The fact that ice is less dense than water is related to the fact that

The fact that atoms and molecules are more tightly packed, and do not move freely in ice, as it is in a solid form, vs water where they have the freedom to move is why Ice is more dense.

ice has a molecular structure that is an open framework held together by hydrogen bonds.

Explanation:

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).

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.