Question

Given below are two statements:
Statement (I): A $\pi$ bonding MO has lower electron density above and below the inter-nuclear axis.
Statement (II): The $\pi^*$ antibonding MO has a node between the nuclei.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are false
• B. Both Statement I and Statement II are true
• C. Statement I is false but Statement II is true
• D. Statement I is true but Statement II is false

Answer 1

Answer: (C)

Statement I is false but Statement II is true

Answer 2

Statement (I) Analysis:
A $\pi$ bonding molecular orbital (MO) is formed by the sideways overlap of $p$-orbitals.
This type of bonding MO has higher electron density above and below the internuclear axis, leading to a bonding interaction between atoms.
Therefore, Statement (I) is false.
Statement (II) Analysis:
The $\pi^*$ antibonding molecular orbital is formed when $p$-orbitals combine in such a way that destructive interference occurs between the wave functions of the atomic orbitals.
This creates a node (a region of zero electron density) between the nuclei.
Therefore, Statement (II) is true.