Which of the following best describes the term 'half-life' in the context of radioactive decay?

• A. The time it takes for all atoms in a radioactive sample to decay.
• B. The time required for a radioactive sample to double in mass.
• C. The time it takes for a radioactive atom to emit one alpha particle.
• D. The time required for half of the atoms in a radioactive sample to decay.

Answer: (D)

Verified step by step guidance

1. Understand that 'half-life' is a term used in radioactive decay to describe the time it takes for a certain fraction of a radioactive sample to decay.
2. Recall that radioactive decay is a random process where unstable nuclei lose energy by emitting radiation, and the number of undecayed atoms decreases over time.
3. Recognize that the half-life specifically refers to the time required for half of the original radioactive atoms in a sample to decay, not all atoms or any other fraction.
4. Note that this means after one half-life, 50% of the original radioactive atoms remain undecayed, after two half-lives 25% remain, and so on, following an exponential decay pattern.
5. Therefore, the best description of half-life is: 'The time required for half of the atoms in a radioactive sample to decay.'