O-LevelChemistryAcids, Bases & Salts5070/11 · Oct/Nov 2018 · Q201 Mark

Three separate mixtures of a solution and a solid are made, as shown in the table. The mixtures are warmed. In which mixtures does gas form?

ANaOH(aq) and NH₄Cl(s): ✓, H₂SO₄(aq) and NH₄Cl(s): ✓, H₂SO₄(aq) and Mg(s): X

BNaOH(aq) and NH₄Cl(s): ✓, H₂SO₄(aq) and NH₄Cl(s): X, H₂SO₄(aq) and Mg(s): ✓

CNaOH(aq) and NH₄Cl(s): X, H₂SO₄(aq) and NH₄Cl(s): ✓, H₂SO₄(aq) and Mg(s): X

DNaOH(aq) and NH₄Cl(s): X, H₂SO₄(aq) and NH₄Cl(s): X, H₂SO₄(aq) and Mg(s): ✓

✓ Correct answer

B: NaOH(aq) and NH₄Cl(s): ✓, H₂SO₄(aq) and NH₄Cl(s): X, H₂SO₄(aq) and Mg(s): ✓

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Topic: Acids, Bases & Salts, O-Level Chemistry (syllabus 5070). Multiple choice, 1 mark.
Source: O-Level Chemistry, Oct/Nov 2018 Paper 1 Variant 1, question 20.

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