Chapter One · Iron: practice questions

Cementite, the hard compound formed when iron combines with carbon, has the formula:

• AFe₂C
• BFeC
• CFeCO₃
• DFe₃C

Which of the following chemical formulae correctly represents the ore haematite?

• AFeCO₃
• BFe₃O₄
• CFe₂O₃
• DFeS₂

Galvanising protects iron from rusting by coating its surface with a layer of:

• AZinc
• BChromium
• CCopper
• DTin

How is iron(II) oxide (FeO) prepared by heating iron(II) oxalate?

• AIn the presence of hot air or excess oxygen
• BIn the presence of concentrated sulphuric acid
• CIn the absence of air
• DThrough electrodeposition from a chloride solution

What happens when iron (II) oxide is heated in hot air?

• AIt reduces to pure iron
• BIt converts to magnetic iron oxide
• CIt decomposes into iron and carbon dioxide
• DIt is easily oxidized to iron (III) oxide

A transition element (X) is added to iron to make an alloy that strongly resists rust and dilute acids and is used for surgical instruments. Element (X) is most likely:

• AChromium
• BLead
• CTin
• DSodium

During the roasting process of iron ores, what is the chemical equation and iron percentage resulting from the thermal decomposition of siderite (FeCO3)?

• AFeCO3(s) -> FeO(s) + CO2(g), giving FeO with 69.6% iron
• B2FeCO3(s) + 1/2 O2(g) -> Fe2O3(s) + 2CO2(g), giving 40% iron
• CFeCO3(s) -> Fe(s) + CO3(g), giving 100% iron
• DFeCO3(s) -> FeO(s) + CO2(g), where FeCO3 has 48.5% iron

When 88 g of carbon dioxide passes over white-hot coke near the base of the furnace, CO₂(g) + C(s) → 2CO(g), what mass of carbon monoxide is formed? (C = 12, O = 16)

• A112 g
• B56 g
• C84 g
• D168 g

How does the behavior of concentrated nitric acid on iron differ from that of dilute mineral acids?

• AConcentrated nitric acid produces a mixture of iron(II) and iron(III) salts, whereas dilute acids produce only iron(III) salts.
• BConcentrated nitric acid reacts violently to produce magnetic iron oxide, whereas dilute acids cause passivation.
• CConcentrated nitric acid yields iron(III) chloride, whereas dilute acids yield iron(II) sulphide.
• DConcentrated nitric acid causes passivity due to a protective thin layer of oxide, whereas dilute acids dissolve iron producing iron(II) salts and hydrogen gas.

What is the percentage by mass of iron in the ore siderite, FeCO₃? (Fe = 56, C = 12, O = 16)

• A70.0%
• B46.7%
• C48.3%
• D38.6%