An unknown mixture contains one or two of the following : CaCO3 , BaCl2 , AgNO3 , Na2SO4 , ZnSO4 and NaOH . The mixture is completely soluble in water and solution gives pink colour with phenolphthalein. When dilute hydrochloric acid is gradually added to the solution, a precipitate is formed which dissolves with further addition of the acid.
The aqueous solution of mixture gives white precipitate with dil. HCl which dissolves in excess of dil. HCl . It confirms:
a. BaCl2+NaOH
b. Na2SO4+NaOH
c. ZnSO4+NaOH
d. AgNO3+NaOH