Why can phosphate rock not be used directly as a fertiliser?
It contains too much calcium for plants to absorb
It is insoluble in water, so plants cannot absorb it
It is too acidic for the roots of plants to absorb
It contains no nitrogen, so plants cannot absorb it
39 exam-style questions on AQA GCSE Chemistry 10.4 The Haber process and the use of NPK fertilisers, covering 10.4.1a The Haber process, 10.4.1b Equilibrium and rate in the Haber process, and 10.4.2 Production and uses of NPK fertilisers. Each one has a worked solution and a mark scheme showing where the marks go.