How properties before and after a chemical reaction can be used to determine if a chemical reaction occurred

Ionic compounds are made of ions, and yet the overall charge of an ionic compound is neutral. why?

How does the presence of oxygen affect the chemical pathways used to extract energy from glucose?

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.