Why is the sky blue? Why does the moon appear in the daytime?
How much does the sky weigh?
How do airplanes stay in the air?
Why is water wet?
Why don't birds get electrocuted when they land on an electric wire?​

the sky is blue because of reflection of blue light of sea and ocean.

the moon appear in the daytime because light of sun is brighter than of moon

airplanes stay in the air by maintaining balance in air and gravity.

birds did not get electrocuted when they land on an electric wire because there body is non conductor.

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.