The unstable nucleus of an isotope undergoes radioactive decay. During this process, the nucleon number (mass number) of the nucleus decreases by 4 and its proton number (atomic number) decreases by 2.
Which description of this radioactive decay event is correct?
The nucleus emits an α\alphaα-particle.
The nucleus emits a β−\beta^-β−-particle.
The nucleus emits γ\gammaγ-radiation.
The nucleus emits a positron (β+\beta^+β+-particle).
484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.