Question

The solubility of noble gases in water shows the order:
A. $He > Ar > Kr > Ne > Xe$
B. $He > Ne > Ar > Kr > Xe$
C. $Xe > Kr > Ar > Ne > He$
D. $Xe > Ar > Ne > Kr > He$

Answer 1

We need the various factors which contribute to the solubility of noble gases. As the name suggests, noble gases mean the gases which do not react with anything hence also known as inert gases. These gases have 2, 8, 8 electrons in their outer shell with a complete octet hence very stable and very inert. This series of elements consist of helium, neon, argon, krypton, xenon, and radon with helium at the top of the group 18 and radon at the bottom.

Complete step by step answer:
We need to know that the noble gases are non-polar elements but they can still dissolve but to a very less extent. We first need to study the trend of size of atoms as we move down the group in a periodic table. Atomic size increases as we go down the group.
We must have to remember that solubility is the property to dissociate in water which depends on dipole-dipole interaction. Noble gases are soluble in water due to dipole induced dipole interaction. Dipole-dipole forces are attractive forces between the positive end of one polar molecule and the negative end of another polar molecule. With the increase in size, the dipole-dipole interaction decreases hence becoming more soluble in water.
Keeping the above criteria in mind, we can conclude that He is the least soluble in water due to a small atomic size and hence stronger dipole-dipole interactions and Radon is the most soluble noble gas.
Therefore, for the given noble gases, the order of solubility is $Xe > Kr > Ar > Ne > He$ .

So, the correct answer is Option C.

Note: We must be noted that noble gases are used in conditions where a stable element is needed to maintain a safe and constant environment. The outer shell of valence electrons is considered to be full of noble gases, giving them little tendency to participate in chemical reactions and hence inert. Another term for solubility of these noble gases is polarizability that is the tendency to polarize.