Multiple choice Which of the following is NOT correctly matched? Caro's acid: H2S2O5 Marshall's acid: H2S2O8 Oil of vitriol: H2SO4 Pyrosulphuric acid: H2S2O7 Dithionic acid: H2S2O3 Reveal answer Fill a bubble to check yourself E Correct answer Explanation Dithionic acid: H2S2O6 Sulphurous acid: H2S2O3