Which colligative property is primarily responsible for salt being used to melt ice on roads?

The property that is primarily responsible for salt being used to melt ice on roads is freezing point depression. When salt is added to ice, it dissolves and the resulting solution has a lower freezing point than pure water. This means that the temperature at which water freezes is decreased, allowing the ice to melt even when environmental temperatures are below 0°C.

Salt, or sodium chloride, dissociates into its constituent ions in solution, which interferes with the ability of water molecules to form the solid ice structure. The presence of these ions disrupts the arrangement required for water to freeze, thereby requiring a lower temperature to achieve the solid state. This colligative property effectively keeps the water in liquid form on the road, preventing the formation of ice, which can be beneficial for safety and traction during winter conditions.