Question

Why are Non-polar molecular solids called as solids when they are either liquids or Gases?

Answer 1

As we know that matters are divided into three types. There are solids, liquids and gas. Solids are divided into types. They are crystalline and amorphous. The crystalline is further divided into ionic solids, covalent solids, molecular solids and metallic solids. In crystalline solid, the basic repeating structural unit is called a unit cell.

Complete answer:
We have to know that the molecular solids are further classified as three types. These types depend on the bond in the molecules in front of solid. These molecular solids are due to the weak van der Waals forces. Polar molecular solids, non-polar molecular solids and hydrogen bonded molecular solids are the types of molecular solids.
Ice, glucose and urea are examples of hydrogen bonded molecular solids due to the hydrogen bonded in the molecular solids.
Naphthalene and anthracene are examples of polar molecular solids is due to the polar covalent bond in the molecular solids
Solid carbon monoxide and solid ammonia are examples of non-polar molecular solids due to the non-polar covalent bond in the molecular solids.
Non-polar molecular solids are held by non-polar covalent bonds, dipole-dipole interaction, weak dispersion force and London force in the molecules, because of weak force these are naturally liquids or gases. These do not have any solid property. Example non-polar molecular solids are insulators in nature but solids are good conductors of heat and electricity.

Note:
We have to know that there are seven types of primitive crystal system. There are cubic, tetragonal, orthorhombic, hexagonal, monoclinic, triclinic and rhombohedral. This classification of crystals is based on the crystallographic nature of angles, unit cells, primitive lattice and axes. These cubic crystals are further divided into three types. There are simple cubic crystals, face centered cubic crystals and body centered cubic crystals. This classification is based on the atoms arrangement in the cubic structure in the unit cell.