The ease of liquification of noble gases decreases in the order: (a) \(\mathrm{He}>\mathrm{Ne}>\mathrm{Ar}>\mathrm{Kr}>\mathrm{Xe}\) (b) \(\mathrm{Xe}>\mathrm{Kr}>\mathrm{Ar}>\mathrm{Ne}>\mathrm{He}\) (c) \(\mathrm{Xe}>\mathrm{He}>\mathrm{Kr}>\mathrm{Ar}<\mathrm{Ne}\) (d) \(\mathrm{Xe}>\mathrm{Ar}>\mathrm{Kr}>\mathrm{Ne}>\mathrm{He}\)

Noble gases, which occupy Group 18 of the periodic table, are well-known for their low reactivity. This characteristic is due to their complete valence electron shells, which make them resistant to forming chemical bonds. As a result of this stability, they are often found in a gaseous state under standard conditions of temperature and pressure.

Their physical properties, such as color and odor, also reflect this inertness; they are colorless, odorless, and tasteless. However, when discussing the liquefaction of noble gases, one must pay attention to their atomic size, boiling points, and the van der Waals forces that influence these properties. These elements become easier to liquify as you move down the group, primarily due to increases in their atomic size.

Van der Waals forces are weak attractive forces between atoms or molecules that are very close together. They are a critical factor in the physical state of noble gases. These forces can be attributed to the electron distribution around atoms, which fluctuates and momentarily creates dipoles that induce corresponding dipoles in adjacent atoms.

For noble gases, these forces are particularly significant as they are the only type of intermolecular force acting between the atoms, given that noble gases don't form other types of bonds easily due to their full valence shells. These transient forces grow stronger as atomic size increases, because larger atoms have more electrons which can contribute to the polarity and, consequently, the strength of the interactions.

When looking at noble gases, there's a direct correlation between atomic size and boiling point. As the atomic size increases, the attractive forces between the atoms, primarily van der Waals forces, also increase. The larger surface area of bigger atoms allows for a greater area over which van der Waals forces can act.

This means that it takes more energy to overcome these forces during phase changes. Hence, the boiling point - the temperature at which the liquid phase changes into the gas phase - increases. This correlation plays a significant role in the ease of liquefaction. Larger atoms, with higher boiling points, will condense into a liquid at higher temperatures, making them easier to liquify under controlled conditions.

The periodic table is structured to display trends in properties of elements, one of which involves moving down a group. For noble gases, as you move down the group from helium (He) to xenon (Xe), there is an increase in atomic size, mass, and boiling point. These trends can be attributed to the increasing number of electron shells as heavier noble gases have more energy levels.

Understanding this trend is essential for predicting the ease of liquefaction among the noble gases. As mentioned earlier, their relative ease of transitioning to a liquid state coincides with these periodic table trends. Consequently, xenon (Xe), being the largest of the noble gases, will liquefy at a relatively higher temperature than helium (He), which is the smallest and therefore hardest to liquify.