In the following questions, a statement of assertion (A) is followed by a statement of reason (R )
A : Lattice energy of CaO is higher than LiCl.
R : Lattice energy of ionic compound is directly prportional to the product of charges of ion.

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 question regarding the assertion and reason statements about lattice energy, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Lattice Energy**:
- Lattice energy (U) is the energy released when gaseous ions combine to form an ionic solid. It can be calculated using the formula:
\[ U = -\frac{k \cdot q_1 \cdot q_2}{r_0} \]
- Here, \(q_1\) and \(q_2\) are the charges of the ions, \(r_0\) is the distance between the ions, and \(k\) is a proportionality constant.

2. **Analyzing the Assertion (A)**:
- The assertion states that the lattice energy of CaO is higher than that of LiCl.
- To verify this, we need to calculate the product of the charges of the ions in both compounds.

3. **Calculating Lattice Energy for CaO**:
- For CaO, the ions are \(Ca^{2+}\) and \(O^{2-}\).
- The charges are \(+2\) and \(-2\), respectively.
- The product of the charges is:
\[ q_1 \cdot q_2 = 2 \cdot (-2) = -4 \quad \text{(considering magnitude, we take 4)} \]

4. **Calculating Lattice Energy for LiCl**:
- For LiCl, the ions are \(Li^{+}\) and \(Cl^{-}\).
- The charges are \(+1\) and \(-1\), respectively.
- The product of the charges is:
\[ q_1 \cdot q_2 = 1 \cdot (-1) = -1 \quad \text{(considering magnitude, we take 1)} \]

5. **Comparing Lattice Energies**:
- Since the product of the charges for CaO (4) is greater than that for LiCl (1), we can conclude that:
\[ U_{CaO} > U_{LiCl} \]
- Thus, the assertion (A) is correct.

6. **Analyzing the Reason (R)**:
- The reason states that lattice energy is directly proportional to the product of the charges of the ions.
- From our calculations, we see that higher charge products lead to higher lattice energies, confirming that the reason is also correct.

7. **Conclusion**:
- Both the assertion (A) and the reason (R) are correct, and the reason correctly explains the assertion.

### Final Answer:
Both the assertion and reason are true, and the reason correctly explains the assertion.