Strontium-90 (3890Sr\text{}^{90}_{38}\text{Sr}3890Sr) is radioactive. It decays by β\betaβ-emission to form an isotope of yttrium (Y\text{Y}Y).
Complete the nuclide equation for this decay:
3890Sr→ ......Y+ ......β \text{}^{90}_{38}\text{Sr} \rightarrow \:\: ^{...}_{...}\text{Y} + \:\: ^{...}_{...}\beta 3890Sr→......Y+......βA pure sample of strontium-90 emits β\betaβ-particles at an initial count rate of 3200 counts/second3200\text{ counts/second}3200 counts/second. The half-life of strontium-90 is 28 years28\text{ years}28 years.
Calculate the count rate from the emission of β\betaβ-particles from the strontium in the sample after 112 years112\text{ years}112 years have passed.
The isotope of yttrium in (a) is also radioactive. It decays by β\betaβ-emission and has a half-life of 64 hours64\text{ hours}64 hours.
State and explain how this would affect the observed beta count rate for the sample in (b) after 112 years112\text{ years}112 years.
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.