'Stability of a crystal is reflected in the magnitude of its melting points. Comment. Collect melting points of solid water, ethyl alcohol, diethyl ether and methane from a data book. What can you say about the inter molecular forces between these molecules?

How will you distinguish between the following pairs of terms:
Hexagonal close-packing and cubic close-packing?

How will you distinguish between the following pairs of terms:
Crystal lattice and unit cell?

How will you distinguish between the following pairs of terms:
Tetrahedral void and octahedral void?

Explain the basis of similarities and differences between metallic and ionic crystals.

Explain Ionic solids are hard and brittle.