Which of the following reactions occurs at measurable rate ?

1)H++OH-→H2O; This is an instantaneous reaction.2)AgNO3+ NaCl → AgCl↓ + NaNO3;This is an instantaneous reaction.4) 2H2+O2→absence of catalyst2H2O This is a very slow reaction.In the first two cases (option 1 & 2) before measuring the rate, reaction gets completed.In the third case (option 4) no reaction occurs even after considerable timeThus option to (3), Hydrolysis of methylacetate occurs with measurable rate.