A: Higher the charge density on the central ion, greater will be stability of the complex
R: Hard acid show a greater tendency for forming complexes with hard ligands such as F

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. ) If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To solve the assertion-reason question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step 1: Analyze the Assertion (A)
The assertion states: "Higher the charge density on the central ion, greater will be the stability of the complex."

- **Understanding Charge Density**: Charge density is defined as the amount of charge per unit volume. A higher charge density means that the central ion has a greater charge and a smaller size.
- **Effect on Stability**: When the central ion has a high charge density, it can attract ligands more effectively due to stronger electrostatic forces. The smaller size allows the central ion to approach ligands closely, reducing the distance between them, which increases the attraction according to Coulomb's law (the electrostatic force is inversely proportional to the square of the distance).
- **Conclusion**: Therefore, the assertion is correct: higher charge density leads to greater stability of the complex.

### Step 2: Analyze the Reason (R)
The reason states: "Hard acids show a greater tendency for forming complexes with hard ligands such as F-."

- **Understanding Hard Acids and Bases**: According to Pearson's hard and soft acid-base theory, hard acids (like H+, Li+, Mg2+, etc.) prefer to form complexes with hard bases (like F-, Cl-, OH-, etc.) due to their similar properties (high charge density and low polarizability).
- **Relation to Assertion**: While this statement is true, it does not directly explain the assertion about charge density and complex stability. The assertion focuses on the stability of complexes due to charge density, while the reason discusses the preference of hard acids for hard ligands.

### Step 3: Conclusion
- Both the assertion and the reason are correct statements.
- However, the reason does not serve as a correct explanation for the assertion.

### Final Answer
Based on the analysis, the correct option is:
**Option 2: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.**

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