A for number 1 and C for number 2 im sorry i dont know the rest. :3
Independent variable would be salt since you can't change it in this experiment.
Answer: Kinetic Energy of the atoms also increases.
Explanation: We are given that the temperature of the gas increases.
Relation between kinetic energy and temperature follows:

where, K = Average Kinetic energy
R = Gas constant
T = Temperature
= Avogadro's number
As seen from the relation above, the Kinetic energy of the gas is directly proportional to the temperature, hence as the temperature increases, kinetic energy of the atom also increases.
I would say the head and heart because if you swim deep in the ocean you will feel pressure in your heart and head because the muscles in your body are closing in on them
hope i helped