Answer:
I believe the answer is "b". "During the experiment, the scientist has only one element, or variable, that is changed to test the hypothesis."
Explanation:
I remember from last year but I'm not totally sure. Good luck!
Answer:
Cool air moves down while hot air rises
It is necessary to make a logical system for naming compounds because there are so many of them and thinking of arbitrary random names for each one and then later remembering them all would be impossible. Also, they need to be all recognized and standardized for global use so as to have everyone use the same system.
