Assertion: Transitio metals show variable valence.
Reason : Due to a large energy difference bteween the `ns^(2)` and `(n - 1)d` electrons.

Options

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

Explanation

To solve the problem, we need to analyze the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that "Transition metals show variable valence." This is true because transition metals can lose different numbers of electrons from their d and s orbitals, leading to various oxidation states.

### Step 2: Understand the Reason
The reason given is "Due to a large energy difference between the ns² and (n-1)d electrons." This statement is incorrect. In transition metals, the energy difference between the ns and (n-1)d orbitals is actually small. This small energy gap allows for the easy removal of electrons from both the s and d orbitals, contributing to the variable valency.

### Step 3: Conclusion
Since the assertion is true and the reason is false, we conclude that the correct relationship is that the assertion is true, but the reason is not valid.

### Final Answer
The assertion is true, and the reason is false. Therefore, the correct answer is option C.

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