Final answer:
The substance that melts ice the fastest is typically a substance that lowers the freezing point of water, such as salt or calcium chloride.
Step-by-step explanation:
The substance that melts ice the fastest is typically a substance that lowers the freezing point of water, such as salt or calcium chloride. When these substances are added to ice, they dissolve in the water present on the surface of the ice and create a solution with a lower freezing point than pure water.
This means that the ice will start to melt at a lower temperature than 0 degrees Celsius. As a result, the ice melts faster when these substances are present.
For example, rock salt (NaCl) or calcium chloride (CaCl₂), or a mixture of the two, can be used to melt ice quickly on roads and sidewalks during winter.