Question

Superman is in some ways a living solar battery; his cells absorb electromagnetic radiation from stars (like Earth's sun). The radioactivity of kryptonite possibly interferes with this process, driving the energy out of his cells in a painful fashion. Long term and high-level exposure to green kryptonite can be fatal to Superman. For this reason, Superman spends a significant amount of time studying kryptonite. He performs an experiment to determine its half-life. He begins with 1.5 mols of kryptonite atoms (9.03E23 atoms). After 15 years, he returns and finds that 5.85E23 kryptonite atoms still remain. What is the half-life of kryptonite? 24 years 242 years 9.7 years 220 years 267 years

Answer 1

Use the given number of atoms and time to find the required decay constant and use that to find the half life as shown below

N = No erat s No = initial no atoms of 5.85 x 1023 = (9.03X1023) e -2(154) 2 - 0.028941 y ? en 2 en2 2 = 0.028941412 il 24) years