The time for half life of a first order reaction is 1 hr. what is the time taken for 87.5% completion of the reaction?

The half life period of a first order reaction is 10 minutes. Then its rate constant is

Show that for a first order reaction the time required for 99.9% completion is about 10 times its half life period.

For a first order reaction, the rate constant is 6.909 "min"^(-1) , the time taken for 75% conversion in minutes is

The half life period of a first order reactions is 10 mins. What percentage of the reactant will remain after one hour ?