Question

Which element out of He, Ar, Kr, and Xe forms the least number of compounds?
A.Kr
B.Xe
C.Ar
D.He

Answer 1

Hint: Periodic table is a great source of information about the elements and their relation to each other. Changes of different periodic properties. Also, this helps to predict the properties of the elements even if they are not discovered. Inert gases are from group 18. Which is on the extreme right side of the periodic table.

Complete step by step answer:
To answer this question the periodic properties of the elements from the different groups should be known. The periodic properties have opposite trends between left to right and top to bottom. The elements in periodic tables are arranged in a way that every element of each group shows similar physical characteristics and chemical characteristics.
Among the inert gases, helium cannot form any compound. There is no compound of helium found yet. This is because helium has an electronic configuration of $1{s^2}$ . Due to the small size of helium, it has high ionization enthalpy. As well as the highest positive electron gain enthalpy. So due to these reasons, the reactivity of helium is least

So, the correct option is D.

Note:Xenon is an inert gas. Its electronic configuration is $[Kr]4{d^{10}}5{s^2}5{p^6}$ . All orbitals that are filled have paired electrons. Xenon can combine with an even number of F atoms to form $Xe{F_2}$ , $Xe{F_4}$ and $Xe{F_6}$ . This is because the promotion of 1, 2, or 3 electrons from the 5p filled orbitals to 5d vacant orbitals will give rise to $2,4,6$half-filled orbitals. But it cannot combine with an odd number of F –atoms. Thus, the formation of $Xe{F_3}$ and $Xe{F_5}$ is not possible.