Chemical Bonding and Molecular Structure — JEE Advanced · 2019 · 27 May 2019 · Paper 1 Question with Solution

Each of the following options contains a set of four molecules. Identify the option(s) where all four molecules possess permanent dipole moment at room temperature.

(A) $BeCl_{2}, CO_{2}, BCl_{3}, CHCl_{3}$
(B) $SO_{2}, C_{6} H_{5} Cl, H_{2} Se, BrF_{5}$ ✓ Correct
(C) $BF_{3}, O_{3}, SF_{6}, XeF_{6}$
(D) $NO_{2}, NH_{3}, POCl_{3}, CH_{3} Cl$ ✓ Correct

Answer: (B), (D)

Solution

A molecule has a permanent dipole moment if it is asymmetric (non-zero vector sum of bond dipoles).

(1)

BeCl_{2}

(linear),

CO_{2}

(linear),

BCl_{3}

(trigonal planar) are all symmetric and nonpolar. Only

CHCl_{3}

is polar. NOT all four.

(2)

SO_{2}

(bent),

C_{6} H_{5} Cl

(substituted benzene),

H_{2} Se

(bent),

BrF_{5}

(square pyramidal) — all are polar. ALL four.

(3)

BF_{3}

(trigonal planar, nonpolar),

O_{3}

(bent, polar),

SF_{6}

(octahedral, nonpolar),

XeF_{6}

(distorted octahedral, polar). NOT all four.

(4)

NO_{2}

(bent),

NH_{3}

(pyramidal),

POCl_{3}

(tetrahedral with P=O, polar),

CH_{3} Cl

(tetrahedral, polar) — all are polar. ALL four.

Options (B) and (D) are correct.

JEE Advanced · 2019 · 27 May 2019 · Paper 1 · One or more correct options

JEE Advanced · 2019 · 27 May 2019 · Paper 1 · Chemical Bonding and Molecular Structure

Solution

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