A factory buys 100 kg of radioactive chemical witha half life of 5 years which decays to a stable compound. How much of the chemical will still be radioactive in 10 years time?
Correct answer: B. 25 kg
- A. None
- B. 25 kg
- C. 75 kg
- D. 50 kg
Explanation
The concept of half-life is crucial in understanding how radioactive substances decay over time. The half-life is the time required for half of the radioactive nuclei in a sample to decay. In this question, the half-life is given as 5 years. Therefore, in 10 years, which is two half-lives, the sample will go through two stages of halving:1. After the first 5 years, 50 kg of the original 100 kg remains radioactive.2. After the next 5 years (totaling 10 years), half of the remaining 50 kg will decay, leaving 25 kg of radioactive material.Therefore, the correct answer is 25 kg. Options 'None' and '75 kg' misunderstand the concept of decay, while '50 kg' only accounts for one half-life instead of two.
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