Why does an electrolyte depress the freezing point of a solvent more than a nonelectrolyte

What type of reaction fuels the processes seen here?

About 3% of the water on earth is freshest. only about 40% of that freshwater is available for human use. why is so much freshwater unavailable for human use?

What is a substance? a. a physical property of matter b. a chemical property of matter c. an element or compound that cannot be physically separated d. characteristics used to tell the difference between mixtures