when ditule solution of 20 valume hydrogen peroxide solution was heated the total valume of axygen collected was 120cm in just 15mins .what was the rate of formationof axygen ean of the reaction is very essential.
The average rate was 120cm^3/15min= ...
Now it is most likely the rate was not constant, but an exponential function (max at beginning, min at end). I am not certain of your needs on this.