Plutonium-240 decays according to the function \[q(t)=q _{o}e ^{-kt}\] where q represents the quantity remaining after t years and k is the decay constant, 0.00011.. how long will it take 36 grams of plutonium-240 to decay to 12 grams? . a. 18,900 years. b. 1.44 years. c. 9,990 years. d. 2,100 years.