Question : If the rate constant for a first order reaction is k , the time (t) required for the completion of 99% of the reaction is given by

(1) t=0.693/k

(2) t=6.909/k

**(3) t=4.606/k**

(4) t= 2.303/k

answer : from all above options the correct answer is “

**(3) t=4.606/k**“solution is given below –

For first order reaction , we have as follows

after the calculation we can say that the correct answer is option (3) that “

**(3) t=4.606/k**“extra details : as know that the first order reactions are those reactions in which reaction rate is linearly dependent on the concentration of only on one reactant and how to solve these types of questions can be seen in the solution given above.