2 answers
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Yes, you are correct. An isotope is considered stable if it meets any of the following criteria:
1. The isotope does not emit a form of radiation (option A).
2. The isotope's half-life is longer than the average human life (option B is incorrect because it refers to human life and not stability).
3. The isotope emits some form of radiation (option C is incorrect because it refers to an unstable isotope).
4. The isotope's half-life is too long to be measured (option D is incorrect because it refers to difficulty in measurement, not stability).