For CH4+2O2→CO2+2H2O\mathrm{CH_4+2O_2\rightarrow CO_2+2H_2O}CH4+2O2→CO2+2H2O, which reactant bonds must be included in a bond-energy calculation?
Four C-C bonds and two O-H bonds
One C-H bond and one O-O bond
Two C=O bonds and four O-H bonds
Four C-H bonds and two O=O bonds
94 exam-style questions on Edexcel GCSE Chemistry 8.2 Heat energy changes in chemical reactions, covering 8.2.1 Exothermic and endothermic changes, 8.2.2 Bond breaking, bond making and overall energy change, 8.2.3 Calculating energy change from bond energies, and 8.2.4 Activation energy and reaction profiles. Each one has a worked solution and a mark scheme showing where the marks go.