I think it would be solubility but I’m not sure
So potassium<span> is </span>more<span> reactive </span>than<span> lithium because the outer electron of a </span>potassium<span> atom is </span>further<span> from its nucleus </span>than<span> the outer electron of a lithium atom.</span>
Answer: The Answer is C.
Explanation: The Nucleus only makes up less than .01% of the volume of the Atom. The Nucleus does contain more than 99.9% of the mass of the Atom. I hope that this helps you! Good luck!