Answer the question on basis of passage given below:
The noble gases have closed shell electronic configuration and are monatomic gases under normal conditions. The low boiling points of lighter noble gases are due to the weak dispersion forces between the atoms and the absence of other inter atomic interaction. The direct reaction of xenon with fluorine leads to a series of compounds with oxidation numbers +2, +4 and +6.
\(XeF_4\) reacts violently with water to give \(XeO_3\). The geometries of the compounds of xenon can be deduced considering the total number of electrons in the valence shell.
Structure of \(XeO_3\) is :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Pyramidal
The shape of a molecule follows from the number of bond pairs and lone pairs around the central atom (VSEPR theory). In \( \ce{XeO3} \) the xenon atom has 8 valence electrons. Six are used in the three Xe=O bonds and two remain as one lone pair.
So there are 3 bond pairs + 1 lone pair = 4 electron pairs around Xe: sp3 hybridisation. The four pairs point to the corners of a tetrahedron; with one corner taken by the lone pair, the molecule is trigonal pyramidal, like \( \ce{NH3} \).
\( \ce{XeO3} \) is formed by hydrolysis of \( \ce{XeF4} \), as the passage says, and of \( \ce{XeF6} \):
\( \ce{6XeF4 + 12H2O -> 4Xe + 2XeO3 + 24HF + 3O2} \)
\( \ce{XeF6 + 3H2O -> XeO3 + 6HF} \)
Why the other options are incorrect
Option (1) Linear — Incorrect. Linear is the shape of \( \ce{XeF2} \) (2 bond pairs + 3 lone pairs), not of \( \ce{XeO3} \).
Option (2) Planar — Incorrect. A planar shape needs three bond pairs and no lone pair (like \( \ce{BF3} \)); the lone pair on Xe pushes the three O atoms out of the plane.
Option (4) T- Shaped — Incorrect. A T-shape comes from 3 bond pairs + 2 lone pairs (like \( \ce{ClF3} \)); \( \ce{XeO3} \) has only one lone pair.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Xenon-oxygen Compounds
