Achemical substance has a decay rate of 6.9% per day. the rate of change of an amount n of the chemical is given by the equation dn/dt = - 0.069 n where t is the number of days since decay began. complete parts a) through c). a) let n_0 represent the amount of the chemical substance at t = 0. find the exponential function that models the situation. n(t) = n_0 b) suppose that 800 g of the chemical substance is present at t = 0. how much will remain after 2 days? after 2 days, g will remain. after 2 days, g will remain. (round to the nearest whole number as needed.) c) after how many days will half of the 800 g of the chemical substance remain? after days, half of the chemical substance will remain. (round to one decimal place as needed.)