You are presented with the quiz "What can you add to a solid to lower its freezing point?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "adding salt to a solid decreases the freezing point of that solid" and "another name for salt is sodium". So, what's the best answer to the question?
OPT: [i] calcite [ii] energy [iii] heat [iv] sodium [v] boiling [vi] Solutions [vii] salinity [viii] Energy.
Answer:
[iv]