Which would show an example of how physical changes are reversible? cutting a gold bar in two pieces and then putting the pieces next to each otherburning a match and then relighting itmelting tin and then cooling it into a moldcombining sodium and chlorine to make the new material of table salt?

Melting a tin and again moulding it as then there will a physical change from solid to liquid and again back to solid .. gold don't have low melting point which can't be achieved by match sticks.. and mixing both sodium and chlorine is totally a chemical change as they form new compound

stands for electromotive force and it is measured in volts. despite its name, it is not actually the force in the sense of being a "pushing" or "pulling" (not measured in newtons).an equation that relates emf,  ℰ,  to a battery's terminal voltage, v, current, i, and internal resistance, r, is    ℰ = v + irin this case, the emf can be interpreted as a voltage—a difference in electric potential.i would not say that it would be considered an energy. if emf can be defined as the energy/work per a unit charge from a battery or other electric source, then it is not strictly energy.

Ithink it is a. but i'm not 100 percent sure.