In an experiment the HYPOTHESIS is tested. The hypothesis is the assumption, that you make about something. Example would be, you believe (hypothesize) that the baking soda will react faster in vinegar than in water. You then test it out (or preform and experiment) to see if your hypothesis is correct or wrong.
Every action has an equal and opposite reaction. I would assume that the energy in the other direction would be an action.. though I'm not entirely sure. I hope it helps.
Discontinuous variable ;)
If there isn’t multiple choice I think it is the ones in the center ring (the closest ring to the center) of the atoms
