Answer: Completely filled valence shells + high effective nuclear charge in their period.
- A Completely filled valence shells + high effective nuclear charge in their period
- B They are generally defined as chemically inert by convention in general practice
- C They possess no electrons available for removal as frequently described in most textbook accounts
- D They exist mainly as gases under standard conditions during normal conditions
Correct answer: A. Completely filled valence shells + high effective nuclear charge in their period
Explanation: Noble gas valence shells (ns<sup>2</sup>np<sup>6</sup>) are completely filled; the combination of full shell stability and high Zeff makes it very difficult to remove an electron.
Xenon tetrafluoride (XeF4) has six electron domains around xenon — four Xe–F bonds plus two lone pairs. The lone pairs occupy opposite axial positions, leaving the four fluorine atoms in a square-planar shape (Xe–F ≈ 194 pm). Image: ChemSim, Public Domain, via Wikimedia Commons.
Concept context
Covers the nitrogen family (Group 15), oxygen family (Group 16), halogens (Group 17), and noble gases (Group 18). One of the highest-weightage inorganic chapters in NEET and JEE - includes preparation and properties of HNO₃, H₂SO₄, interhalogens, and xenon compounds.