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Label each of the following phase changes as either exothermic or endothermic

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.

a corroding iron, if that's one of your choices

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)