In a first order reaction, the reactant concentration decreases from 0.8 M to 0.4 M in 15 min. What is the time taken for the concentration to change from 0.1 M to 0.025 M?

In a first order reaction, the concentration of the reactant is decreased from 1.0 M to 0.25 M in 20 minute. The rate constant of the reaction would be

For a given reaction .of first order, it takes 20 minute for the concentration to drop from 1.0 M litre^-1 to 0.6 M litre^-1 time required for the concentration to drop from 0.6 M litre^-1 to 0.36 M litre^-1 will be:

In the first order reaction , the concentration of reactant decrease from 800 mol//dm^3 to 50 mol//dm^3 in 2 xx 10^4 sec . The rate constant for the reaction is

For the reaction, R to P , the concentration of a reactant changes from 0.03 M to 0.02 M in 25 min. calculate the average rate of reaction using units of time both in minutes and seconds.