(N/A) The significance and applications of dipole moment $(\mu)$ are as follows:
$1$. Predicting Polarity: It is a measure of the polarity of a bond. $A$ molecule with a non-zero dipole moment is polar,while a molecule with a zero dipole moment is non-polar (e.g.,$H_2, O_2, CO_2$).
$2$. Determining Molecular Geometry: Dipole moment helps in predicting the shape of molecules. For example,$H_2O$ has a bent structure with $\mu = 1.84 \ D$,whereas $CO_2$ has a linear structure with $\mu = 0$.
$3$. Calculating Ionic Character: It is used to calculate the percentage ionic character of a covalent bond using the formula: $\text{Percentage ionic character} = (\frac{\mu_{obs}}{\mu_{calc}}) \times 100$,where $\mu_{obs}$ is the observed dipole moment and $\mu_{calc}$ is the calculated dipole moment assuming $100$% ionic character.
$4$. Distinguishing Isomers: It helps in distinguishing between cis and trans isomers. Generally,the cis-isomer has a higher dipole moment than the trans-isomer.