Question

Which of the following molecules has the maximum dipole moment?
A) $C{O_2}$
B) $C{H_4}$
C) $N{H_3}$
D) $N{F_3}$

Answer 1

Hetero nuclear molecules are made up of different kind of atoms. More electronegative atom withdraws the shared pair of electrons, moves towards itself and acquires negative charges. The Other atom acquires the same amount of positive charges such as molecules having positive and negative charges separated by some distance (equal to their Bond length) from dipole and does possess dipole moment.

Complete step by step answer:
-Dipole moment of a molecule is the product of its net positive or negative charge and distance between the charges.
Dipole moment $\mu = e \times d$
Where $e$ the net is positive or net negative charge and is of the order of ${10^{ - 10}}esu$.
$d$ is the distance between the charges and is of the order of ${10^{ - 8}}cm$.
Thus, $\mu$ has a value of the order of ${10^{ - 10}}esu \times {10^{ - 8}}cm$. This quantity is called $debye(D)$ units.
-Dipole moment is a vector quantity having magnitude as well as direction. Magnitude of the dipole moment is indicated in $debye(D)$ units where $1D = {10^{ - 18}}esu.cm$
-Dipole moment in molecules having more than one polar bond= the dipole moment of molecules with more than one polar bond is equal to the resultant of dipole moments of all the individual bonds. It also depends upon the orientation in space of the bonds in a molecule.
-Dipole moment of substances-

Molecule	Nature of bond	Dipole moment	Nature of molecules
$C{O_2}$	Polar	$0$	Non-Polar
$C{H_4}$	Polar	$0$	Non-Polar
$N{H_3}$	Polar	$1.49D$	Polar
$N{F_3}$	Polar	$0.24D$	Polar

For example- Carbon dioxide and water are triatomic molecules having two polar bonds but dipole moment of carbon dioxide is zero whereas o water is $1.84D$. This difference in dipole moment is due to the difference in their structure.
-Carbon dioxide is a linear molecule in which the two carbon oxygen bonds are oriented at an angle of ${180^ \circ }$ with respect to each other. The dipole moment of each carbon oxygen bond is $2.3D$ but due to linear geometry of carbon dioxide the dipole moment of the two carbon oxygen bonds cancel each other and net dipole moment is zero.
Hence, Carbon dioxide is a nonpolar molecule.
The dipole moment of an ammonia molecule is $1.49D$, which is the resultant of three polar nitrogen hydrogen bonds oriented in space at an angle of ${107^ \circ }$.
Hence, option C is correct.

Additional information:
1. In CGS system the value of charges is $4.8 \times {10^{ - 10}}esu$ and distance $d$ is taken in centimetre $\left( {1{A^ \circ } = {{10}^{ - 8}}cm} \right)$. Thus, the product or the dipole moment is of the order of ${10^{ - 18}}esu.cm$ or $debye(D)$.
2. In SI system, the value of charge is $1.6 \times {10^{ - 19}}C$ and the distance is in the metres $\left( {1{A^ \circ } = {{10}^{ - 10}}m} \right)$ to a molecule, more the bond angle, lesser is the value of dipole moment.
3. Representation- Direction of the dipole is indicated with the help of an arrow head $\left( { + \to } \right)$ pointing towards the more electronegative element.

Note:
It is clear that presence of polar bonds in a polyatomic molecule does not mean the molecule as a whole has a dipole moment. In the case of molecules such as carbon dioxide and methane, the arrangement of individual bonds in molecules is such that the net dipole moment is zero.
It must be noted that the polarity of an individual bond depends upon the electronegativity difference of the atoms forming the bond but the polarity of a molecule as a whole depends upon its dipole moment.