Question

The dipole moments of $o,p$ and m - dichlorobenzene will be in the order:

• A. $o>p>m$
• B. $p>o>m$
• C. $m>o>p$
• D. $o>m>p$

Answer 1

The correct option is D $o>m>p$

The magnitude of net resultant dipole moments of two dipole moment vectors (${\mu }_1$ and ${\mu }_2$ ) is given by,

${\mu }_{net}=\sqrt{({\mu }_1^2+{\mu }_2^2+2{\mu }_1{\mu }_{2}cos\theta )}$

The magnitude of net dipole moments depends on the angle between the two moments. In the para form, the angle between the two moments is ${180}^o$ and $cos{180}^o=-1$. Thus, it has the least dipole moment (Zero).
Again, among the ortho and the meta form, meta form has a greater angle between the two moments. Thus, it has a lower dipole moment compared to the ortho form. Thus, the correct order is
$o>m>p$