Which molecular property defines the location of electrons?

When lactate builds up in a runners muscles it causes a burning sensation what causes this to occur

Which best describes the nucleus of an atom a. it is where all of the particle s of the atom are located b. it is the negatively charged part of the atom c. it is where the electrons and the protons are located d. it is the part of the atom with the greatest mass

What's the waste product of electrons and pyruvate combining in fermentation?