Which of the following best describes the definition of half-life?

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

Answer: (B)

Verified step by step guidance

1. Understand that half-life is a concept related to radioactive decay, which describes how unstable atoms lose particles over time.
2. Recognize that half-life specifically refers to the time it takes for half of the atoms in a given radioactive sample to undergo decay, not the time for a single atom or the entire sample to decay.
3. Note that the half-life is a statistical measure, meaning it applies to a large number of atoms rather than individual atoms.
4. Eliminate incorrect options: it is not the time for one alpha particle emission, nor the time for all atoms to decay, nor the time for the sample to increase in mass.
5. Conclude that the best description of half-life is: 'The time required for half of the atoms in a radioactive sample to decay.'