Question

Which one has the highest boiling point?
(A) $He$
(B) $Ne$
(C) $Kr$
(D) $Xe$

Answer 1

When an atom joins together in a definite ratio to form a molecule. Different molecules have different shapes and properties. Different types of force of attraction occurs between the molecules.

Complete step by step answer:
When molecules are formed and in molecule’s different types of attraction occur. This force of attraction in between molecules totally depends on how much distance occurs between the molecules.
This type of force of attraction also known as van der waals forces. This type of force arises due to fluctuation and nucleus shift one side and electron clouds shift another side. The nucleus side temporarily positive charge arises and electron clouds side arise negative charge so two poles are created one is positive pole and other is negative pole this is known as dipole. This dipole arises in non-polar molecules.
When a dipole molecule and polar molecules come closer to each other than the positive pole of dipole attracts towards negative charge of polar molecules. And the negative pole of the dipole attracts towards the positive end of polar molecules. So this type of attraction is known as dipole-polar attraction.
When this type of force of attraction occurs between two dipole molecules then this type of force of attraction is known as dipole-dipole attraction.
The strength of van der waal’s forces increases when the molecular mass of an element increases, the molecular mass of element increases then the boiling point of a molecule also increases. When we go down the group the atomic mass of elements increases and in given options xenon element $\left( {Xe} \right)$ has the highest boiling point.
Hence option D is the correct option.

Note:
Vander waals forces are very weak forces in nature as compared to ionic bond and covalent bond.
These forces are totally independent of temperature.
These forces occur when distance between molecules is very less.