Afirst-order reaction has a rate constant of 0.33 min-1. it takes min for the reactant concentration to decrease from 0.13 m to 0.088 m

The first order reaction is when the rate of the reaction is directly proportional to the concentrations of one of the reactants.
if the reactant whose concentration determines the rate - N
rate equation is 
rate = k [N]¹
where k - rate constant 
the differential equation is as follows;
[N] = [N₀] e^ (-kt)
where N - concentration after t minutes
N₀ - concentration when t = 0 minutes 
k -rate constant 
t - time taken in minutes 
substituting the values given following equation is obtained 
0.088 m = 0.13 e^ (-0.33 *t)
e^ (-0.33 *t) = 0.088/ 0.13
       -0.33t      = ln 0.676
       - 0.33t     = -0.39
                t = 1.18 minutes
it takes 1.18 minutes for reactant concentration to decrease from 0.13 m to 0.088 m

The answer is a) carbon-12