Chemical Bonding - Result Question 6
####6. Arrange the following compounds in order of increasing dipole moment, toluene (I), $m$-dichlorobenzene (II), $o$-dichlorobenzene (III), $p$-dichlorobenzene (IV)
(a) I $<$ IV $<$ II $<$ III
(b) IV $<$ I $<$ II $<$ III
(c) IV $<$ I $<$ III $<$ II
(d) IV $<$ II $<$ I $<$ III
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Answer:
Correct Answer: 6. (b)
Solution:
- $p$-dichlorobenzene is non-polar.
The two dipole vectors cancelling each other giving zero resultant dipole moment. o-dichlorobenzene has greater dipole moment than meta-isomer.
(o-dichlorobenzene) dipole vectors are at $60^{\circ}$ angle
( $m$-dichlorobenzene) dipole vectors are at $120^{\circ}$ angle Toluene is less polar than both ortho and para dichlorobenzene. Therefore, the increasing order of dipole moment is
$p$-dichlorobenzene (IV) $<$ toluene (I) $<m$-dichlorobenzene (II)
$<o$-dichlorobenzene (III)
