New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    The half-life of a radioactive substance is 5 hours. How

    much of the substance remains after 15 hours?       
    A 1/2 Correct Answer Incorrect Answer
    B 1/3 Correct Answer Incorrect Answer
    C 1/4 Correct Answer Incorrect Answer
    D 1/8 Correct Answer Incorrect Answer

    Solution

    Each half-life reduces the substance to half. In 15 hours, there are three half-lives (15 ÷ 5). So the remaining amount is: (1/2)³ = 1/8 Hence, 1/8 of the substance remains after 15 hours.

    Practice Next

    Relevant for Exams: