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NEET CHEMISTRYOrganic Chemistry – Some Basic Principles and Techniques Medium

Question

Which pair of the following compounds has one lone pair of electrons on the central atom?

A

SF4_4, BrF5_5

B

SF4_4, ClF3_3

C

ClF3_3, XeF4_4

D

XeF4_4, BrF5_5

Step-by-Step Solution

  1. Method: To find the number of lone pairs on the central atom, calculate the valence electrons remaining after bond formation. Lone Pairs = (Valence electrons of central atom - Valency of surrounding atoms) / 2.
  2. Analyze SF4_4: Sulfur (Group 16) has 6 valence electrons. It forms 4 sigma bonds with Fluorine. Remaining electrons = 6−4=26 - 4 = 2. Thus, it has 1 lone pair .
  3. Analyze BrF5_5: Bromine (Group 17) has 7 valence electrons. It forms 5 sigma bonds with Fluorine. Remaining electrons = 7−5=27 - 5 = 2. Thus, it has 1 lone pair .
  4. Analyze ClF3_3: Chlorine (Group 17) has 7 valence electrons. It forms 3 sigma bonds with Fluorine. Remaining electrons = 7−3=47 - 3 = 4. Thus, it has 2 lone pairs .
  5. Analyze XeF4_4: Xenon (Group 18) has 8 valence electrons. It forms 4 sigma bonds with Fluorine. Remaining electrons = 8−4=48 - 4 = 4. Thus, it has 2 lone pairs .
  6. Conclusion: Both SF4_4 and BrF5_5 have exactly one lone pair on the central atom.

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Organic Chemistry – Some Basic Principles and Techniques . Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

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