Question

# The lattice enthalpy and hydration enthalpy of four components are given below:CompoundLattice enthalpy (kJ/mol)Hydration enthalpy (kJ/mol)P+780-920Q+1012-812R+828-878S+632-600The pair of compounds which is soluble in water is:a) P and Qb) Q and Rc) R and Sd) Q and Se) P and R

As we know that, the lattice enthalpy of a crystalline solid is a measure of the energy released when ions are combined to make a compound. It is a measure of the cohesive forces that bind ions. Lattice energy is relevant to many practical properties including solubility, hardness and volatility. The concept of lattice energy was originally developed for rock salt structured and sphalerite structured compounds like $NaCl$ and $ZnS$, where the crystal occupies high symmetry crystal lattice sites.