Answer:
E. Gain of electrons
Explanation:
A reduction reaction is one part of the two concurrent reactions that take place in a redox (reduction-oxidation) reaction.
During reduction, an atom gains electrons from a donor atom, and it's oxidation number becomes smaller.
Option A is wrong because reduction does not increase oxidation state nor are neutrons involved
Option B is wrong because reduction is not a nuclear reaction (does not involve the nucleons)
Option C is wrong because reduction leads to reduction in oxidation state
Option D is wrong leads to a reduction in oxidation state when electrons are gained
Option E is correct because reduction involves gain of electrons
Answer: the mass number is 51.9961 u.
Explanation: Basically your looking for the mass number of a ATOM of chromium now if you where looking for chromium and not the atom it's self it would be a different number which is 52-54
A matter zoo maybe or a matter pool party. Idk I have a couple more ideas