Question

Noble gases have low boiling point because:
a.) Weak intermolecular force
b.) Strong intermolecular force
c.) Cannot withstand heat
d.) Both A and C

Answer 1

Hint: To answer this question, we must recall the properties of noble gases we have already learnt. We must also realize beforehand that boiling point and intermolecular forces have an inverse relation.

Complete step by step solution:
We know that the noble gases (Group 18) are placed at the far right of the periodic table and are referred to as the "inert gases" due to the fact that they have completely filled valence shells (octets) which makes them extremely nonreactive.
The size of the atom is positively correlated to several properties of noble gases. As we move down the group, the atomic mass, boiling point, and atomic radii increases.
Overall, noble gases have weak interatomic forces since they do not have any requirement to form bonds with each other in order to attain stable configuration, and therefore very low boiling and melting points compared with elements of other groups.
Thus, the noble gases all have low boiling points and the boiling point increases going down the group. This is because the atoms become larger and the intermolecular forces between the atoms become stronger. Hence, more energy is needed to overcome these forces.
Hence, the correct answer is Option (A) Weak intermolecular forces.

Additional information:
If the gases are monatomic, that means the intermolecular forces will be extremely weak. The intermolecular forces, in this case London dispersion forces, depend on the size of molecules. This is also a major contributing factor for low melting and boiling point.

Note: Helium, at the top of group 18 is the element with the lowest boiling point. This is the reason why it is used in very low temperature cryogenics, particularly for maintaining superconductors