(a) Based on the nature of intermolecular forces, classify the following solids: Silicon carbide, Argon
(b) ZnO turns yellow on heating. Why?
(c) What is meant by groups 12-16 compounds? Give an example.

(a) Based on the nature of intermolecular forces we can classify

Silicon carbide as a Covalent solid because it contains Covalent bonding

Argon as non-polar molecular solid because it contains London forces.

(b) On heating ZnO losses oxygen and get converted into Zn²⁺ ions. And turns yellow. This is due to metal excess defect.

The excess Zn²⁺ ions are trapped in interstitial sites and equal number of electrons are trapped in neighborhood. Due to presence of Electrons in interstitial void color is yellow.

(c) The solid materials prepared by combination of elements from group 12 and 16 are called group 12-16 compounds. Examples: ZnS