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MODULE 3
INDUSTRY AND THE ENVIRONMENT
3. (a) In industrial laboratories, the cadmium reduction method is widely used, instead of the
chemical tests that are normally used in school laboratories, to determine if nitrate ions DO NOT WRITE IN THIS AREA
are present as a pollutant in water samples.
(i) Give TWO sources of nitrate ions in water.
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[2 marks]
(ii) Describe a chemical test that is often used in school laboratories to detect the
presence of aqueous nitrate ions.
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[2 marks] DO NOT WRITE IN THIS AREA
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(iii) State ONE ion that cannot be distinguished from the NO by the chemical test
3
that you described in 3 (a) (ii) above.
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[1 mark]
(iv) Suggest ONE possible reason why the laboratory test that you described in
3 (a) (ii), for the determination of nitrate ions as a pollutant in water samples, is
not as appropriate as the cadmium reduction method.
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[2 marks] DO NOT WRITE IN THIS AREA
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