Question

12a(i) State two similarities associated with alpha (α), beta (β) particles and gamma (γ) rays. (ii) Define natural radioactivity. (iii) Write a general equation for alpha decay, where X is the parent nucleus and Y represents the daughter nuclide. (iv) Mention one example of natural radioactivity.

Accepted Answer

(i) Similarities: they can cause biological damage to body cells; they can penetrate materials (to varying extents); they are all emitted by radioactive materials.
(ii) Natural radioactivity is the spontaneous disintegration/decay of an unstable atomic nucleus, with the emission of alpha, beta and/or gamma radiation (singly or in combination), accompanied by a release of energy.
(iii) Alpha decay: ᴬₓX → ⁴₂He + ᴬ⁻⁴ₓ₋₂Y.
(iv) Example: Uranium–238 decaying into Thorium–234 (²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He); or Radium–226 decaying into Radon–222.

WAEC Physics 2025 Theory — Question 25

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