrons. Both occur here.

When you insert the graphite electrodes of a conductivity tester in the salt solution, the positive sodium ions (cations) usually move to the negative electrode (cathode), while the negative chloride ions (anions) move to the positive electrode (anion). This movement of ions to opposite ends of the electrodes allow electric current to flow through the solution.

On the other hand, sugar solution does not conduct an electric current because sugar (C₁₂H₂₂O₁₁) dissolves in water to produce sugar molecules. These sugar molecules are usually neutral (not charged), and so are unable to move to the opposite ends of the electrodes like the ions. Sugar doesn’t dissociate into ions when it is mixed in water.

Galvanometer is a device which shows the direction of electric current in a circuit. So, in the case of salt solution, conduction of current occurs and galvanometer shows a deflection. In the case of sugar solution conduction doesn’t occur, hence galvanometer shows no deflection.

Salt is ionic in nature and sugar is covalent in nature. Generally, solutions of ionic compounds conduct electricity and solutions of covalent compounds don’t conduct electricity.