A student writes the nuclide equation for a nuclear fusion reaction.
12H+12H→1AQ+11H ^{2}_{1}\text{H} + ^{2}_{1}\text{H} \rightarrow ^{A}_{1}\text{Q} + ^{1}_{1}\text{H} 12H+12H→1AQ+11HWhat is the missing number A A\,A and the missing element symbol QQQ?
A=3A = 3A=3, Q=HQ = \text{H}Q=H
A=3A = 3A=3, Q=HeQ = \text{He}Q=He
A=4A = 4A=4, Q=HQ = \text{H}Q=H
A=4A = 4A=4, Q=HeQ = \text{He}Q=He
170 exam-style questions on CIE IGCSE Physics 5.1.2a Composition of the nucleus and isotopes. Each one has a worked solution and a mark scheme showing where the marks go.