Answer:
Control is a group generall very important in an experiment because it allows you to eliminate and isolate these variables.
Answer: Classified as a theory.
Explanation: The dictionary definition of theory is a system of ideas that are used to logically explain something. It also says that they are also based off of something not entirely connected to the thing the theory is being made about.
Because the idea that the universe has expanded explains such a large number of observations, which in turn leads to more predictions and therefore more observations that support it, this becomes your system of ideas. Because this system was based off of the aforementioned observations in the first paragraph, this proves that it is best classified as a theory.
Answer:
She could time how long it takes for each amount of salt dissolves in the waters. (as well as keep each amount of salt the same if she was not doing that already.)
Explanation:
This way, she could observe which water is best for dissolving solvents and which is most affective in the shortest amount of time. If she was not timing how long it takes for salt to dissolve in different temperatures of water, then the experiment may as well have been useless unless there is somehow a different objective.
