what is poly basic acid molecules?
Acids that contain more than one acidic (ionizable) hydrogen (proton) are called polyprotic or polybasic acids. The dissociation of polyprotic acids occurs in a stepwise fashion, one proton lost at a time.
E.g., H2SO4 is a dibasic acid while H3PO4 is a tribasic acid having two and three ionizable protons respectively.