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IGCSE · Practice questions · Tests for anions and cations

Name the ions.

Six original Cambridge-style questions on identifying anions and cations from test results.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Reagent, observation, ion.

01
Recall
[3 marks]

Describe a test for chloride ions in a solution. Give the result.

  • Acidify the solution with dilute nitric acid. ✓
  • Add aqueous silver nitrate. ✓
  • A white precipitate forms. ✓
02
Recall
[3 marks]

Describe how to show that a solid contains carbonate ions.

  • Add dilute acid (for example hydrochloric acid). ✓
  • Effervescence (fizzing) is seen. ✓
  • Bubble the gas through limewater, which turns milky, showing carbon dioxide. ✓
03
Analysis
[3 marks]

Solution J gives a green precipitate with aqueous sodium hydroxide. The precipitate does not dissolve in excess. With acidified aqueous barium nitrate it gives a white precipitate. Identify J.

  • Green precipitate insoluble in excess NaOH: iron(II) ions, Fe2+ (chromium(III) would dissolve in excess). ✓
  • White precipitate with barium nitrate: sulfate ions. ✓
  • J is iron(II) sulfate, FeSO4. ✓
04
Analysis
[2 marks]

Two white solids each give a white precipitate with aqueous sodium hydroxide that dissolves in excess. Describe a test to tell aluminium ions from zinc ions.

  • Add aqueous ammonia, then excess. ✓
  • Zinc: white precipitate dissolves in excess ammonia. Aluminium: white precipitate does not dissolve. ✓
05
Recall
[3 marks]

Describe how to carry out a flame test, and give the flame colours for lithium, calcium and barium ions.

  • Clean a nichrome wire in concentrated hydrochloric acid, dip it in the solid and hold it in a hot (blue) Bunsen flame. ✓
  • Lithium: red. Calcium: orange-red. ✓
  • Barium: light green. ✓
06
Explain
[2 marks]

Describe the test for ammonium ions and explain the result.

  • Add aqueous sodium hydroxide and warm gently. ✓
  • Ammonia gas is given off, which turns damp red litmus paper blue. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.