A demonstration of interference is done in class. A Slinky is stretched out from end to end. Three cups are placed on the ground, positioned just to the side of the Slinky™. Two pulses are introduced into each end at the same time. The pulses travel towards each other as shown in the overhead view diagram.

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.

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray