B for sure, considering iron oxide is just fancy for rust.
Answer is in the photo. I can't attach it here, but I uploaded it to a file hosting. link below! Good Luck!
tinyurl.com/wpazsebu
Answer:

Explanation:
Hello!
In this case, for the undergoing chemical reaction:

We evaluate the yielded moles of zinc hydroxide by each reactant as shown below:

In such a way, since the water yields a smaller amount of zinc hydroxide we conclude it is the limiting reactant so the maximum mass is computed below:

Because the water limits the yielded amount of zinc hydroxide.
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Answer:
it may be electron, atom or ions depend on the nature of the substance and the character of reaction
like :- particles per mole, coulombs per electron
dont use that link its bad