OxfordAQA International GCSE Chemistry: Transition metals (9202) – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions cover section 3.7.2 Transition metals (statements a and b) of the OxfordAQA International GCSE Chemistry (9202) specification, Version 6.2, for exams May/June 2018 onwards. The qualification is not tiered. Some questions also use 3.4.3 (ion tests) and 3.8 (catalysts). Questions 8, 10 and 11 are longer.

Learn the content in the Transition metals study guide and the Transition metals revision notes. Free diagnostics help you decide what to revise next.

Use these values where needed: Aᵣ Fe = 56, S = 32, O = 16.

Questions

1. A student writes: “Transition metals are found between Groups 3 and 4. All of them form ions with only one charge and colourless compounds.”

Rewrite the student’s statement so that it is correct, and add the third typical property of transition metals. [3]

2. The table gives data for five metals. Use these values.

Metal	Melting point / °C	Density / g/cm³
A	1246	7.2
B	28	1.93
D	−39	13.5
G	39	1.53
J	1910	6.0

Three of the metals are transition metals and two are Group 1 metals.

(a) Identify the three transition metals. Give a reason based on the data. [2] (b) Explain why metal D could be wrongly placed in Group 1 if only melting points were used. [2]

3. This question is about the charges on transition metal ions.

(a) Give the charge on the metal ion in each compound: Co₂O₃, NiCO₃, Cr(NO₃)₃. [3] (b) Write the formula of cobalt(II) hydroxide. [1] (c) Iron forms both FeSO₄ and Fe₂(SO₄)₃. State which typical property of transition metals this shows. [1]

4. Three unlabelled bottles contain copper(II) nitrate, iron(III) sulfate and magnesium chloride solutions. A few drops of sodium hydroxide solution are added to a sample of each.

(a) Give the colour of the precipitate formed by each solution. [3] (b) Write the ionic equation for the reaction of copper(II) ions with hydroxide ions. [2] (c) One solution is colourless. Identify it and explain why its colour is different from the other two. [1]

5. A freshly cut piece of lithium and a freshly polished nickel coin are left side by side on a bench for ten minutes.

(a) Predict how the surface of each metal will look after ten minutes. Explain the difference. [2] (b) The lithium is then placed in cold water. Give two observations. [2] (c) Write a balanced symbol equation for the reaction in (b). [2]

6. A rectangular block of an unknown metal measures 2.0 cm × 2.0 cm × 1.5 cm and has a mass of 27.0 g.

(a) Calculate the density of the metal. Give the unit. [2] (b) Suggest whether the metal is more likely to be a transition metal or a Group 1 metal. Give a reason. [1]

7. Four catalysts that appear in this course are iron, vanadium(V) oxide, phosphoric acid and the enzymes in yeast.

(a) Identify the two catalysts that contain a transition metal. [2] (b) Give the charge on the vanadium ion in V₂O₅. [1] (c) Vanadium(V) oxide is the catalyst in the reaction 2SO₂ + O₂ ⇌ 2SO₃. Explain why V₂O₅ is not written as a reactant in the equation. [1] (d) A student says that adding more vanadium(V) oxide will increase the amount of sulfur trioxide formed. Explain whether the student is correct. [1]

8. A car’s catalytic converter has a thin coating of platinum and rhodium, two transition metals, on a honeycomb support. On a test bench, the engine makes 9.6 g of carbon monoxide per minute. With the converter warmed up, 0.48 g of carbon monoxide per minute leaves the exhaust pipe.

(a) Calculate the percentage of the carbon monoxide that the converter removes. [2] (b) In the converter, carbon monoxide reacts with oxygen to form carbon dioxide. Give the balanced symbol equation. [2] (c) Explain why the metals are spread as a thin coating rather than used as solid lumps. [2] (d) After many years of use, the mass of platinum in the converter is almost unchanged. Explain what this shows about the platinum. [1]

9. An engineer needs a metal for a valve that works at 900 °C in moist air and must not bend. Use the information in the table.

Metal	Melting point / °C	Hardness	With water
L	1668	hard	none seen
M	98	soft; easily sliced	gives off hydrogen rapidly
N	−39	liquid at room temperature	none seen

(a) Choose the most suitable metal. Explain why each of the other two is unsuitable. [4] (b) Two of the metals are transition metals. Identify them. [1]

10. Use the data and your own knowledge to compare tungsten with rubidium. Use these values: tungsten melts at 3422 °C and has a density of 19.3 g/cm³; rubidium melts at 39 °C and has a density of 1.53 g/cm³. [6]

11. This question is about iron.

(a) Write the formula of iron(III) oxide. [1] (b) Calculate the percentage by mass of iron in iron(II) sulfate, FeSO₄. [2] (c) Describe a test, with the expected results, that would tell iron(II) sulfate solution apart from iron(III) sulfate solution. [2] (d) Write a balanced symbol equation for the reaction in the Haber process. [1] (e) The Haber process runs at about 450 °C. Explain why solid iron can be used as the catalyst, but sodium, a Group 1 metal that melts at 98 °C, could not be used in the same way. [2]

Answers

1. Transition metals are found between Groups 2 and 3 [1]. Many of them form ions with different charges and form coloured compounds [1]. Many are useful as catalysts [1]. Examiner insight: Answers that keep the word “all” usually lose credit; the specification’s wording is “many”.

2. (a) A, D and J [1]. Their densities (6.0 to 13.5 g/cm³) are much higher than those of B and G (below 2 g/cm³) [1]. (b) D melts at −39 °C, which is lower than both Group 1 metals in the table [1]. D is like mercury: a transition metal that is the exception to the high melting point pattern, but its high density shows it is a transition metal [1]. Examiner insight: In (a) quote or compare the data; “they are denser” with no reference to the figures for B and G is weaker than an answer that uses the values.

3. (a) Co₂O₃: 3+ [1]; NiCO₃: 2+ [1]; Cr(NO₃)₃: 3+ [1]. (b) Co(OH)₂ [1] (c) Transition metals form ions with different charges (Fe²⁺ and Fe³⁺) [1]. Examiner insight: Check charge balance before you write a formula; Co(OH) or CoOH₂ for cobalt(II) hydroxide does not balance and is unlikely to gain credit.

4. (a) Copper(II) nitrate: blue [1]. Iron(III) sulfate: brown [1]. Magnesium chloride: white [1]. (b) Correct formulae Cu²⁺ + OH⁻ → Cu(OH)₂ [1]; balanced: Cu²⁺ + 2OH⁻ → Cu(OH)₂ [1]. (c) Magnesium chloride; magnesium is in Group 2, not a transition metal, so its compounds are white or colourless [1]. Examiner insight: Give a single colour for each precipitate; “blue-green” or “brown or green” hedges between two answers and usually gains nothing.

5. (a) The lithium goes dull as an oxide layer forms quickly [1]. The nickel stays shiny, because it is much less reactive with oxygen [1]. (b) Any two: fizzing or bubbles; floats; moves about on the surface; gets smaller [1] [1]. (c) Correct formulae Li + H₂O → LiOH + H₂ [1]; balanced: 2Li + 2H₂O → 2LiOH + H₂ [1]. Examiner insight: “Hydrogen is produced” names a product rather than describing what you see; write “fizzing” or “bubbles”.

6. (a) Volume = 2.0 × 2.0 × 1.5 = 6.0 cm³ [1]. Density = 27.0 ÷ 6.0 = 4.5 g/cm³ [1]. (b) Transition metal: its density is far above those of lithium to caesium, which are all below 2 g/cm³ [1]. Examiner insight: A bare 4.5 without g/cm³ may not be credited when the question asks for the unit.

7. (a) Iron [1] and vanadium(V) oxide [1]. (b) Five O²⁻ give 10−, shared by two vanadium ions: 5+ [1]. (c) V₂O₅ is unchanged at the end, so it is neither a reactant nor a product [1]. (d) Not correct: a catalyst changes the rate, so sulfur trioxide forms faster, but it does not increase the amount formed [1]. Examiner insight: In (a), adding phosphoric acid or yeast enzymes to the two correct answers contradicts them; give exactly the two asked for.

8. (a) Mass removed = 9.6 − 0.48 = 9.12 g per minute [1]. Percentage removed = 9.12 ÷ 9.6 × 100 = 95.0% [1]. (b) Correct formulae CO + O₂ → CO₂ [1]; balanced: 2CO + O₂ → 2CO₂ [1]. (c) A thin coating gives a larger surface area, so gas particles collide with the catalyst more often and react faster [1]. Less of these expensive metals is needed [1]. (d) The platinum is not used up, so it is acting as a catalyst [1]. Examiner insight: In (a), 0.48 ÷ 9.6 × 100 = 5.0% is the percentage that escapes, not the percentage removed; check which one the question asks for.

9. (a) Metal L [1]. Its melting point (1668 °C) is well above 900 °C, it is hard, and it does not react with water [1]. M would melt (98 °C), is soft and reacts with water in moist air [1]. N is a liquid, so it cannot hold its shape as a valve [1]. (b) L and N [1]. Examiner insight: Give a reason from the table for rejecting each other metal; “M and N are unsuitable” alone justifies nothing.

10. Any six comparisons, one mark each:

• Tungsten has a much higher melting point: 3422 − 39 = 3383 °C higher [1].
• Tungsten is much denser: 19.3 ÷ 1.53 ≈ 13, so about 13 times as dense [1].
• Tungsten is stronger than rubidium [1].
• Tungsten is harder; rubidium is soft enough to cut with a knife [1].
• Rubidium reacts vigorously with cold water, releasing hydrogen; tungsten does not [1].
• Rubidium tarnishes rapidly in air; tungsten reacts with oxygen far less vigorously [1].
• A general statement that tungsten is much less reactive than rubidium can replace one missing point.

Examiner insight: Six separate comparisons are needed; describing rubidium’s reaction with water twice in different words counts as one point.

11. (a) Fe₂O₃ [1]. (b) Mᵣ = 56 + 32 + 4 × 16 = 152 [1]. Percentage of iron = 56 ÷ 152 × 100 = 36.8% [1]. (c) Add sodium hydroxide solution to each [1]. Iron(II) sulfate gives a green precipitate; iron(III) sulfate gives a brown precipitate [1]. (d) N₂ + 3H₂ ⇌ 2NH₃ [1]. (e) Iron’s melting point is far above 450 °C, so it stays solid in the reactor [1]. Sodium would be a liquid at 450 °C, so it could not stay in place as a solid catalyst [1]. Examiner insight: In (b) set out the Mᵣ of 152 before dividing, so the examiner can follow your method even if the last step slips.

Where marks are usually lost

• Writing “all transition metals” for the three typical properties.
• Forgetting mercury, or applying its exception to density.
• Ionic equations with the wrong number of hydroxide ions.
• Saying a catalyst increases the amount of product rather than the rate.
• Confusing the percentage removed with the percentage left.
• “Compare” answers that describe one metal only.

Next steps

• Transition metals revision notes
• Transition metals study guide
• Metals practice questions for the reactivity series
• OxfordAQA International GCSE Chemistry hub
• Printable checklist
• Try all free 10-minute diagnostics.
• Book a free trial class.

Official syllabus

OxfordAQA International GCSE Chemistry (9202) specification, Version 6.2, for exams May/June 2018 onwards, published by OxfordAQA. Section 3.7.2 Transition metals, statements a and b.