Given below are two statements, one is labelled as assertion (A) and other is labeled as reason (R).

(A) : Water is a good solvent for ionic compounds but poor one for covalent compounds 
(R) : Hydration energy of ions releases sufficient energy to overcome lattice energy and break hydrogen bonds in water, while covalent bonded compounds interact so weakly that even vander waal’s forces between molecules of covalent compounds cannot be broken

Water is a good solvent for ionic compounds because both are polar, where as covalent compounds are nonpolar.

The hydration energy release from the solvation of ionic compounds is high enough to overcome the Lattice energy as well as the H-bonding between H₂O molecule so that it can soluble. While Covalent bonded compounds interact so weakly(due to its less polarity) that even vander waals forces between molecules of covalent compounds can not be broken. 

Hence, Both (A) and (R) are true and (R) is the correct explanation of (A)