The chemical symbol for radium is Ra\text{Ra}Ra and for radon is Rn\text{Rn}Rn. The following nuclear equation represents the radioactive decay of radium-226:
88226Ra→yxRn+24He {}^{226}_{88}\text{Ra} \rightarrow {}^{x}_{y}\text{Rn} + {}^{4}_{2}\text{He} 88226Ra→yxRn+24HeWhat are the numbers x x\,x and yyy?
x=222x = 222x=222, y=90y = 90y=90
x=222x = 222x=222, y=86y = 86y=86
x=230x = 230x=230, y=90y = 90y=90
x=230x = 230x=230, y=86y = 86y=86
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.