Home / iGCSE Chemistry 0620 Extended – 7.3 Preparation of salts- Exam Style Questions Paper 2

iGCSE Chemistry 0620 Extended - 7.3 Preparation of salts- Exam Style Questions Paper 2- New Syllabus

iGCSE Chemistry MCQ (Extended) Paper 2 - All Chapters

Question

A student adds different solid salts to an excess of water. The student stirs the mixtures to determine the solubilities of the salts.

The results are shown.

What could the four different salts be?

▶️ Answer/Explanation

Correct Answer: B

Explanation: Solubility rules:
– Ammonium nitrate: soluble (all ammonium salts are soluble).
– Sodium carbonate: soluble (all sodium salts are soluble).
– Calcium sulfate: slightly soluble/insoluble (sulfates except Ba, Ca, Pb are soluble; calcium sulfate is sparingly soluble).
– Lead(II) chloride: insoluble (chlorides are soluble except lead and silver).

✅ Option B correctly matches the solubility observations from the diagram.

Question

The formulae of two hydrated salts are shown.

CuSO₄ • xH₂O
CoCl₂ • yH₂O

What are the values of x and y?

▶️ Answer/Explanation
This is a recall question about common hydrated salts. Copper(II) sulfate crystals are well known to be hydrated with 5 water molecules, giving the formula CuSO₄·5H₂O, so x = 5. Cobalt(II) chloride crystals are hydrated with 6 water molecules, forming CoCl₂·6H₂O, meaning y = 6. So the correct pair of values is x = 5 and y = 6.
✅ Answer: (B)

Question

Which method is used to prepare a pure, dry sample of lead(II) chloride?

A. mix aqueous lead(II) nitrate and dilute hydrochloric acid → filter → crystallise and dry the filtrate
B. mix aqueous lead(II) nitrate and dilute hydrochloric acid → filter → wash and dry the residue
C. mix solid lead(II) hydroxide and aqueous sodium chloride → filter → crystallise and dry the filtrate
D. mix solid lead(II) hydroxide and aqueous sodium chloride → filter → wash and dry the residue

▶️ Answer/Explanation
Lead(II) chloride is insoluble in cold water. It is prepared by a precipitation reaction. When mixing solutions of lead(II) nitrate and dilute hydrochloric acid, a white precipitate of lead(II) chloride forms. This is filtered, and the residue (the precipitate) is washed with distilled water and dried.
✅ Answer: (B)
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