O Level / IGCSE Chemistry chapter 12: Experimental techniques and chemical analysis MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

88 exam-style questions on Experimental techniques and chemical analysis, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

88 questions · 4 topics · 10 per test

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What chapter 12 covers

Ten Experimental techniques and chemical analysis questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. Salt is to be obtained from a mixture of salt and sand. Which sequence of steps is correct?

  1. A
    distil the dry mixture and collect the salt in the condenser
  2. B
    filter the dry mixture and collect the salt from the filtrate
  3. C
    add water, stir, filter, then evaporate the filtrate to crystallise
  4. D
    add water, evaporate, then filter off the salt
Show answer

Answer: C. Salt dissolves but sand does not. Filtering removes the sand; the salt is then recovered from the filtrate.

2. Magnesium ribbon is added to dilute hydrochloric acid and a colourless gas is given off. Which test confirms the gas?

  1. A
    it relights a glowing splint
  2. B
    it turns limewater milky
  3. C
    it turns acidified potassium manganate(VII) colourless
  4. D
    it burns with a squeaky pop when a lighted splint is held near
Show answer

Answer: D. A metal and an acid give hydrogen, which burns with a pop near a lighted splint. Relighting a glowing splint is the test for oxygen.

3. Aqueous sodium hydroxide is added to a solution. A green precipitate forms which does not dissolve in excess. Which cation is present?

  1. A
    Fe3+
  2. B
    Fe2+
  3. C
    Cu2+
  4. D
    Cr3+
Show answer

Answer: B. Iron(II) hydroxide is green and insoluble in excess. Chromium(III) gives a green precipitate that dissolves in excess; Fe3+ gives red-brown and Cu2+ light blue.

4. The volume of gas made in a reaction is measured by collecting it over water in an upturned measuring cylinder. For which gas would this method give a volume that is much too low, so that a gas syringe should be used instead?

  1. A
    ammonia
  2. B
    hydrogen
  3. C
    methane
  4. D
    oxygen
Show answer

Answer: A. Ammonia is very soluble in water, so much of it dissolves and the volume collected is far too low. Hydrogen, methane and oxygen are only slightly soluble.

5. 25.0 cm3 of 0.200 mol/dm3 aqueous sodium hydroxide is neutralised by 12.5 cm3 of dilute sulfuric acid: H2SO4 + 2NaOH → Na2SO4 + 2H2O. What is the concentration of the sulfuric acid?

  1. A
    0.100 mol/dm3
  2. B
    0.200 mol/dm3
  3. C
    0.400 mol/dm3
  4. D
    0.800 mol/dm3
Show answer

Answer: B. Moles NaOH = 0.00500 mol, so moles H2SO4 = 0.00250 mol; 0.00250 ÷ 0.0125 = 0.200 mol/dm3. Ignoring the 1 : 2 ratio gives 0.400 mol/dm3.

6. Why does an Rf value have no units?

  1. A
    It is measured in centimetres, which are left out by convention.
  2. B
    It is a ratio of two distances, so the units cancel.
  3. C
    It is a number of particles.
  4. D
    It depends only on the colour of the spot.
Show answer

Answer: B. Rf = distance moved by substance ÷ distance moved by solvent; both are lengths, so the units cancel.

7. Which pair of results is correct for a sample of potassium iodide?

  1. A
    flame colour lilac; yellow precipitate with acidified silver nitrate
  2. B
    flame colour lilac; cream precipitate with acidified silver nitrate
  3. C
    flame colour yellow; yellow precipitate with acidified silver nitrate
  4. D
    flame colour red; white precipitate with acidified silver nitrate
Show answer

Answer: A. Potassium ions give a lilac flame; iodide ions give a yellow precipitate of silver iodide. A yellow flame is sodium, and cream is bromide.

8. A gas relights a glowing splint. Which gas is it?

  1. A
    ammonia
  2. B
    carbon dioxide
  3. C
    oxygen
  4. D
    hydrogen
Show answer

Answer: C. Oxygen relights a glowing splint; hydrogen pops with a lit splint; carbon dioxide turns limewater milky; ammonia turns damp red litmus blue.

9. In paper chromatography, what is the Rf value of a spot?

  1. A
    the time taken
  2. B
    distance moved by solvent ÷ distance moved by spot
  3. C
    distance moved by spot ÷ distance moved by solvent
  4. D
    the height of the paper
Show answer

Answer: C. Rf = distance moved by the substance ÷ distance moved by the solvent front; it is always between 0 and 1 for a given solvent.

10. Aqueous ammonia is added to copper(II) sulfate solution. A light blue precipitate forms, which dissolves in excess to give a deep blue solution. Which ion does this identify?

  1. A
    Al3+
  2. B
    Cu2+
  3. C
    Fe2+
  4. D
    Zn2+
Show answer

Answer: B. Copper(II) hydroxide is light blue; in excess ammonia it dissolves to form a deep blue complex. This distinguishes Cu2+ from Zn2+, whose white precipitate also dissolves but colourlessly.

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Ways to practise this chapter

Experimental techniques and chemical analysis: questions students ask

How many Experimental techniques and chemical analysis MCQs are there?

88, each with the answer and a short explanation, across 4 topics: Experimental design, Chromatography, Separation and purification, Identification of ions and gases. Every chapter test draws ten of them, so you can take it many times.

Is the O Level / IGCSE Chemistry chapter 12 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

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