NH3 dissolves in water. PH3 does not dissolve in water. Xpln

When ammonia is passed through water : The Ammonia molecule has the capability to form a dative bond due to the lone pair of electrons.There is the formation of a H-bond due to the strong dipole-dipole attraction the ammonia dissolves in water. When phosphine is passed in water('slightly' soluble): the lone pair on phosphorus may be regarded as predominantly formed by the 3s orbital of phosphorus. Therefore,it forms weak hydrogen bonds.Thus, the H-Bond is weak and it is only slightly soluble.Phosphine dissolves more readily in non-polar solvents than in water because of the non-polar P-H bonds but water is polar in nature.