Which of the following describes a unique property of water that sustain marine life?

a. it freezes upward from the bottom unlike other liquids that freeze downward from the top.

b. it has a lower density in its solid state than it does in its liquid state.

c. it shows changes in density at temperatures above 4 °c.

d. it cools faster and heats up faster than most other liquids.

B

Explanation:

Since ice is less dense than water, it floats. This forms an ice cover sheet in cold regions such as in the poles. This insulates the water beneath from excessive heat loss hence preventing it from turning into ice too, This protects the marine life beneath. Also, water does not gain heat or loss it rapidly (due to its high heat capacity) hence offering a more or stable temperature range for marine life.

gravity causes stares to cluster i think so

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.