Incorrect statement is

Options

A. `MgO gt AlF_(3) gt MgF_(2):" Lattice energy"`
B. `Ni gt Na gt Mg:"Electron affinity"`
C. `SF_(6)gt PF_(5) gt SiF_(4):" Lewis acidic character"`
D. `SiCl_(4) gt SiBr_(4) gt SiI_(4):"Decreasing order of electronegativity of Si"`

Answer

To solve the question of identifying the incorrect statement among the given options, we will analyze each statement step-by-step.

### Step 1: Analyze the first statement regarding lattice energy
- **Lattice Energy Concept**: Lattice energy is the energy released when ions in the gaseous state form an ionic solid. It is directly proportional to the charges of the ions and inversely proportional to the distance between them.
- **Compounds Given**: MgO, AlF3, MgF2
- **Charges**:
- MgO: Mg²⁺ and O²⁻ (charges = 2 and 2)
- AlF3: Al³⁺ and F⁻ (charges = 3 and 1)
- MgF2: Mg²⁺ and F⁻ (charges = 2 and 1)
- **Lattice Energy Order**:
- AlF3 has the highest lattice energy due to the +3 charge on Al.
- MgO comes next due to the +2 charge on Mg and -2 charge on O.
- MgF2 has the lowest lattice energy due to the +2 charge on Mg and -1 charge on F.
- **Correct Order**: AlF3 > MgO > MgF2
- **Conclusion**: If the first statement claims MgO has the highest lattice energy, it is incorrect.

### Step 2: Analyze the second statement regarding electron affinity
- **Electron Affinity Concept**: Electron affinity is the energy change when an electron is added to a neutral atom.
- **Elements Given**: Nickel (Ni), Sodium (Na), Magnesium (Mg)
- **Trends**:
- Electron affinity generally increases across a period and decreases down a group.
- Sodium (Na) has a lower electron affinity than Magnesium (Mg) due to its single valence electron.
- Nickel (Ni) being a transition metal has a higher electron affinity than both Na and Mg.
- **Correct Order**: Ni > Na > Mg
- **Conclusion**: If the statement claims otherwise, it is incorrect.

### Step 3: Analyze the third statement regarding Lewis acidity
- **Lewis Acid Concept**: A Lewis acid is a substance that can accept an electron pair.
- **Compounds Given**: SF6, PFI, SiF4
- **Acidity Order**:
- SF6 is highly crowded and does not accept electron pairs, making it a weak Lewis acid.
- PFI and SiF4 can accept electron pairs more readily than SF6.
- **Conclusion**: If the statement claims SF6 has the highest Lewis acidity, it is incorrect.

### Step 4: Analyze the fourth statement regarding electronegativity
- **Electronegativity Concept**: Electronegativity is the tendency of an atom to attract electrons in a bond.
- **Compounds Given**: SiCl4, SiBr4, SiI4
- **Trend**: Electronegativity decreases down the group in the periodic table.
- **Correct Order**: SiCl4 > SiBr4 > SiI4
- **Conclusion**: If the statement claims this order, it is correct.

### Final Conclusion
- The incorrect statements identified are from the first, second, and third analyses. The correct answer is the statement that claims MgO has the highest lattice energy, the incorrect order of electron affinity, and the incorrect order of Lewis acidity.