Question

Identify the non-polar molecule in the set of compounds given:
(A) ${{H}_{2}}$
(B) $HCl$
(C) $HF$
(D) $HBr$

Answer 1

Hint: A molecule can be polar or nonpolar depending upon the electronegativity difference between the two atoms of a bond. A bond is said to be polar if the two atoms of the bond have an electronegativity difference; that is, one of the atoms of the bond attracts the shared pair of electrons more strongly towards itself than the other. whereas it is said to be non-polar, if there is no or little electronegativity difference between the two atoms. This means both the atoms have an equal tendency to attract the shared pair of electrons.

Complete Step by Step Answer:
(A) ${{H}_{2}}$ - In this molecule, similar atoms are attached to a bond. That is, both the atoms have the same tendency to attract the shared pair of electrons. Neither of the atoms will get any charge. Hence, ${{H}_{2}}$ is non-polar.

(B) $HCl$ - In this molecule, two atoms attached to the bond have an electronegativity difference. $Cl$ is a more electronegative element than $H$. So, $Cl$will attract the shared pair of electrons more strongly towards itself. Hence, it is a polar molecule.

(C) $HF$ - $F$ is a more electronegative element than $H$. So, $F$will get a negative charge and $H$ will get a positive charge. Hence, it is a polar molecule.

(D) $HBr$ - Here, $Br$ is a more electronegative element than$H$. So, it is a polar molecule.
Correct Option: (A) ${{H}_{2}}$.

Note: The dipole moment is a vector quantity that has both magnitude and direction. The direction of a dipole moment in a polar molecule is from a more electronegative element to a less electronegative element.