Which of the following contains atleast one lone pair in all of its halides?

Which of the following contains atleast one lone pair in all of its halides?
  1. $\mathrm{Xe}$
  2. $\mathrm{Se}$
  3. $\mathrm{Cl}$
  4. $\mathrm{N}$

Solution

To solve the question "Which of the following has at least one lone pair in all of its halides?" we will analyze the halides of each given element: Xenon, Selenium, Chlorine, and Phosphorus.
1. Identify the Elements and Their Halides:
- Xenon (Xe): Common halides include XeF2, XeF4, XeOF4, and XeO2F2.
- Selenlum (Se): Common halides include SeCl2 and SeCl6.
- Chlorine (CI): Chlorine itself is a halogen and does not form halides with other halogens.
- Phosphorus (P): Common halides include PCI3 and PCI5.
2. Analyze Xenon Halides:
- XeF2:
- Valence electrons = 8
- Bond pairs \(=2\) (with 2 fluorine atoms)
- Lone pairs = 8 - 2 = 6 (3 lone pairs)
- XeF4:
- Valence electrons \(=8\)
- Bond pairs = 4 (with 4 flucrine atoms)
- Lone pairs = 8-4 = 4 (2 lone pairs)
- XeOf4:
- Valence electrons = 8
- Bond pairs = 5 (4 with fluorine and 1 with oxygen)
- Lone pairs - 8 - 5 = 3 (1 lone pair)
- XeO2F2:
- Valence electrons = 8
- Bond pairs \(=4\) (2 with oxygen and 2 with fluorine)
- Lone pairs = 8 - \(4=4\) (1 lone pair)
- Conclusion for Xenon: All halides have at least one lone pair,
3. Analyze Selenium Halides:
- SeCl2:
- Valence electrons = 6
- Bond pairs \(=2\) (with 2 chlorine atoms)
- Lone pairs = 6 - 2 = 4 (2 lone pairs)
- Secle:
- Valence electrons = 6
- Bond pairs \(=6\) (with 6 chlorine atoms)
- Lone pairs \(=6\) - \(6=0\) (0 lone pairs)
- Conclusion for Selenium: SeCle has no lone pairs, so it does not satisfy the condition.
4. Analyze Chlorine Halides:
- Chlorine does not form halides with other halogens (it is itself a halogen).
- Conclusion for Chlorine: No lone pairs can be analyzed as it does not form halides.
5. Analyze Phosphorus Halides:
- PCI3:
- Valence electrons \(=5\)
- Bond pairs \(=3\) (with 3 chlorine atoms)
- Lone pairs = 5 - 3 = 2 (1 lone pair)
- PCIS:
- Valence electrons = 5
- Bond pairs \(=5\) (with 5 chlorine atoms)
- Lone pairs = 5 - 5 = 0 (0 lone pairs)
- Conclusion for Phosphorus: PCI5 has no lone pairs, so it does not satisfy the condition.
6. Final Conclusion:
- The only element that has at least one lone pair in all of its halides is Xenon (Xe).
Answer:
The correct option is Xenon (Option A).

Asked in: NEET 2016 (Phase 1)

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