Question

Volatile nature of halogens is because:
A. Halogen molecules are bonded by strong forces
B. Halogen molecules are bonded by electrostatic forces
C. The forces existing between the discrete molecules are only weak van der Waals forces
D. Halogen molecules are more reactive.

Answer 1

Hint: Halogens are group 17 in the periodic table, they are also called fluorine family, group 17 elements are salt-forming, hence called halogens (In Greek ‘halo’ means salt). The elements of the groups are Fluorine, chlorine, bromine, Iodine, astatine. And the volatile nature of an element denotes its lower boiling point.

Complete step-by-step answer:
From the given hint we can say that volatility of a substance is dependent on the boiling point of the molecule, and we know that boiling point depends on the intermolecular interaction, or the intermolecular force (the more strong the intermolecular force the higher is the boiling point).
The volatile nature of molecules means its ability to quickly convert into the gas phase at very low temperature or room temperature.
Halogens molecules are non-polar. E.g., ${\text{C}}{{\text{l}}_2}$, ${{\text{I}}_2}$ and they are bonded with weaker van der Waals force.
Van der Waals force is directly related to the atomic size, hence as the atomic size increases the energy required for the bond breakage also increases. This increases the boiling point of the halogen molecule.
Therefore, we can say weak van der Waals force is the reason for the volatile nature of halogens.

Hence, the correct answer is option (C) i.e., The forces existing between the discrete molecules are only weak van der Waals forces.

Note: The general English definition of the word volatile means how reactive is the substance, but in chemistry volatile refers to the ability of the substance to get converted into the gas-phase. E.g- Alcohol is a volatile liquid, while water is not.