Which reactants form the salt CaSO4(s) in a neutralization reaction?
(1) H2S(g) and Ca(ClO4)2(s)
(2) H2SO3(aq) and Ca(NO3)2(aq)
(3) H2SO4(aq) and Ca(OH)2(aq)
(4) SO2(g) and CaO(s)
The answer is (3) H2SO4(aq) and Ca(OH)2(aq). The neutralization reaction will not change the valence of elements. For (4), SO2 reacts with CaO is called synthesis reaction.
