State symbols - AQA GCSE Chemistry Exam Questions

Practise 15 exam-style questions on State symbols for AQA GCSE Chemistry. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.

15 questions
1–5 marks each
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15 questions, marked as you go

Sample questions with model answers

Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.

Question 1

2 marks

Magnesium ribbon reacts with dilute hydrochloric acid to produce magnesium chloride solution and hydrogen gas. The equation is:
Mg + 2HCl → MgCl₂ + H₂

Rewrite the equation with state symbols.

Model answer

Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

Explanation

Magnesium is a solid metal, dilute hydrochloric acid is hydrogen chloride dissolved in water, and the magnesium chloride produced stays dissolved. Hydrogen is a gas, seen as bubbles.

Mark scheme

1 mark
Mg(s) and 2HCl(aq)
both needed
1 mark
MgCl₂(aq) and H₂(g)
both needed

Question 2

2 marks

A student adds a strip of zinc to copper sulfate solution. The student writes this equation:
Zn(aq) + CuSO₄(s) → ZnSO₄(aq) + Cu(s)

Two of the state symbols are wrong. Identify the two wrong state symbols and give the correct ones.

Model answer

Zinc is a solid metal strip, so it should be Zn(s). The copper sulfate is a solution, so it should be CuSO₄(aq).
Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)

Explanation

Read the description of the reaction carefully: the metal is added as a solid and the copper sulfate is a solution. In a displacement reaction the metal displaced (copper) forms as a solid, and the new salt stays dissolved.

Mark scheme

1 mark
zinc should be Zn(s)
1 mark
copper sulfate should be CuSO₄(aq)
if more than two changes are made, deduct 1 mark for each incorrect change

Question 3

3 marks

When green copper carbonate powder (CuCO₃) is heated strongly, it decomposes into black copper oxide and carbon dioxide.

Write a balanced symbol equation, with state symbols, for this reaction. Use the state symbols to explain why the mass of the solid decreases.

Model answer

CuCO₃(s) → CuO(s) + CO₂(g)
One product, carbon dioxide, is a gas, so it escapes from the container into the air. Only the copper oxide is left as a solid, so the mass of solid decreases.

Explanation

Mass is conserved in the reaction, but a gaseous product escapes from an open container, so the measured mass falls. State symbols make this easy to spot: look for (g) on the products side.

Mark scheme

1 mark
CuCO₃ → CuO + CO₂
1 mark
CuCO₃(s) → CuO(s) + CO₂(g)
all three state symbols correct
1 mark
carbon dioxide is a gas (g) so it escapes into the air, leaving less mass of solid
allow 'one of the products is a gas which is lost'

Question 4

4 marks

Marble chips (calcium carbonate, CaCO₃) react with dilute hydrochloric acid. The products are calcium chloride solution, water and carbon dioxide.

Write a balanced symbol equation, with state symbols, for this reaction.

Model answer

CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g)

Explanation

Two hydrochloric acid units are needed because calcium chloride has two chloride ions. Marble is a solid, calcium chloride is soluble so it is (aq), water is (l), and carbon dioxide is given off as a gas.

Mark scheme

1 mark
CaCO₃ + HCl → CaCl₂ + H₂O + CO₂ (correct formulae)
1 mark
balanced: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
allow multiples
1 mark
CaCO₃(s) and HCl(aq)
1 mark
CaCl₂(aq), H₂O(l) and CO₂(g)
all three needed

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