A radioactive nucleus has a half-life of 3 years. After 9 years, what fraction of the original sample remains?

Study for the High School Physics Test. Study with quizzes, flashcards, and multiple choice questions, each question comes with hints and explanations. Prepare effectively for your exam!

Multiple Choice

A radioactive nucleus has a half-life of 3 years. After 9 years, what fraction of the original sample remains?

Half-life behavior means the amount remaining is halved every half-life. With a 3-year half-life, after 9 years three half-lives have passed (9 ÷ 3 = 3). After each half-life, the fraction left is multiplied by 1/2: 1/2 after the first, 1/4 after the second, and 1/8 after the third. So the original sample remaining is 1/8.

Half-life behavior means the amount remaining is halved every half-life. With a 3-year half-life, after 9 years three half-lives have passed (9 ÷ 3 = 3). After each half-life, the fraction left is multiplied by 1/2: 1/2 after the first, 1/4 after the second, and 1/8 after the third. So the original sample remaining is 1/8.

More practice questions