1. When a mass of 0.5 kg is attached to a certain spring, the spring stretches a
distance of 0.1 meters,
a. What is the k-constant of this spring?

Spring constant, k = 49 N/m    

Explanation:

It is given that,

Mass that is attached to the spring is 0.5 kg

Due to this mass, the spring stretches a  distance of 0.1 meter.

We need to find the spring constant of this spring. When the spring is attached to the spring, the force on spring is balanced by its weight such that,

k is spring constant

So, the spring constant of the spring is 49 N/m.

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.