The polaarsation power is maximum of which of the following ion

Options

A. `Mg^(+2)`
B. `K^(+)`
C. `Cs^(+)`
D. `Al^(3+)`

Answer

To determine which ion has the maximum polarization power, we can follow these steps:

### Step 1: Understand Polarization Power
Polarization power is the ability of a cation to distort the electron cloud of an anion. The factors that influence polarization power include the size of the cation and its charge. Smaller cations with higher positive charges have greater polarization power.

### Step 2: Apply Fajans' Rule
Fajans' Rule states that:
- A small-sized cation with a high positive charge will have a greater ability to polarize a large-sized anion.
- The charge density (charge/size) is crucial; higher charge density leads to stronger polarization.

### Step 3: Analyze the Given Ions
Let's consider the ions provided in the options:
1. Mg²⁺
2. K⁺
3. Cs⁺
4. Al³⁺

### Step 4: Compare Size and Charge
- **Mg²⁺**: Small size, +2 charge
- **K⁺**: Larger size, +1 charge
- **Cs⁺**: Largest size, +1 charge
- **Al³⁺**: Small size, +3 charge

### Step 5: Determine Charge Density
- **Mg²⁺**: Charge density = 2/size (small)
- **K⁺**: Charge density = 1/size (larger)
- **Cs⁺**: Charge density = 1/size (largest)
- **Al³⁺**: Charge density = 3/size (small)

### Step 6: Identify the Ion with Maximum Polarization Power
From the analysis:
- **Al³⁺** has the smallest size and the highest positive charge (+3). Therefore, it has the highest charge density and thus the maximum polarization power.

### Conclusion
The ion with the maximum polarization power is **Al³⁺**.

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