What must be true for a spontaneous reaction in an electrochemical cell? The overall cell potential must be positive.
The overall cell potential must be negative.
The cathode's standard reduction potential must be positive.
The cathode's standard reduction potential must be negative.

Which of the following observations indicates that there is a small, dense, positively charged part in the center of an atom? some uncharged particles are scattered by a gold foil. all uncharged particles are attracted towards a gold foil. all positively charged particles pass straight through a gold foil. some positively charged particles bounce back from a gold foil.