In the following question, Assertion (A) is given followed by a statement of Reason (R). Choose the correct answer. Assertion (A): π(2px),π(2py),π*(2px),π*(2py) molecular orbitals have one nodal plane each. Reason (R) : All the molecular orbitals formed by the sideways overlapping have one nodal plane.
To answer this question, let's first analyze the Assertion (A) and the Reason (R) separately and then relate them. Analysis of Assertion (A): The assertion states that the molecular orbitals π(2px),π(2py),π*(2px),π*(2py) all have one nodal plane each. The molecular orbitals formed by the combination of p atomic orbitals in a sideways manner are indeed termed as π and π* orbitals. Specifically, π orbitals are bonding molecular orbitals with no nodal planes through the bonding region, whereas π* orbitals are antibonding molecular orbitals with one nodal plane through the bonding region. Thus, π orbitals should ideally have no nodal planes through the bonding region, and π* orbitals should have one. Therefore, the assertion that all the mentioned orbitals, including the π orbitals, have one nodal plane each is incorrect. Analysis of Reason (R): The reason given states that all molecular orbitals formed by the sideways overlapping have one nodal plane. This is a generalized statement that is not fully accurate. The π molecular orbitals, formed by sideways overlap of unhybridized p orbitals, typically have no nodal planes through the bonding region (areas between the nuclei involved in bonding), whereas π* orbitals, which are antibonding, do have such a nodal plane. Thus, the reason is overly generalized and misleading. Conclusion: Given the incorrect statement in both the assertion and the reason, and the incorrect association between them, the correct option is: Option B: Both assertion and reason are false.