Assertion : In tetrahedral complexes low spin configuration are rarely observed .
Reason : `Delta_(t) = ((4)/(9)) Delta_(0)`

Options

A. If both Assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. if both assertion and reason are false

Explanation

To solve the question regarding the assertion and reason related to tetrahedral complexes, we will analyze both statements step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "In tetrahedral complexes, low spin configurations are rarely observed."
- Tetrahedral complexes are typically formed by transition metals with a coordination number of 4, leading to sp³ hybridization.

2. **Hybridization in Tetrahedral Complexes**:
- In tetrahedral complexes, the hybridization is sp³, meaning that the orbitals involved are one s orbital and three p orbitals.
- Importantly, the 3d orbitals are not utilized in the hybridization process for tetrahedral complexes.

3. **Spin States**:
- Low spin configurations occur when there is a strong field ligand that causes a significant splitting of the d-orbitals, allowing electrons to pair up in the lower energy orbitals before occupying higher energy orbitals.
- In tetrahedral complexes, the splitting of d-orbitals is relatively small compared to octahedral complexes, leading to a preference for high spin configurations.

4. **Reasoning Behind the Assertion**:
- The reason provided states that "Δt = (4/9) Δ0".
- Here, Δt represents the splitting energy in tetrahedral complexes, while Δ0 represents the splitting energy in octahedral complexes.
- Since Δt is less than Δ0, the energy difference is not sufficient to favor low spin configurations, which require a larger splitting energy to promote electron pairing.

5. **Conclusion**:
- Both the assertion and the reason are true. However, the reason does not directly explain why low spin configurations are rarely observed in tetrahedral complexes. Instead, it provides a factual basis for the energy splitting involved.
- Therefore, the correct conclusion is that both statements are true, but the reason does not adequately support the assertion.

### Final Answer:
Both the assertion and the reason are true, but the reason does not explain the assertion.