Explanation:Pyro acids are formed (conceptually if not in practice) by condensing two molecules of the ortho acid with the elimination of a water molecule. Thus pyrophosphoric acid is H4P2O7. (Note that this = 2 H3PO4 - H2O). Pyrosulfuric acid is H2S2O7, which = 2 H2SO4 - H2O.
