A student staying in a coastal region tests the drinking water and also the sea water 'With a circuit in which a part of the connecting wire is wound around a matchbox containing compass. He finds that the compass needle deflects more in the case of sea water. Can you explain the reason?

Sea water is a better conductor because it contains sodium and chloride ions in large amounts. These ions make the solution conducting and thus, sea water is considered better conductor than the drinking water which does not contain ions. The ions of drinking water are removed while removed while purifying it.