NH4)2SO4: this is a strong electrolyte, and soluble in water
Ti3(PO4)2 : releases 3 ions and 2 anions in water, it is in- soluble , therefore a weak eletrolyte .
NiCO3 :This is not soluble in water , therefore it is a non- electrolyte
So, NICO3 and Ti3(PO4)2 will form nonelectrolyte solutions when added to deionized water