Home / iGCSE / Coordinated Sciences / C12.4 Separation and purification Paper 1 |IITIAN ACADEMY

CIE iGCSE Co-Ordinated Science C12.4 Separation and purification Exam Style Questions Paper 1

CIE iGCSE Co-Ordinated Science Paper 1 - All Chapters

Question

Sodium chloride is dissolved in water.

Which word describes the water used in this process?

A. solvent
B. solution
C. solute
D. sediment

▶️ Answer/Explanation

When sodium chloride is dissolved in water, two key terms are used:

  • Solvent: The substance that dissolves the solute. In this case, water dissolves the sodium chloride, so water is the solvent.
  • Solute: The substance that is dissolved. Sodium chloride is the solute.
  • Solution: The homogeneous mixture formed when the solute dissolves in the solvent. The resulting mixture (salt water) is the solution.
  • Sediment: Solid particles that settle at the bottom of a liquid. No sediment is formed here because sodium chloride dissolves completely.

Therefore, the correct term for the water is solvent.

✅ Answer: (A)

Question

Copper sulfate is made when copper carbonate is added to dilute sulfuric acid.

The copper carbonate is added until no more carbon dioxide is given off.

The mixture is ……1…… to remove excess copper carbonate.

The resulting solution is then ……2…… to decrease the volume.

This solution is then ……3…… to allow the formation of pure copper sulfate crystals.

Which words complete gaps 1, 2 and 3?

▶️ Answer/Explanation

This question describes the preparation of a soluble salt (copper sulfate) by adding an excess insoluble metal carbonate (copper carbonate) to dilute sulfuric acid.

Step 1: The mixture is filtered to remove the excess unreacted copper carbonate. The filtrate is the copper sulfate solution. (Boiling would not remove the solid).

Step 2: The filtrate is then heated to evaporate some of the water, decreasing the volume and making the solution more concentrated (saturated). (Cooling at this stage would not decrease the volume).

Step 3: The concentrated solution is then left to cool. As it cools, the solubility of copper sulfate decreases, and pure copper sulfate crystals form. (Evaporating to dryness would give a powder, not well-formed crystals, and could decompose the hydrated salt).

Therefore, the correct sequence is filtered, heated, left to cool, which matches row D.

✅ Answer: (D)

Question

When aqueous copper(II) sulfate reacts with aqueous sodium hydroxide, a blue precipitate forms.

Which method is used to remove the precipitate from the reaction mixture?

A. chromatography
B. distillation
C. filtration
D. crystallisation

▶️ Answer/Explanation
Filtration is used to separate an insoluble solid (precipitate) from a liquid. The blue precipitate of copper(II) hydroxide can be separated from the reaction mixture by filtering through filter paper. Chromatography separates dissolved substances, distillation separates liquids based on boiling points, and crystallisation forms solid crystals from a solution.
✅ Answer: (C)

Question

A sample of water contains two useful substances, insoluble chalk and a soluble salt.
Which two processes are used to individually separate the insoluble chalk from the soluble salt and from the water?

A. distillation and chromatography
B. distillation and crystallisation
C. filtration and chromatography
D. filtration and crystallisation

▶️ Answer/Explanation
Filtration separates the insoluble chalk from the water and dissolved salt, since chalk does not pass through the filter paper.
Crystallisation then separates the dissolved soluble salt from the filtrate by evaporating the water until crystals form.
Chromatography and distillation are not suited to isolating a solid salt in crystal form from this mixture.
✅ Answer: (D)

Question

An aqueous salt solution contains an insoluble impurity.

Which processes are used to obtain pure salt crystals?

A. distillation then crystallisation
B. distillation then chromatography
C. filtration then crystallisation
D. filtration then chromatography

▶️ Answer/Explanation
Filtration is used first to remove the insoluble impurity from the salt solution.
The filtrate (pure salt solution) is then evaporated/crystallised to obtain pure salt crystals.
✅ Answer: (C)
More CIE iGCSE Co-Ordinated Science Paper 1 Questions..
Scroll to Top