Which half equation shows an oxidation?
2Br−→Br2+2e−\mathrm{2Br^{-} \rightarrow Br_{2} + 2e^{-}}2Br−→Br2+2e−
Cu2++2e−→Cu\mathrm{Cu^{2+} + 2e^{-} \rightarrow Cu}Cu2++2e−→Cu
Cl2+2e−→2Cl−\mathrm{Cl_{2} + 2e^{-} \rightarrow 2Cl^{-}}Cl2+2e−→2Cl−
Na++e−→Na\mathrm{Na^{+} + e^{-} \rightarrow Na}Na++e−→Na
53 exam-style questions on OCR GCSE Chemistry 3.3 Types of chemical reactions, covering 3.3.1 Oxidation and reduction in terms of oxygen, 3.3.2 Acids, alkalis and neutralisation, 3.3.3 The pH scale and measuring pH, 3.3.4 Oxidation and reduction in terms of electrons, 3.3.5 Dilute and concentrated, weak and strong acids, and 3.3.6 Hydrogen ion concentration and pH. Each one has a worked solution and a mark scheme showing where the marks go.