Based on Table N, which phrase describes the half-lives and the decay modes of uranium-235 and uranium-238?

Regents Chemistry Exam June 2025 Question 28

28 Based on Table N, which phrase describes the half-lives and the decay modes of uranium-235 and uranium-238?

(1) the same half-life but different decay modes (2) the same half-life and the same decay mode (3) different half-lives and different decay modes (4) different half-lives but the same decay mode

Solution:

All we need to do is to find Table N on the Reference Table and find uranium-235 and uranium-238 there. We can then locate their half-lives and decay modes. Uranium-235 has a half life of 7.4*10^8 years and alpha decay mode, while uranium-238 has a half life of 4.47*10^9 years and alpha decay mode. Choice 4 is the correct answer.

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