What does Newton's first law of motion imply about an object in motion? A. It will tend to exert a friction force on the air around it.
B. It will tend to slow down until it comes to rest,
C. It will tend to remain at a constant velocity unless acted upon by a
force
D. It will tend to accelerate until it reaches the speed of light unless
acted upon by a force.

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.

snell's law

refractve index = sin incidence / sin refraction