Home / iGCSE Chemistry (0620) Core:12.5 Identification of ions and gases: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core:12.5 Identification of ions and gases: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core Paper 1 - All Chapters
Question

The results of two tests on substance G are listed.

  • A flame test produces a yellow flame.
  • Substance G is added to aqueous sodium hydroxide and powdered aluminium and warmed carefully. A gas is given off which turns damp red litmus paper blue.

What is G?

A) potassium chloride
B) potassium nitrate
C) sodium chloride
D) sodium nitrate

▶️ Answer/Explanation
Solution

Ans: D

Let’s analyze the test results:

1. Flame test (yellow flame):
– Sodium compounds give a persistent yellow flame
– Potassium gives a lilac flame
This suggests the substance contains sodium, eliminating options A and B.

2. NaOH + Al test:
This is the test for nitrates. The gas produced is ammonia (NH3), which turns damp red litmus blue (ammonia is alkaline).
The reaction is: NO3– + Al + OH– + H2O → NH3 + AlO2–

Between the remaining options (C and D):
– Sodium chloride (C) would not give this nitrate test result
– Sodium nitrate (D) fits both the flame test and the nitrate test

Therefore, G must be sodium nitrate (option D).

Question

 Two reactions, M and N, both form carbon dioxide.

$\mathrm{CaCO}_3 \stackrel{\mathrm{M}}{\longrightarrow} \mathrm{CO}_2 \stackrel{\mathrm{N}}{\longleftarrow} \mathrm{CH}_4$

Which types of reaction are M and N?

▶️Answer/Explanation

Ans:B

Question

Which row describes two uses of sulfur dioxide?

▶️Answer/Explanation

Ans:B

Question

Which statement about lime and limestone is correct?

A Calcium oxide is formed from limestone in a displacement reaction.

B Lime is used to treat alkaline soils.

C Limestone is a waste material in the manufacture of iron.

D Slaked lime is used in the process of flue gas desulfurisation.

▶️Answer/Explanation

Ans:D

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