Based on VSEPR model, match the xenon compounds given in List-I with the corresponding geometries and the number of lone pairs on xenon given in List-II and choose the correct option.
| List-I | List-II |
| (P) XeF2 | (1) Trigonal bipyramidal and two lone pair of electrons |
| (Q) XeF4 | (2) Tetrahedral and one lone pair of electrons |
| (R) XeO3 | (3) Octahedral and two lone pair of electrons |
| (S) XeO3F2 | (4) Trigonal bipyramidal and no lone pair of electrons |
| (5) Trigonal bipyramidal and three lone pair of electrons |
Correct Answer :
P-5, Q-3, R-2, S-4
Solution :
The correct option is P-5, Q-3, R-2, S-4.
To determine the correct match between the xenon compounds (List-I) and their corresponding electron geometries and number of lone pairs (List-II), we can use the Valence Shell Electron Pair Repulsion (VSEPR) model.
Xenon (Xe) is a noble gas with 8 valence electrons in its outermost shell. The steric number (SN), which determines the electron-pair geometry, is calculated as:
Let's analyze each compound step-by-step:
(P) XeF2 (Xenon difluoride):
- Fluorine (F) forms a single bond (monovalent).
- Number of bonding electrons = 2 (used for 2 Xe-F single bonds).
- Remaining valence electrons on Xe = 8 - 2 = 6 electrons (which form 3 lone pairs).
- Steric Number = 2 (-bonds) + 3 (lone pairs) = 5.
- For SN = 5, the electron-pair geometry is trigonal bipyramidal.
- Hence, XeF2 has a trigonal bipyramidal geometry with three lone pairs.
Match: P-5
(Q) XeF4 (Xenon tetrafluoride):
- Number of bonding electrons = 4 (used for 4 Xe-F single bonds).
- Remaining valence electrons on Xe = 8 - 4 = 4 electrons (which form 2 lone pairs).
- Steric Number = 4 (-bonds) + 2 (lone pairs) = 6.
- For SN = 6, the electron-pair geometry is octahedral.
- Hence, XeF4 has an octahedral geometry with two lone pairs.
Match: Q-3
(R) XeO3 (Xenon trioxide):
- Oxygen (O) forms double bonds (each oxygen atom forms 1 -bond and 1 -bond).
- Number of bonding electrons = 6 (2 electrons shared per oxygen atom for 3 double bonds).
- Remaining valence electrons on Xe = 8 - 6 = 2 electrons (which form 1 lone pair).
- Steric Number = 3 (-bonds) + 1 (lone pair) = 4.
- For SN = 4, the electron-pair geometry is tetrahedral.
- Hence, XeO3 has a tetrahedral geometry with one lone pair.
Match: R-2
(S) XeO3F2 (Xenon trioxide difluoride):
- Oxygen atoms form 3 double bonds (sharing 6 electrons).
- Fluorine atoms form 2 single bonds (sharing 2 electrons).
- Total bonding electrons = 6 + 2 = 8 electrons.
- Remaining valence electrons on Xe = 8 - 8 = 0 (no lone pairs).
- Steric Number = 5 (3 -bonds to oxygen + 2 -bonds to fluorine) + 0 (lone pairs) = 5.
- For SN = 5, the electron-pair geometry is trigonal bipyramidal.
- Hence, XeO3F2 has a trigonal bipyramidal geometry with no lone pairs.
Match: S-4
Combining the matches gives: P-5, Q-3, R-2, S-4.
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