As you run toward a source of sound, you perceive the frequency of that sound to

frequency is the speed of vibration and this determines the pitch of the sound. it is only useful or meaningful for musical sounds. where there is a strongly regular waveform. frequency is measured as the number of wave cycles that occur in one second. the unit that is being measured is (hz)

neither accurate nor precise.

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.