Question

Which noble gas has least tendency to form compounds ?

• A. Ar
• B. He
• C. Kr
• D. Ne

Answer 1

The Correct Option is B

Noble gases, also known as Group 18 elements or inert gases, are characterized by their highly stable electronic configurations. These elements have a full valence shell, making them highly unreactive and less likely to form compounds with other elements.
Among the noble gases, Helium (He) is the least likely to form compounds. It has the lowest atomic number and consists of only two electrons, which completely fill its first energy level. With a full valence shell, Helium does not readily gain, lose, or share electrons with other elements to form compounds.
Therefore, Helium (He) has the least tendency to form compounds among the noble gases.

Answer 2

Correct answer: He 

Helium (He) has the least tendency to form compounds among all noble gases because:

• It has a completely filled 1s² orbital (duplet configuration), which is extremely stable.
• It has a very high ionization energy and zero electronegativity.
• It is small in size and has no vacant d-orbitals for bonding.

Other noble gases like Kr and Xe can form compounds (e.g., XeF₂, KrF₂) due to availability of d-orbitals.

Hence, He is the most inert and least reactive of all.

Answer 3

He has the least tendency to form compounds.

Explanation:

• The tendency of noble gases to form compounds is related to their ionization energy and electron affinity. Noble gases have very high ionization energies and very low (or slightly positive) electron affinities, making it energetically unfavorable to form chemical bonds.
• Helium (He) is the smallest noble gas, with only two electrons in its valence shell (1s²). This configuration is exceptionally stable.
• Helium has the highest ionization energy among the noble gases. This means it requires the most energy to remove an electron from helium, making it extremely unreactive.
• As you move down the group (Ne, Ar, Kr, Xe, Rn), the ionization energy decreases, and the electron affinity becomes slightly more favorable. This makes it easier for the heavier noble gases to form compounds (though still challenging). For instance, xenon forms several well-characterized compounds with fluorine and oxygen.

Therefore, the correct answer is:

He