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🧪 Chemistry  ·  Chemical Bonding and Molecular Structure  ·  NEET & JEE

In which molecule does back-bonding (pi donation from F to empty p of central atom) significantly occur?

Answer: BF 3.

  • A BF<sub>3</sub>
  • B BCl<sub>3</sub>
  • C BI<sub>3</sub>
  • D BBr<sub>3</sub>

Correct answer: A. BF<sub>3</sub>

Explanation: In BF<sub>3</sub>, fluorine's lone pairs donate into boron's empty 2p orbital (p-pi back-bonding); this is strongest with F due to good orbital size match.

Linear180 deg, e.g. CO2Trigonal Planar120 deg, e.g. BF3Tetrahedral109.5 deg, e.g. CH4Trigonal Bipyramidale.g. PCl5Octahedrale.g. SF6

VSEPR theory predicts molecular shape from the number of bonding and lone electron pairs around the central atom.

Concept context

Understand how atoms join to form molecules. Covers ionic and covalent bonding, VSEPR theory, hybridization (sp, sp², sp³), molecular orbital theory, bond polarity, and intermolecular forces like hydrogen bonding.

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