Which of the following best describes what occurs during one half-life of a radioactive substance?

• A. All of the substance is converted into a stable isotope.
• B. The substance stops emitting radiation.
• C. The rate of decay doubles.
• D. Half of the original amount of the substance decays.

Answer: (D)

Verified step by step guidance

1. Understand the concept of a half-life: it is the time required for half of the radioactive nuclei in a sample to decay.
2. Recognize that during one half-life, exactly half of the original amount of the radioactive substance transforms into its decay products, not necessarily a stable isotope immediately.
3. Note that the substance continues to emit radiation during and after the half-life because some radioactive nuclei remain undecayed.
4. Understand that the rate of decay does not double; instead, it decreases over time as fewer radioactive nuclei remain.
5. Conclude that the best description of what occurs during one half-life is that half of the original amount of the substance decays.