If we put a few spoonfuls of salt in a glass of water, we will find that the water surface will not only rise but also fall. What is the reason for this?

First, the water molecules are connected by hydrogen bonds. When the salt is put into the water, it will dissolve. This is an ionization process. The main components of the salt are sodium chloride, ionized sodium ions and chloride ions, and ion bonds with water. – Its energy level is lower than that of hydrogen bonds, so the water molecules become more compact, resulting in a smaller volume, which is the water surface we see.