#12 1 point americium-241 (am-241) is used in residential smoke detectors. particles emitted as am-241 decays cause the air in a smoke alarm to ionize, allowing current to flow between two electrodes. if smoke absorbs the particles, the current changes and sets off the alarm. the half-life of am-241 is 432 years a. write a decay law for the isotope. use c to represent the initial amount of americium-241 a(t) b. use the decay law to answer the question: how long will it take for 25% of the am-241 to decay? . give your answer accurate to the nearest 10 years years