Read the passage, then answer the questions that follow. Preserving Biological Samples Biologists often need to save samples for long periods of time. One of the best ways to do this is to use flash freezing. Flash freezing is the process of freezing substances very rapidly. When specimens are frozen very rapidly, water does not have a chance to form crystals, and enzymes do not have time to degrade in the cells. This allows biologists to protect as much of the living structure as possible. Because flash freezing keeps cells in such good shape, frozen cells are often still alive after they are unfrozen. Biologists can choose different substances to use for flash-freezing samples. The table lists several compounds that might be used. What is the smallest unit of matter that makes up each compound in the table?