The decomposition of an insecticide follows first order kinetics with a rate
constant of 1.45 yr^-1. A farmer spilled a container of the insecticide on March 1, 2018 causing a drainage pond to have an insecticide concentration of 5.0 x 10^-7 g/mL. What is the concentration of this contaminated pond on March 1, 2019?
There may be a shorter way but here is what I would do.
ln(Co/C) = kt where Co is concn today and C is concn later.
ln(5e-7/C) = 1.45 yr^-1*1 yr
Solve for C in g/mL one year later. Post your work if you get stuck.