A first order reaction is 50 % completed in 16 minute. Find the percentage of reactant reacting in 32 minute.

Step-by-step solution

The half-life t_ 1/2 of a first-order reaction is constant and equal to the time required for the reaction to reach 50% completion. Given that this occurs in 16 minutes, we have t_ 1/2 = 16 minutes. A time period of 32 minutes corresponds to 32 16 = 2 half-lives. The fraction of reactant remaining after n half-lives is ( 1 2 )^n , yielding ( 1 2 )^2 = 1 4 remaining. The percentage of reactant reacted is therefore 100 % - 25 % = 75 % . Final answer: D