Question

Which of the following molecules has polar bonds but is a non – polar molecule?
A.\[{H_2}\]
B.\[{H_2}O\]
C.\[N{H_3}\]
D.NaCl
E.\[C{O_2}\]

Answer 1

Hint: A polar bond is a covalent bond between two atoms where the electrons forming the bond are unequally distributed. Due to this the molecule has a slight electrical dipole moment, in which one end is slightly positive whereas the other is slightly negative.

Complete Step-by-Step Answer:
Before we move forward with the solution of the given question, let us first understand some important basic concepts. Covalent bonds are formed between atoms when there is a sharing of valence electrons between the combining atoms. These bonds help to complete the octet state of the combining atoms. Now, when covalent bonds are formed, the electrons that are bonding the two atoms are unequally distributed. This happens due to the difference in electronegative character of the combining atoms. The atom with higher electronegativity would tend to pull the electron cloud towards itself. Such an unequal distribution of the electron cloud results in the formation of a slight dipole moment in the molecule, where one end is slightly more positive while the other is a slightly more negative. Such a bond is known as a polar bond.

Let us discuss the options given to us:
1.\[{H_2}\]: The bonding atoms are the same and hence there is no electronegative difference between them. Hence it is a non -polar molecule
2.\[{H_2}O\]: Oxygen is more electronegative than hydrogen, hence the water molecule is polar in nature.
3.\[N{H_3}\]: Similarly, in ammonia, nitrogen is more electronegative than hydrogen, hence the ammonia molecule is polar in nature.
4.NaCl: NaCl is an ionic compound.
5.\[C{O_2}\]: Carbon dioxide has a linear molecular structure. There is also an electronegativity difference between the carbon and oxygen atoms. Because of this, polar bonds are formed. But since these bonds are placed exactly opposite to each other, the net dipole moment becomes zero.

Hence, Option E is the correct option

Note: If the electrons are shared equally between the combining atoms, then there would be no shift in the electron cloud and hence that compound would be a non – polar molecule.