What best explains the formula unit for a compound made from nitrogen and hydrogen?

nh4, because nitrogen needs four electrons, and each hydrogen needs one electron.
nh4, because nitrogen needs one electron, and each hydrogen needs four electrons.
nh3, because nitrogen forms a single bond with each hydrogen atom.
nh3, because nitrogen forms a triple bond with each hydrogen atom.

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The characteristics of two different types of reactions are shown below: reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of an element. which statement is true about the atoms of the elements that participate in the two reactions? their identity changes in both reaction a and reaction b. their identity changes in reaction a but not in reaction b. their identity changes in reaction b but not in reaction a. their identity remains the same in both reaction a and reaction b.