Question

Give reason oxygen is a gas but sulphur is a solid?

Answer 1

Hint- In order to deal with this question we will consider the intermolecular forces of molecule if intermolecular force is higher than it has strong covalent bond or it can be solid and if intermolecular force is weak then the molecule will be in the form of gas.

Complete answer:
Oxygen occurs in the form of ${O_2}$ molecule because of the $p\pi - p\pi $ bonding formed within its molecule. Due to this reason the intermolecular forces present in oxygen are weak van der Waals forces. The main reason behind this is the small size and high electron density in it which tends to repel the other oxygen ${O_2}$ molecules. As a result of these reasons oxygen exists as gas.
On the other hand, Sulphur does not form strong $S = S$ double bonds hence exists as ${S_8}$ held together by strong covalent bonds and exists as a polyatomic molecule, in which intermolecular forces are strong so, it exists as a solid.

Note- Intramolecular forces are those forces that hold atoms in a molecule together. Intermolecular forces are forces which exist among molecules. There are five types of intermolecular forces: dipole-ion forces, dipole-induced-ion forces, dipole-dipole forces, dipole-induced forces and dipole-induced forces. Intramolecular bonds have 3 types: covalent, ionic, and metallic. Covalent bond: A bond with which two atoms share a pair or pair of electrons. The strongest intermolecular force is hydrogen bonding. London dispersion forces are the weakest of the intermolecular forces.