D. one year
7. which of the following is not a characteristic of topsoil?
a. it develops very slowly and is the most utilized part of soil
b. it makes up the top two to eight inches of soil
c. it is the most fertile part of the land for growing plants
d. it develops very quickly and is the most utilized part of soil

biology is the study of life. it is the study of living organism.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.