Consider the following compounds in the liquid form : $\mathrm{O}_{2}, \mathrm{HF}, \mathrm{H}_{2} \mathrm{O}, \mathrm{NH}_{3}, \mathrm{H}_{2} \mathrm{O}_{2}, \mathrm{CCl}_{4}, \mathrm{CHCl}_{3}, \mathrm{C}_{6} \mathrm{H}_{6}, \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{Cl}$. When a charged comb is brought near their flowing stream, how many of them show deflection as per the following figure?

JEE Advanced · 2020 · 27 Sep 2020 · Paper 2 · Chemical Bonding and Molecular Structure

Consider the following compounds in the liquid form :

O_{2}, HF, H_{2} O, NH_{3}, H_{2} O_{2}, CCl_{4}, CHCl_{3}, C_{6} H_{6}, C_{6} H_{5} Cl

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When a charged comb is brought near their flowing stream, how many of them show deflection as per the following figure?

Answer: 6

Solution

When a charged comb is brought near a flowing liquid stream, polar molecules are attracted/deflected due to their permanent dipole moment.

Polar molecules (will deflect):

$HF$ — highly polar H-F bond
$H_{2} O$ — bent structure, polar
$NH_{3}$ — pyramidal structure, polar
$H_{2} O_{2}$ — non-linear structure, polar
$CHCl_{3}$ — tetrahedral with net dipole
$C_{6} H_{5} Cl$ — chlorobenzene, polar

Non-polar molecules (no deflection):

$O_{2}$ — homonuclear diatomic
$CCl_{4}$ — symmetrical tetrahedral, dipoles cancel
$C_{6} H_{6}$ — benzene, symmetrical

Total polar molecules = 6

JEE Advanced · 2020 · 27 Sep 2020 · Paper 2 · Integer answer

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JEE Advanced · 2020 · 27 Sep 2020 · Paper 2 · Chemical Bonding and Molecular Structure

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