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

Which of the following is an exception to the octet rule by being electron-deficient?

Answer: BF 3.

  • A BF<sub>3</sub>
  • B PCl<sub>5</sub>
  • C SF<sub>6</sub>
  • D NO<sub>2</sub>

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

Explanation: BF<sub>3</sub> has only 6 electrons around boron (three bonding pairs); it is electron deficient (incomplete octet).

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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