Question

Which of the following molecules will not have a dipole moment?

• A. $C{H}_{3}Cl$
• B. trans $CHCl=CHCl$
• C. $C{H}_{2}C{l}_2$
• D. $CC{l}_2=C{H}_2$

Answer 1

The correct option is B trans $CHCl=CHCl$

In trans-$1,2$-dichloroethane, the dipole vectors of two $C-Cl$ bonds are equal in magnitude and opposite in direction. Hence, they cancel each other.
Similarly the dipole vectors of two $C-H$ bonds are equal in magnitude and opposite in direction. Hence, they cancel each other.
Thus the molecule has no net dipole moment.