Thorium-228 (90228Th^{228}_{90}\text{Th}90228Th) is a radioactive isotope that decays via alpha emission.
Complete the decay equation for Thorium-228 by determining the missing mass number AAA and atomic number ZZZ for Radium (Ra\text{Ra}Ra):
90228Th→ZARa+24He ^{228}_{90}\text{Th} \to ^{A}_{Z}\text{Ra} + ^{4}_{2}\text{He} 90228Th→ZARa+24HeExplain why alpha-emitting radioactive substances pose an extreme danger when inside the body (internal contamination), despite being relatively harmless when located outside the body.
A sample of this radioactive isotope was left to decay. After 12 hours12\text{ hours}12 hours, the mass of Thorium-228 remaining in the sample was found to be 1.875×10−6 g1.875 \times 10^{-6}\text{ g}1.875×10−6 g. The half-life of this isotope is 3 hours3\text{ hours}3 hours. Calculate the initial mass of the sample.
6 exam-style questions on AQA GCSE Physics 4.2 Atoms and nuclear radiation, covering 4.2.1 Radioactive decay and nuclear radiation, 4.2.2 Nuclear equations, 4.2.3 Half-lives and the random nature of radioactive decay, and 4.2.4 Radioactive contamination. Each one has a worked solution and a mark scheme showing where the marks go.