You need to know the specific properties of water that contribute to Earth's suitability as an environment for life. These include:
cohesive behavior
ability to moderate temperature
expansion upon freezing
versatility as a solvent
hydrogen bonding and polarity
Water is essential for life. Its special properties make water the single most important molecule in plant life. Which of the following properties of water enables it to move from the roots to the leaves of plants?
A. Water expands as it freezes.
B. Water is an excellent solvent.
C. Water exhibits cohesive behavior.
D. Water is able to moderate temperature.
Large bodies of water, such as lakes and oceans, do not quickly fluctuate in temperature. What is the reason for this phenomenon?
A. Water is an acid.
B. Water is a versatile solvent.
C. Water has a high heat capacity.
D. Water acts as a buffer.
Why does ice stay at the top of oceans instead of sinking to the bottom?
A. Ice is colder than liquid water.
B. Ice is less dense than liquid water.
C. Ice is more dense than liquid water.
D. Ice is warmer than liquid water.
Water is often called the "universal solvent" because many substances can be dissolved in water. What property of water allows it to be such a versatile solvent?
A. purity
B. polarity and cohesion
C. high heat capacity
D. expansion upon freezing
Water has a much higher specific heat than most other covalent compounds. What do you
predict might happen if water had a low specific heat instead?
A. Flooding would occur and animals would be forced to migrate.
B. Harmful organisms living in water would reproduce at a rapid rate.
C. Organisms that are sensitive to changes in temperature would die.
D. Plants would not have enough water to effectively carry out photosynthesis.
Answers
Correct answer: C. Water exhibits cohesive behavior.
Cohesion means that water molecules are attracted to each other and attracted to other substances, such as the walls of the xylem of plants. The water molecules behave this way because they are polar.
Correct answer: C. Water has a high heat capacity.
Water can absorb a large amount of energy without a large rise in temperature. This is called heat capacity. As the sun shines on bodies of water, they absorb great amounts of its energy without a large fluctuation in temperature.
Correct answer: B. Ice is less dense than liquid water.
Ice actually has a very different structure than liquid water, in that the molecules align themselves in a regular lattice rather than more randomly as in the liquid form. It happens that the lattice arrangement allows water molecules to be more spread out than in a liquid, and, thus, ice is less dense than water.
Correct answer: B. polarity and cohesion
Water molecules are polar. This means that they have slight positive and negatively charged ends. Water molecules are attracted to a wide variety of molecules because of those charges and thus, acts as a solvent for a variety of compounds.
Correct answer: C. Organisms that are sensitive to changes in temperature would die.