1. The mechanical energy of the pendulum at the highest point equals a. kinetic energy only.
b. kinetic energy x potential energy.
c. potential energy only.
d. zero.

c. potential energy only

Explanation:

at highest point the body will having some height and gravitational force will work on it.

since the velocity at highest point will be zero therefore there will no kinetic energy

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.