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

Isoelectronic species have the same number of electrons AND identical bond properties. Which pair is isoelectronic?

Answer: CO and N 2 (both have 14 electrons and triple bonds).

  • A CO and N<sub>2</sub> (both have 14 electrons and triple bonds)
  • B CO<sub>2</sub> and NO<sub>2</sub>, despite differing electron counts and bond orders
  • C H<sub>2</sub>O and H<sub>2</sub>S, despite sulfur's much larger atomic radius
  • D NaCl and KCl, despite potassium having more electrons than sodium

Correct answer: A. CO and N<sub>2</sub> (both have 14 electrons and triple bonds)

Explanation: CO has 14 electrons (6+8) and N<sub>2</sub> also has 14 electrons (7+7); both have triple bonds and are isoelectronic.

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.

Read the full Chemical Bonding and Molecular Structure notes →