The half-life of a radioactive substance is 10 years. What fraction of the substance remains after 30 years?
Q1. The half-life of a radioactive substance is 10 years. What fraction of the substance remains after 30 years?
Answer: 1/8
Explanation: After 3 half-lives, the fraction remaining is (1/2)^3 = 1/8. Option 'C' is wrong as it's after 1 half-life.