Why does dissolved salt in water conduct electricity, but sugar does not?
Dissolved salt in water conducts electricity because salt is an ionic compound. In the solid state, its ions are held in fixed positions, but when dissolved in water, the ions become free to move and conduct electricity.
In contrast, sugar is a covalent compound. Although sugar is soluble in water, it does not provide ions in the solution. Since there are no free-moving ions to carry the electric charge, a sugar solution does not conduct electricity.
Explanation
The textbook states that ionic compounds like sodium chloride (salt) conduct electricity when dissolved in water because their ions are free to move. Conversely, covalent compounds like sugar dissolve in water but do not provide ions in solution, which is why they fail to conduct electricity.