The changes of state include melting, sublimation, evaporation, freezing, condensation, and deposition. All changes of state involve the transfer of energy. They are all the same but no matter what state it's in it's still water so it's physical.
When water changes state in the water cycle, the total number of water particles remains the same. The changes of state include melting, sublimation, evaporation, freezing, condensation, and deposition. All changes of state involve the transfer of energy.
Generally, when an acid and a base are added together in solution, a salt and water will form. This is known as an acid-base reaction. Therefore, the scientist may infer that she is working with an acid. (Acid + Base = H2O + Salt).