As the velocity of the sound source approaches the speed of sound, the wave fronts ahead of the object begin to appear as:

a-separately distinguishable waves

b-a single wave front
c-cylindrical
d-a cone shape shockwave.
Term 1

and when the velocity of the sound source exceeds the speed of sound, the wave fronts form:

Term 2

a-separately distinguishable waves

b-a single wave front
c-cylindrical
d-a cone shape shockwave.

The correct answer is D

shock waves

Explanation:

When a body approaches the speed of sound in the media, the waves it emits are getting closer and closer to each other, the envelope (sum) results in a kind of cylindrical cone that is similar to that formed in a supersonic process

The correct answer is D

When the speed of sound is exceeded, the body goes faster than the wave, so the so-called shock waves are formed.

  They carry a lot of 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.