What is the value of the rate constant of a first-order process that has a half-life of 225 s?

The value of rate constant of first order process that has half life of 225s is calculated as follows

t (1/2) = 0.693/k where k is gas constant

225 s = 0.693/k multiply both side by k

225 k = 0693 divide by 225

k = 3.08 x10^-3