What is the half-life of an isotope that decays to 12.5% of its original activity in 19.8 hours?

i'm pretty sure it is letter c.) car

hurricanes form when warm, moist air from the ocean surface quickly rises into the atmosphere and forms storm clouds and rain. when the clouds are formed, heat is released which warms the cool air in the upper regions of the atmosphere so that the cycle can continue. which two phases of the water cycle are repeated in this process?

the maximum mass of nh3 is nh3 in grams