Which rock layer is the newest and why?
a. supai group because it is middle layer b. kaibab limestone because it is top most layer c. hermit shale because it is oldest type of rock d. tapeats sandstone because it is bottom layer

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.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.