Answer
The chemical equation that represents the process of lattice energy for $NaCl$ is $$NaCl (s)\rightarrow Na^+(g)+Cl^-(g)$$
Work Step by Step
Again, by definition, lattice energy is the energy required to completely separate one mole of a solid ionic compound into its gaseous ions.
So the chemical equation that represents the process of lattice energy for $NaCl$ is in fact the chemical equation that represents the separation of solid $NaCl$ compound into 2 gaseous ions $Na^+$ and $Cl^-$.
Therefore, that equation would be $$NaCl (s)\rightarrow Na^+(g)+Cl^-(g)$$
$(s)$ stands for solid and $(g)$ stands for gaseous.
