Which of the following order of L.E. is not correct :-

Options

A. `Al_(2)O_(3) lt MgO lt Na_(2) O`
B. `NaF lt MgO lt ScN lt TiC`
C. `KBr lt LiF lt MgO`
D. `LiF gt NaF gt KF`

Explanation

To determine which order of lattice energy (L.E.) is incorrect, we need to analyze the given compounds based on the charges of their ions and their ionic sizes. Lattice energy is influenced by two main factors: the charge of the ions and the distance between them (interionic distance).

### Step-by-Step Solution:

1. **Understanding Lattice Energy**:
- Lattice energy is directly proportional to the charge of the ions and inversely proportional to the distance between them.
- Higher charges lead to higher lattice energy, while larger ionic sizes (greater interionic distance) lead to lower lattice energy.

2. **Analyzing Each Option**:
- **Option D**: Lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF)
- All ions have the same charges (+1 and -1).
- As we move down the group, the size of the cations increases (Li < Na < K), leading to increased interionic distance.
- Therefore, the order of lattice energy should be:
\[ \text{LiF} > \text{NaF} > \text{KF} \]
- This order is correct.

- **Option C**: Potassium bromide (KBr), lithium fluoride (LiF), magnesium oxide (MgO)
- Charges: K (+1), Br (-1); Li (+1), F (-1); Mg (+2), O (-2).
- MgO has the highest charge, thus it should have the highest lattice energy.
- KBr has larger ions compared to LiF, leading to lower lattice energy.
- The expected order should be:
\[ \text{MgO} > \text{LiF} > \text{KBr} \]
- This order is correct.

- **Option B**: Sodium fluoride (NaF), magnesium oxide (MgO), strontium chloride (SrCl2), titanium carbide (TiC)
- Charges: Na (+1), F (-1); Mg (+2), O (-2); Sr (+2), Cl (-1); Ti (+4), C (-4).
- As we move from NaF to TiC, the charges increase, leading to an increase in lattice energy.
- Therefore, the expected order should be:
\[ \text{TiC} > \text{MgO} > \text{SrCl2} > \text{NaF} \]
- This order is correct.

- **Option A**: Aluminum oxide (Al2O3), magnesium oxide (MgO), sodium oxide (Na2O)
- Charges: Al (+3), O (-2); Mg (+2), O (-2); Na (+1), O (-2).
- The charge on Al2O3 is higher than that of MgO and Na2O, leading to higher lattice energy.
- The expected order should be:
\[ \text{Al2O3} > \text{MgO} > \text{Na2O} \]
- This order is correct.

3. **Identifying the Incorrect Order**:
- After analyzing all options, we find that all orders presented are correct based on the principles of lattice energy. However, the question asks for the incorrect order.
- Since all options are correct, we conclude that the question may have been misleading or incorrectly framed.

### Conclusion:
The incorrect order of lattice energy is not explicitly provided in the options, as all analyzed orders are consistent with the principles of lattice energy.