KEAM 2016 Physics and Chemistry Paper

If hydration energy is greater as compare to lattice energy then the salt is soluble, and if hydration energy is lesser as compared to lattice energy, then salt is insoluble. LiF is almost insoluble due to high lattice energy. Both ions in LiF are very small. In this case, hydration energy. s very less.
In case of Csi both ions are larger in size As a result both the ions in Csl are less hydrated therefore, its hydration energy will decrease Hence, it is insoluble in water