Which of the following is emitted in a process of natural radioactivity?

Analyze the question: It asks which radiations come from natural radioactivity, the spontaneous disintegration of unstable nuclei.

Concept: An unstable nucleus emits three types of radiation:

• Alpha (α) particles: helium nuclei (₂⁴He)
• Beta (β) particles: fast electrons from the nucleus
• Gamma (γ) rays: high-energy electromagnetic waves from the nucleus

X-rays are not emitted by the nucleus in natural radioactivity. They are produced when fast electrons hit a metal target, or when electrons move between inner atomic energy levels, as in an X-ray tube.

Solution:

• A. α and β particles: both are genuine natural radioactive emissions. ✔
• B. α and X-rays: X-rays are not nuclear emissions. ✘
• C. β and X-rays: X-rays are not nuclear emissions. ✘
• D. "λ-rays" and X-rays: this is almost certainly a misprint for γ-rays (λ is the symbol for wavelength or decay constant), and X-rays are still not emitted. ✘

Option A is the only one in which both radiations are true products of natural radioactivity.

Answer: A

Tip: Remember "α, β, γ" for natural radioactivity, and link X-rays to electrons and an X-ray tube. If an option contains X-rays, it is usually a distractor in radioactivity questions.