Question detail

If a radioactive sample has a half-life of 5 years and its initial activity is 1600 Bq, what will be its activity after 15 years?

Try the question, check the answer, then read the explanation to understand the curriculum point.

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At a glance

MCQ

Type

practice

Style

Topic

Atoms and nuclear radiation

Question

A. 200 Bq
B. 400 Bq
C. 800 Bq
D. 1000 Bq

Answer

200 Bq

Explanation

200 Bq is correct because the worked solution uses remaining = initial / 2^n and substitutes the values from the question. This keeps activity, count rate, atomic number, mass number and neutron count distinct for Atomic structure.

Common mistake

Misunderstanding Half-Life Calculations

Students often confuse the concept of half-life with the total decay time, leading to incorrect calculations of remaining count rate or activity.

To accurately calculate the remaining count rate after a number of half-lives, remember that each half-life reduces the count rate by half. Use the formula: remaining count rate = initial count rate × (0.5)^n, where n is the number of half-lives.

Related flashcards

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A radioactive substance has an initial count rate of 800 counts per minute. After 3 half-lives, what will be the remaining count rate? Use the half life sample context to keep Half-lives and the random nature of radioactive decay distinct from nearby atomic and nuclear radiation ideas.