Write the significance/applications of dipole moment.

(N/A) $1$. Determining the polarity of a bond: As $\mu = q \times d$,a greater magnitude of dipole moment indicates higher bond polarity. For a polar bond in an $A-B$ type molecule,the order is $HF > HCl > HBr > HI$. If $\mu = 0$,the molecule is non-polar (e.g.,$O_2, N_2, F_2, Cl_2, Br_2, I_2, H_2$).
$2$. Determining the shape (symmetry) of a molecule: Molecules like $BeF_2, CO_2, BeCl_2$ have $\mu = 0$ and are linear. Molecules like $H_2O, SO_2$ have $\mu \neq 0$ and are angular. Similarly,$BF_3, CH_4, CCl_4$ are non-polar,while $NF_3, NH_3, CH_3Cl$ are polar.
$3$. Calculation of ionic or covalent character: Ionic character is proportional to the difference in electronegativity. In $HI, HBr, HCl, HF$,the ionic character increases.
$4$. Distinguishing between cis and trans isomers: For cis isomers,$\mu \neq 0$,whereas for trans isomers,$\mu = 0$.
$5$. Distinguishing between ortho,meta,and para isomers: For para isomers,$\mu = 0$,and the dipole moment of ortho isomers is generally greater than that of meta isomers.