For the reaction ${\mathrm{CH}}_3{\mathrm{COOCH}}_3+{\mathrm{H}}_2\mathrm{O}\stackrel{{\mathrm{H}}^{+}}{\to }{\mathrm{CH}}_3\mathrm{COOH}+{\mathrm{CH}}_3\mathrm{OH}$. The progress of the process of reaction is followed by 

Finding the amount of acetic acid formed at different intervals

Finding the amount of methanol formed at different intervals 

Using a voltmeter

Using a polarimeter