when a scientist is conducting research about all the plants and wildlife in the Mojave desert as well as the deserts resource such as water and soil the scientist is studying

The correct answer to the following question will be "An ecosystem".

Explanation:

So that the above seems to be the right answer.

the bal will not change its velocity.

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.