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Looking at the information given in the description, the experiment is testing for the effects of the different salts on the growth of the plants.
This means that the type of salt is the independent variable, or the variable being manipulated and tested.
To ensure fair results, some parts of the experiment would need to be kept the same, which is the control. The only answer choice that makes sense in this instance is A. water.
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.