posted by mysterychicken on .
27. Amorphous solids have crystal structures.- F?
32. Pure, crystalline solids freeze and melt at the same temperature.- F
34. Water expands as it freezes.- T
34. Bad question. The answer depends on what you mean "as it freezes". Water has a maximum density at 4C, and it lessens density as it cools or heats. Lessen density means expand.
However, water at 12C is considerably less dense than ice, so if you are comparing those two temps, then water contracts "as it freezes". Look at the graph.
You teacher probably wants "true" there.
32. The melting point of anything is the same as the freezing point. Student's always think they are different but they are the same. If water freezes at 32 F it must also melt at 32 F. So water at 32 F does what? freeze or melt? It depends upon which way the heat is going. If you have it in a freezer it will freeze. If you have it on a table at room temperature, it will melt.