This is what occurs when matter transistions between soild, liquid, and gas

Hint: 11 letters

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

that's what i got you can count the number of atoms

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.