Question

Which formula represents a polar molecule?
(1) H2 (3) CO2
(2) H2O (4) CCl4

Answer 1

molecules are said to be polar when there is a net dipole moment. 3D structures of molecules play an important role in this effect. Symmetrical molecules cancel out net dipile to 0.

H2, CO2 and CCl4 are all symmetrical, thus are non-polar.

H2O is structurally bent. It is polar.

Answer 2

$\boxed{\left( 2 \right){\text{ }}{{\text{H}}_2}{\text{O}}}$ represents a polar molecule.

Further Explanation:

The chemical bond is the attraction between atoms, molecules or ions that is responsible for the formation of chemical compounds. It is formed either due to electrostatic forces or by the sharing of electrons.

An ionic bond is formed by the interaction of a metal with a non-metal. Metals are electropositive in nature so they have the tendency to lose electrons whereas non-metals tend to gain electrons due to their high electronegativity. Metal atoms form cations by loss of electrons and non-metals become anions with the gain of electrons.

A covalent bond is a bond formed by the mutual sharing of electrons between the bonded atoms. It is also known as a molecular bond. Such bonds usually exist between two or more non-metals.

Electronegativity difference and symmetry determine the bond polarity in any molecule. Electrons are attracted towards more electronegative atom, thereby developing negative charge on itself and leaving the less electronegative atom with positive charge. If a molecule is symmetrical in nature, it will be non-polar, even there is electronegativity difference between the bonded atoms.

(1) ${{\text{H}}_{\text{2}}}$  

This is formed by the combination of two H atoms so there is no electronegativity difference between the bonded atoms and therefore this molecule is non-polar in nature (For structure, refer to the attached image).

(2) ${{\text{H}}_{\text{2}}}{\text{O}}$  

This is formed by the combination of two H atoms and one O atom. Electronegativity difference exists in this molecule and also it is not symmetrical in nature (For structure, refer to the attached image). Therefore   ${{\text{H}}_{\text{2}}}{\text{O}}$ is a polar molecule.

(3) ${\text{C}}{{\text{O}}_{\text{2}}}$  

This molecule is symmetrical in nature so dipole moment gets cancelled out and therefore ${\text{C}}{{\text{O}}_{\text{2}}}$ is non-polar in nature (For structure, refer to the attached image).

(4) ${\text{CC}}{{\text{l}}_{\text{4}}}$  

This molecule is symmetrical in nature so dipole moment gets cancelled out and therefore ${\text{CC}}{{\text{l}}_{\text{4}}}$ is non-polar in nature (For structure, refer to the attached image).

Learn more:

1. Identification of ionic bonding: https://brainly.com/question/1603987
2. Which is a covalent compound? https://brainly.com/question/2083444

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Ionic and covalent compounds

Keywords: polar, non-polar, CCl4, CO2, H2, H2O, symmetrical, dipole moment, chemical bond, ionic bond, covalent bond.