Relative atomic masses (ArA_rAr): H=1\text{H} = 1H=1 N=14\text{N} = 14N=14 O=16\text{O} = 16O=16 Ca=40\text{Ca} = 40Ca=40
Which compound has the greatest percentage by mass of oxygen?
CaO\text{CaO}CaO
Ca(OH)2\text{Ca(OH)}_2Ca(OH)2
Ca(NO3)2\text{Ca(NO}_3\text{)}_2Ca(NO3)2
H2O\text{H}_2\text{O}H2O
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.