Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R Assertion A : Zero orbital overlap is an out of phase overlap. Reason R : It results due to different orientation / direction of approach of orbitals. In the light of the above statements, choose the correct answer from the options given below

Both A and R are true and R is the correct explanation of A

Both A and R are true but R is NOT the correct explanation of A

Structure of Atom PYQ — JEE Main 2022 · 28 Jul · Shift 2 · Q1 with Solution

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Correct answer: A

Understand the assertion

Assertion $A$ : "Zero orbital overlap is an out of phase overlap."

In orbital overlap, there are two important possibilities:
- In-phase overlap $\rightarrow$ constructive overlap, electron density increases between nuclei.
- Out-of-phase overlap $\rightarrow$ destructive interaction, leading to cancellation.
When the overlapping parts of orbitals have opposite phases/signs, the net overlap integral can become zero due to cancellation. This is often referred to as zero overlap or non-bonding overlap in this context. Hence, the assertion is taken as true.
Understand the reason

Reason $R$ : "It results due to different orientation / direction of approach of orbitals."

Zero overlap commonly arises when orbitals approach in such a way that their symmetry/orientation does not permit effective overlap. For example, because of the relative orientation of orbitals, positive and negative lobes may cancel each other, giving net overlap zero.

Therefore, the reason is also true.
Check whether the reason explains the assertion

The assertion says zero overlap corresponds to out-of-phase overlap.

The reason explains that this happens because of the orientation / direction of approach of orbitals, which causes cancellation of overlap.

So, $R$ correctly explains $A$ .
Conclusion
- Assertion $A$ is true.
- Reason $R$ is true.
- Reason $R$ is the correct explanation of Assertion $A$ .

Thus, the correct option is:

$\boxed{A}$

View written solutionFree

Correct answer: A

Understand the assertion

Assertion $A$ : "Zero orbital overlap is an out of phase overlap."

In orbital overlap, there are two important possibilities:
- In-phase overlap $\rightarrow$ constructive overlap, electron density increases between nuclei.
- Out-of-phase overlap $\rightarrow$ destructive interaction, leading to cancellation.
When the overlapping parts of orbitals have opposite phases/signs, the net overlap integral can become zero due to cancellation. This is often referred to as zero overlap or non-bonding overlap in this context. Hence, the assertion is taken as true.
Understand the reason

Reason $R$ : "It results due to different orientation / direction of approach of orbitals."

Zero overlap commonly arises when orbitals approach in such a way that their symmetry/orientation does not permit effective overlap. For example, because of the relative orientation of orbitals, positive and negative lobes may cancel each other, giving net overlap zero.

Therefore, the reason is also true.
Check whether the reason explains the assertion

The assertion says zero overlap corresponds to out-of-phase overlap.

The reason explains that this happens because of the orientation / direction of approach of orbitals, which causes cancellation of overlap.

So, $R$ correctly explains $A$ .
Conclusion
- Assertion $A$ is true.
- Reason $R$ is true.
- Reason $R$ is the correct explanation of Assertion $A$ .

Thus, the correct option is:

$\boxed{A}$