Question

The forces acting between noble gas atoms are
A. Vander Waals forces
B. Ion-dipole forces
C. London dispersion forces
D. Magnetic forces

Answer 1

Hint: Noble gases hold the highest ionisation energies. As we progress through Group 18, the atomic radius and interatomic forces rise resulting in increased melting, boiling, and vaporisation enthalpies.

Complete Step by Step Solution:
Group 18 (noble gases) are present on the right-hand side of the periodic table. These are also called "inert gases" due to their filled valence shells thus making them incredibly non-reactive. These gases are not ions or permanent dipoles. These are non-polar atoms.

When an atom of a noble gas is nearer to another, there is an attraction between these molecules giving rise to London dispersion forces. Noble gases maintain the highest ionisation energies, the reason for their chemical stability. Due to this only weak forces exist between these gases.

Down the group, electrons get added to new subshells. So, the atomic size increases. As the atomic size of the atoms rises down the group, the electron clouds of these non-polar atoms become highly polarised leading to weak van der Waals forces among the atoms. The London dispersion force is a kind of the Van der Waals force. So, the forces acting between noble gas atoms are van der Waals forces.
So, option A is correct.

Note: Argon is the third noble gas and carries an atomic number of 18. This is depicted by the symbol Ar. It is noted to be the third most abundant gas in the Earth's atmosphere. When it is positioned in an electric field, it radiates a violet or lilac-colored light.