Question

Which of the following has $p\pi - d\pi$ bonding?
A.$NO_3^ -$
B.$CO_3^{ - 2}$
C.$BO_3^{ - 3}$
D.$SO_3^{ - 2}$

Answer 1

Here in the question we need to find the existence of $p\pi - d\pi$ bonding in any one of the given mentions. Now firstly we get that it is a kind of bonding where the p and d orbitals form a $\pi$ bond between the two atoms by sharing electrons between them. Now among the options only Sulphur has the d subshell in the ground state so only $SO_3^{ - 2}$ have tendencies to make that kind of bond.

Complete step by step solution:
In the given question we have to find out the option among the given which have the intermolecular bonding of the $p\pi - d\pi$ kind between the atoms in a particular molecule. This needs to be the indulgence of a covalent bond between the given set of atoms.
Now first we should be aware of the $p\pi - d\pi$ bonding. The $p\pi - d\pi$ bonding denotes a type of covalent bond that is formed by a mutual and conclusive sharing of the electrons of $p\pi$ orbital of one atom to the $d\pi$ orbital of the another element in the same molecule.
This nomenclature denotes the formation of a $\pi$ bond between the two atoms and the lobes they subsequently form.
Now, here we can clearly say that $p\pi - d\pi$ bonding includes d-orbitals, and if we closely observe the mentioned options then we will notice that, $S$ is the only element with the existence of $d$ subshell in the ground state. Although they are unoccupied but can be accessed by the help of excitation.
So we can clearly say that option $SO_3^{ - 2}$ is the right option.

Hence, the correct answer is option D.

Note: A covalent bond, also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.