Solved: CHEMISTRY Question for NEET

NEET CHEMISTRYMedium

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

SF $_4$ , BrF $_5$

SF $_4$ , ClF $_3$

ClF $_3$ , XeF $_4$

XeF $_4$ , BrF $_5$

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.
Analyze SF $_4$ : Sulfur (Group 16) has 6 valence electrons. It forms 4 sigma bonds with Fluorine. Remaining electrons = $6 - 4 = 2$ . Thus, it has 1 lone pair .
Analyze BrF $_5$ : Bromine (Group 17) has 7 valence electrons. It forms 5 sigma bonds with Fluorine. Remaining electrons = $7 - 5 = 2$ . Thus, it has 1 lone pair .
Analyze ClF $_3$ : Chlorine (Group 17) has 7 valence electrons. It forms 3 sigma bonds with Fluorine. Remaining electrons = $7 - 3 = 4$ . Thus, it has 2 lone pairs .
Analyze XeF $_4$ : Xenon (Group 18) has 8 valence electrons. It forms 4 sigma bonds with Fluorine. Remaining electrons = $8 - 4 = 4$ . Thus, it has 2 lone pairs .
Conclusion: Both SF $_4$ and BrF $_5$ have exactly one lone pair on the central atom.

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