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Problem 8 - Entrance Test

The hybridization of the central atom in the anion [ICl₄]⁻ is: (A) sp³ (B) sp³d (C) sp³d² (D) dsp²

Correct: C

ICl₄⁻ has iodine as the central atom. Iodine in ICl₄⁻ has 7 valence electrons; adding one for the negative charge gives 8 electrons. Four I–Cl bonds use 4 electrons, leaving 4 electrons as two lone pairs. The steric number is 6 (4 bonding pairs + 2 lone pairs), which corresponds to octahedral electron geometry. The molecular geometry is square planar. The hybridization is sp³d². Note: Some textbooks describe the bonding in hypervalent iodine compounds using d-orbital participation (sp³d²), while modern explanations invoke 3-center-4-electron bonds or s-p mixing. For JEE purposes, sp³d² is the expected answer. Answer: C.