The radioactive isotope sodium-24 (1124Na^{24}_{11}\text{Na}1124Na) decays by β\betaβ-particle emission to an isotope of magnesium (Mg).
Complete the nuclide equation that represents this decay.
1124Na→…………Mg+…………β ^{24}_{11}\text{Na} \rightarrow {}^{\dots\dots}_{\dots\dots}\text{Mg} + {}^{\dots\dots}_{\dots\dots}\beta 1124Na→…………Mg+…………βA radiation detector is placed on a bench in a laboratory where there are no artificial sources of radiation. The detector is switched on. In six one-minute periods, the detector displays these readings:
18,15,17,16,14,16 18, \quad 15, \quad 17, \quad 16, \quad 14, \quad 16 18,15,17,16,14,16Explain why, in the absence of any artificial source, there are readings on the detector. Suggest one origin of this effect.
Explain why the readings obtained are not all the same.
The half-life of sodium-24 is 15 hours. A sample of sodium-24 is brought close to the detector and in one minute, the reading displayed is 592. The equipment is left in the same place for exactly 45 hours. Predict the reading in a one-minute period at the end of this time.
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.