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GATE 2023 CY – Question 55

Inorganic Chemistry · Main Group Elements: Shapes and structures of molecules using VSEPR postulates, Hydrides, halides, oxides, oxoacids, nitrides, sulfides - shapes and reactivity. Structure and bonding of boranes, carboranes, silicones, silicates, boron nitride, borazine and phosphazenes: electron counting in polyhedral boranes, isolobal analogy. Allotropes of carbon, phosphorus and sulfur. Industrial synthesis of compounds of main group elements such as NH3, H2SO4 and HNO3. Chemistry of noble gases and interhalogen compounds. Acid-base concepts and principles (Lewis, Brønsted, HSAB and acid-base catalysis). · 2 marks · Multiple select

Which statements about $XeF_2$ are correct?

  1. Its bonding is best explained by classical two-centre two-electron bonds
  2. Its bonding is best explained by a nonclassical three-centre four-electron bond
  3. It contains nine lone pairs of electrons
  4. Its point group is $D_{\infty h}$

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Correct answer: (B) Its bonding is best explained by a nonclassical three-centre four-electron bond; (C) It contains nine lone pairs of electrons; (D) Its point group is $D_{\infty h}$

Explanation

Linear XeF2 is described by a three-centre, four-electron bond across F–Xe–F. Xenon has three lone pairs and each fluorine has three, giving nine in total. Its linear centrosymmetric structure belongs to D∞h.

Thus **B, C, D** are true; localized classical two-centre bonds do not best describe the hypervalent bonding.