Question
Strontium-90 is a radioactive form of the element strontium that undergoes radioactive decay. The graph shows the decay of strontium-90 over time. How long will it take until only 25 percent of the strontium-90 remains? 56 years 28 years 112 years
Answer
4.3
(275 Votes)
Vaughn
Elite · Tutor for 8 years
Answer
#ExplanationThe decay of a radioactive substance like Strontium-90 is a first-order process, which means it follows an exponential decay pattern. The time it takes for half of the substance to decay is called the half-life. The half-life of Strontium-90 is 28 years.To find out how long it will take until only 25 percent of the Strontium-90 remains, we need to understand that 25 percent remaining means 75 percent has decayed. This is equivalent to the substance undergoing two half-lives. After one half-life (28 years), 50 percent of the substance would remain. After another half-life (another 28 years), half of the remaining 50 percent would decay, leaving 25 percent of the original substance.#AnswerTherefore, it will take 2 * 28 = 56 years for only 25 percent of the Strontium-90 to remain. The correct answer is "56 years".