The half-life of a radioactive substance is 15 hours. If at some instance, the sample has a mass of 512 g, calculate the time it will take 78 of the sample to decay by Sunday | Jan 9 | Physics WAEC | 0 comments A. 15 hours B. 30 hours C. 45 hours D. 60 hours Correct Answer: Option C – 45 hours Users Also Read These:The number of protons in an element increased by one…Two radioactive elements Q and S have half-life…A radioactive substance has a half-life of 20 hours.…A radioactive element has a decay constant of…A radioactive substance has a half-life of 20 hours.…