Which of the following compounds is non-polar?

Arrange the following molecules from most to least polar ($I$,$II$,$III$,$IV$,$V$ respectively): $CH_4$,$CF_2Cl_2$,$CF_2H_2$,$CCl_4$,$CCl_2H_2$.

Write the significance/applications of dipole moment.

$A$ covalent molecule $XY$ is found to have a dipole moment of $1.5 \times 10^{-29} \ C \cdot m$ and a bond length of $150 \ pm$. The percent ionic character of the bond will be (in $\%$)

Which of the following substances has the lowest dipole moment?

Which molecule has a zero dipole moment?