Statement I : Ammonia is highly soluble in water, solubility of other hydrides of 15th group is very lessStatement II : Ammonia can form H-bonds with water ,  other hydrides of 15th group cannot involve in H-bonding

Covalent compounds like NH3, HF, lower alcohols , lower carboxylic acids, H2O2 are capable of forming intermolecular H-bonding with water.Thus they all are soluble in water.PH3,AsH3,SbH3 and BiH3 cannot form H-bonds with water becauseX-H bond in them is less polar due to large size and lesser electronegativity of the central atom;