The Water Cycle

How much of the Earth's water is usable as a freshwater resource? a. 75% b. 3% c. 100% d. 25%

Nearly 50% of water sources in the United States are believed to be polluted.

What happens to water in the atmosphere as it rises? a. It evaporates. b. It condenses and forms clouds. c. It combines with other gases in the air. d. It is used up.

How does water enter the atmosphere? a. Liquid water evaporates from lakes when heated by the sun. b. Frozen water sublimates from ice and snow. c. Liquid water is lost from tree leaves during evapotranspiration. d. All of the above.

Why does the government not do more to regulate nonpoint source pollution? a. Nonpoint source pollution is less harmful to the environment, so it does not need to be regulated. b. Point source pollution is more common than nonpoint source pollution, so it is more regulated. c. Nonpoint source pollution is caused solely by animals, which are not possible to regulate. d. Nonpoint source pollution is difficult to regulate, because its source is difficult to track

What are the ways that water vapor can reenter the atmosphere? a. sublimation b. evaporation c. evapotranspiration d. all of the above

The water on the Earth today has been sustaining life for millions of years.

After population growth, what does the United Nations believe will be the greatest future global problem? a. lack of usable freshwater b. lack of arable land c. excessive levels of air pollution d. excessive water pollution

How does capillarity help sustain life? a. Plants use capillarity to move water from their roots to their leaves. b. Capillarity allows water to form droplets. c. Animals rely on capillarity to maintain their body temperatures. d. Water's capillarity allows many different substances to dissolve in water

What role do aquifers play in the water cycle? a. They store water in the ground. b. They transfer water to the air. c. They are the main source of water on Earth. d. They move water through capillarity.