Which equation is balanced?
2Fe+3O2→2Fe2O32\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_32Fe+3O2→2Fe2O3
2Na+2H2O→2NaOH+2H22\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + 2\text{H}_22Na+2H2O→2NaOH+2H2
CH4+O2→CO2+2H2O\text{CH}_4 + \text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}CH4+O2→CO2+2H2O
2Mg+O2→2MgO2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}2Mg+O2→2MgO
40 exam-style questions on AQA GCSE Chemistry 3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations, covering 3.1.1 Conservation of mass and balanced chemical equations, 3.1.2 Relative formula mass, 3.1.3 Mass changes when a reactant or product is a gas, and 3.1.4 Chemical measurements. Each one has a worked solution and a mark scheme showing where the marks go.