Concept:Lattice energy is directly proportional to the product of ionic charges and inversely proportional to the sizes (radii) of the ions.
Formula:$$ \text{Lattice Energy} \propto \frac{q_1 q_2}{r_1 + r_2} $$
Solution:- All the given options consist of +1 cations and -1 anions, so the charge product is constant.
- We must look at the ionic sizes. The smaller the ions, the closer they pack, resulting in higher lattice energy.
- Among the cations, \( \text{Li}^+ \) has the smallest ionic size compared to \( \text{Na}^+ \) and \( \text{K}^+ \).
- Therefore, \( \text{LiCl} \) possesses the maximum lattice energy due to having the smallest internuclear distance.
Why other options are incorrect:- A, B, C: They contain larger cations (\( \text{Na}^+ \), \( \text{K}^+ \)) or larger anions (\( \text{Br}^- \)), which increases the distance between charges and weakens the lattice energy.
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