Question

Which of the following molecules has highest dipole moment ?

• A. $C{H}_{3}Cl$
• B. $C{H}_{2}C{l}_2$
• C. $CHC{l}_3$
• D. $CC{l}_4$

Answer 1

The correct option is A $C{H}_{3}Cl$

Dipole is a physical quantity. Methane has zero dipole moment. Replacement of one H- atoms by Cl atom increases the dipole moment. The increase in dipole moment is because the bond dipole moment of C - H bond and that of C-Cl bond reinforce each other. Replacement of another H atom by Cl increases the bond angle due to lone pair - lone pair repulsion between Cl- atoms. This reduces the dipole moment and introduces the third Cl - atom. So when fourth Cl - atom is introduced the molecule $\left(CC{l}_4\right)$ again becomes symmetrical and dipole moment reduces to zero.So, $C{H}_{3}Cl$ has highest dipole moment.