Properties of Iron questions

Each of the following is a physical property of iron, except ..........

1. A It conducts electricity less than copper.
2. B It is easy to shape, like copper.
3. C It is denser than manganese.
4. D Its magnetic properties are like those of zinc.

From the following chart:
Which of the following gives (1), (2) and (A)?

1. A (1): reduction , (2): oxidation , (A): FeCl₃
2. B (1): oxidation , (2): reduction , (A): FeCl₂
3. C (1): reduction , (2): oxidation , (A): FeCl₂
4. D (1): oxidation , (2): reduction , (A): FeCl₃

From the following chart:
Which of the following is correct?

1. A (A): black , (B): Fe₂O₃
2. B (B): Fe , (C): Fe₃O₄
3. C (A): red , (C): FeO
4. D (A): FeO , (B): Fe

Hydrogen gas is given off when iron reacts with ..........

1. A steam (at 500°C).
2. B concentrated sulphuric acid (at 400°C).
3. C steam (at 100°C).
4. D concentrated nitric acid (at 200°C).

The metal used as a catalyst in preparing ammonia gas reacts with air under suitable conditions, forming a compound whose chemical formula is ..........

1. A FeO
2. B MnO₂
3. C Fe₃O₄
4. D Mn₂O₃

How many moles of sulphur are needed to react completely with 4 mol of iron?

1. A 2 mol
2. B 4 mol
3. C 6 mol
4. D 8 mol

The compound FeS agrees with the compound ..........

1. A Cu₂Cl₂ in magnetic properties.
2. B ZnO in the possibility of being oxidized.
3. C FeCl₃ in the possibility of preparing it directly from iron.
4. D KMnO₄ in the possibility of using it as a strong oxidizing agent.

The salt produced from the reaction of iron with dilute hydrochloric acid agrees with the salt produced from the reaction of iron with dilute sulphuric acid in each of the following, except that they ............

1. A are paramagnetic substances.
2. B are iron(II) salts.
3. C contain the same number of anions.
4. D dissolve in water.

When iron reacts with substance (1) or with substance (2) under the same reaction conditions, substance (3) is formed.
Which of the following is correct?

1. A (1): air , (2): steam , (3): magnetic iron oxide.
2. B (1): chlorine , (2): hydrochloric acid , (3): iron(II) chloride.
3. C (1): oxygen , (2): carbon dioxide , (3): iron(III) oxide.
4. D (1): steam , (2): ammonium hydroxide , (3): magnetic iron oxide.

Each of the following is a property of iron, except that it ............

1. A does not react with dry air at ordinary temperatures.
2. B does not react with hot concentrated sulphuric acid.
3. C reacts with chlorine gas forming a salt that cannot be oxidized.
4. D reacts with dilute HCl forming a salt that is easily oxidized.

The following chart shows some chemical reactions:
Each of the following is correct, except ..........

1. A The oxidation number of the cation of compound (1) is +3
2. B The oxidation number of the cation of compound (3) is +2
3. C Compound (3) is easily oxidized.
4. D Compound (2) is concentrated nitric acid.

The products of the reaction of iron with dilute and with concentrated acid (X) are different.
What is acid (X), and what is the common product of the two reactions?

1. A Sulphuric acid / SO₂ gas is given off
2. B Sulphuric acid / Fe²⁺ ions are formed
3. C Nitric acid / steam is given off.
4. D Nitric acid / Fe³⁺ ions are formed

From the following oxidation-reduction reactions:
(1): the combustion of coke in the blast furnace.
(2): the reaction of iron(III) oxide with water gas.
(3): the reaction of iron with dilute hydrochloric acid.
What is the substance acting as the oxidizing agent in each of the previous reactions?

1. A (1): C , (2): Fe³⁺ , (3): H⁺
2. B (1): C , (2): CO + H₂ , (3): Fe
3. C (1): O₂ , (2): Fe³⁺ , (3): Fe
4. D (1): O₂ , (2): Fe³⁺ , (3): H⁺

Which of the following is correct when iron reacts with ..........

1. A dilute or hot concentrated sulphuric acid, forming iron(III) sulphate.
2. B the elements sulphur or chlorine, forming the two iron(II) compounds.
3. C steam or oxygen (at 500°C), forming a strong magnet.
4. D dilute or concentrated nitric acid, forming iron(III) nitrate.

Four equal volumes of different acids were added to four identical pieces of iron (each one separately).
Which acid forms a layer of oxide as the final product of the reaction?

1. A Dilute sulphuric acid.
2. B Concentrated sulphuric acid.
3. C Dilute hydrochloric acid.
4. D Concentrated nitric acid.

A piece of iron was dipped in acid (X) for some time. When it was washed with distilled water and moved to a beaker containing dilute HCl solution, gas bubbles were given off after some time.
What is acid (X)?

1. A Dilute sulphuric acid.
2. B Hot concentrated sulphuric acid.
3. C Dilute hydrochloric acid.
4. D Concentrated nitric acid.

From the opposite chart:
Which of the following is correct?

1. A (1): FeO , (2): FeCl₃ , (3): FeCl₂
2. B (1): Fe₃O₄ , (2): FeCl₂ , (3): FeCl₃
3. C (1): Fe₃O₄ , (2): FeCl₃ , (3): FeCl₂
4. D (1): FeO , (2): FeCl₂ , (3): FeCl₃

What processes are carried out, in order, to obtain iron(III) chloride from siderite ore?

1. A Roasting – reduction at 800°C – oxidation.
2. B Oxidation – reduction at 800°C – roasting.
3. C Heating – reduction at 300°C – oxidation.
4. D Reduction at 300°C – oxidation – heating at 800°C

From the following chart:
Which of the following represents iron metal?

1. A (1).
2. B (2).
3. C (3).
4. D (4).

From the following chart:
Which of the following represents iron metal?

1. A (1).
2. B (2).
3. C (3).
4. D (4).

When iron(II) oxalate is heated in air, ............ is produced.

1. A FeO , CO only
2. B Fe₂O₃ , CO₂
3. C FeO , CO , CO₂
4. D Fe₃O₄ , CO₂ , CO

To change limonite into iron(II) oxide, ............ is needed.

1. A roasting then oxidation
2. B roasting then reduction at 600°C
3. C reduction then oxidation
4. D oxidation then reduction at 800°C

The mass of the solid product is less than the mass of the solid reactant in each of the following, except ............

1. A heating iron(II) oxalate away from air.
2. B heating iron(II) carbonate away from air.
3. C heating iron to redness in air.
4. D reducing iron(III) oxide at a temperature higher than 700°C

When acidified KMnO₄ reacts with FeSO₄ ............

1. A FeSO₄ only is oxidized.
2. B KMnO₄ only is oxidized.
3. C FeSO₄ is oxidized and KMnO₄ is reduced.
4. D no oxidation or reduction takes place.

The iron oxide produced from the thermal decomposition of siderite is characterized by each of the following, except ............

1. A The cation of the oxide is easily oxidized.
2. B It is formed by roasting the compound (FeC₂O₄).
3. C It is formed by passing hydrogen gas over red iron oxide at 650°C
4. D It reacts with dilute acids forming a solution that is easily oxidized.

Each of the following is a property of the compound FeO, except that it ..........

1. A changes colour when exposed to hot air.
2. B dissolves in acids forming iron(II) salts.
3. C is a basic oxide that reacts with dilute acids.
4. D is easily reduced at room temperature.

Iron oxide (X) is produced by reducing the iron oxide that is higher than it in oxidation state with hydrogen at 500°C
Which of the following describes oxide (X)?

1. A Diamagnetic.
2. B It is the main charge in the oxygen converter.
3. C It dissolves in H₂SO₄(aq)
4. D It is affected by carbon monoxide under ordinary conditions.

Iron oxide (X) can be completely oxidized to iron oxide (Y).
Which of the following is correct?

1. A Oxidizing 1 mol of oxide (X) forms 1 mol of oxide (Y).
2. B Oxidizing 2 mol of oxide (X) forms 1 mol of oxide (Y).
3. C Oxide (Y) can be reduced or oxidized.
4. D Oxide (X) can be reduced to the mixed iron oxide.

The following equations show some reactions of metal (R) and its oxide RO:
• 3R(s) + 2O₂(g) ⟶(Δ) R₃O₄(s)
• R(s) + 2HCl(aq) ⟶ RCl₂(aq) + H₂(g)
• RO(s) + 2HCl(aq) ⟶ RCl₂(aq) + H₂O(l)
Element (R) is probably ..........

1. A scandium.
2. B copper.
3. C iron.
4. D zinc.

Which salt has its iron cation oxidized when it is strongly heated away from air?

1. A Iron(II) oxalate.
2. B Iron(II) sulphate.
3. C Iron(II) carbonate.
4. D Iron(III) hydroxide.

Each of the following is a method of preparing a red oxide, except ..........

1. A oxidizing the black iron oxide compound.
2. B the reaction of iron heated to redness with air.
3. C heating iron(II) oxalate in air.
4. D the thermal decomposition of iron(III) hydroxide.

From the following statements:
(1): it is produced by heating FeC₂O₄ in air.
(2): it is produced by reducing Fe₂O₃ with H₂
(3): it reacts with oxygen forming Fe₃O₄
(4): it reacts with dilute acids forming an iron(II) salt.
Which of the previous statements describe iron(II) oxide?

1. A (1) , (2).
2. B (1) , (4).
3. C (2) , (3).
4. D (2) , (4).

Iron(III) oxide is formed by strongly heating salt (X).
What are the hydrated ions formed when salt (X) dissolves in water?

1. A Fe²⁺ , SO₄²⁻
2. B Fe²⁺ , SO₄³⁻
3. C Fe³⁺ , SO₄³⁻
4. D Fe³⁺ , SO₄²⁻

Each of the following produces a black substance, except ..........

1. A heating iron to redness in air.
2. B heating siderite away from air.
3. C passing H₂(g) over haematite at 550°C
4. D strongly heating iron(II) sulphate.

Which of the following is a thermal decomposition reaction and an oxidation-reduction reaction?

1. A Heating iron in atmospheric air.
2. B Heating iron(II) carbonate in the absence of air.
3. C Heating iron(II) sulphate.
4. D Heating iron(III) hydroxide.

What gases or vapours may be formed when iron(II) sulphate is changed into iron?

1. A SO₂ , SO₃ only.
2. B SO₂ , CO₂ only.
3. C SO₂ , SO₃ , H₂O , CO₂
4. D SO₂ , SO₃ , H₂O , CO

Changing iron(III) hydroxide into iron(II) oxide includes the two processes of ............

1. A oxidation then reduction.
2. B thermal decomposition then reduction.
3. C reduction then simple displacement.
4. D thermal decomposition then oxidation.

Metal (M) is part of the chemical composition of the yellow hydrated ore (X).
Each of the following is correct, except ............

1. A Metal (M) reacts with hot concentrated sulphuric acid, but concentrated nitric acid makes it apparently passive.
2. B Metal (M) is used as a catalyst in the industrial preparation of ammonia.
3. C Ore (X) decomposes by heat forming FeO , SO₂ , SO₃
4. D Ore (X) is used to obtain metal (M).

A student recorded the following observations on a chemical reaction:
• No gas was given off.
• A colour change took place.
• No precipitate was formed.
What are the reactants used in this reaction?

1. A Iron(III) chloride , ammonium hydroxide.
2. B Iron(II) oxide , dilute sulphuric acid.
3. C Iron , steam (at 500°C).
4. D Iron , dilute sulphuric acid.

In the following series of reactions:
Which of the following is correct?

1. A (1): a thermal decomposition reaction , (3): dilute hydrochloric acid.
2. B (2): an oxidation reaction , (4): sodium hydroxide.
3. C (1): an oxidation reaction , (4): sodium hydroxide.
4. D (2): a reduction reaction , (3): concentrated sulphuric acid.

From the opposite chart:
Which of the following is correct?

1. A Process (1): oxidation , process (2): reduction , substance (X): NaOH(aq) , process (3): displacement
2. B Process (1): reduction , process (2): oxidation , substance (X): H₂O(l) , process (3): thermal decomposition
3. C Process (1): oxidation , process (2): reduction , substance (X): H₂O(l) , process (3): displacement
4. D Process (1): reduction , process (2): oxidation , substance (X): NaOH(aq) , process (3): thermal decomposition

Which of the following is correct for the iron compound used as a red colour in paints?

1. A The oxidation number of iron in this compound is +2
2. B It is reduced by CO at a temperature higher than 700°C, forming iron.
3. C The mass of iron in it increases when it is roasted.
4. D It can be obtained from the reaction of FeO with dilute H₂SO₄.

Each of the following applies to iron(III) oxide, except that it ............

1. A is paramagnetic.
2. B is the product of roasting siderite.
3. C dissolves in dilute HCl.
4. D is a basic oxide.

The opposite figure shows a rock of the Earth's crust that contains one of the iron ores.
What is the chemical equation that shows one of the reactions of the main chemical compound in this ore?

1. A Fe₃O₄(s) + H₂(g) ⟶(400 : 700°C) 3FeO(s) + H₂O(v)
2. B 4FeO(s) + O₂(g) ⟶(Δ) 2Fe₂O₃(s)
3. C Fe₂O₃(s) + 3H₂SO₄(l , conc) ⟶(Δ) Fe₂(SO₄)₃(aq) + 3H₂O(v)
4. D FeO(s) + 2HCl(aq) ⟶ FeCl₂(aq) + H₂O(l)

What processes are used to change magnetic iron oxide into iron(III) chloride?

1. A Reduction → oxidation → neutralization.
2. B Oxidation → oxidation → neutralization.
3. C Oxidation → neutralization → reduction.
4. D Neutralization → reduction → oxidation.

1 mol of SO₃ gas reacts with 1 mol of iron oxide (X), forming only 1 mol of salt (Y) as the product of the reaction, which decomposes by heat forming iron(III) oxide.
What are the chemical formulas of oxide (X) and salt (Y)?

1. A Oxide (X): Fe₂O₃ , salt (Y): Fe₂(SO₄)₃
2. B Oxide (X): FeO , salt (Y): FeSO₄
3. C Oxide (X): Fe₂O₃ , salt (Y): FeSO₄
4. D Oxide (X): FeO , salt (Y): Fe₂(SO₄)₃

From the opposite chart:
Which of the following is correct?

1. A (1): Fe₂O₃ , (2): FeO , (3): Fe₃O₄
2. B (1): Fe₂O₃ , (2): Fe₃O₄ , (3): FeO
3. C (1): FeO , (2): Fe₂O₃ , (3): Fe₃O₄
4. D (1): FeO , (2): Fe₃O₄ , (3): Fe₂O₃

Changing iron(III) oxide into iron(II) sulphate includes each of the following, except ..........

1. A reducing the compound Fe₂O₃, forming a basic oxide.
2. B the reaction of iron(II) oxide with sulphuric acid, forming a salt and water.
3. C using H₂ gas as a reducing agent.
4. D the products of reducing Fe₂O₃ not differing with the reaction temperature.

Iron(II) sulphate can be changed in practice into an iron(III) chloride solution.
What are the numbers of moles of iron oxide and of the acid used to produce 4 mol of iron(III) chloride solution, respectively?

1. A 2 , 4
2. B 2 , 12
3. C 4 , 6
4. D 2 , 2

From the opposite chart:
Which of the following is correct?

1. A (1): iron(III) hydroxide , (2): iron(II) oxide.
2. B (1): iron(II) hydroxide , (3): iron(II) sulphate.
3. C (1): iron(II) hydroxide , (2): iron(III) oxide.
4. D (2): iron(III) oxide , (3): iron(III) sulphate.

The following chart shows some chemical reactions:
Which of the following is correct?

1. A Both compounds (1) and (3) dissolve in water.
2. B Both compounds (2) and (3) dissolve in water.
3. C Compound (1) decomposes on strong heating, forming iron and steam.
4. D Compound (3) decomposes on strong heating, forming a red powder.

When substance (X) is heated, Fe₂O₃ is formed; when substance (Y) is heated away from air, FeO is formed; and when substance (Z) is heated to 500°C in air, Fe₃O₄ is formed.
Which of the following is correct?

1. A (X): FeSO₄ , (Y): Fe , (Z): FeC₂O₄
2. B (X): Fe , (Y): FeC₂O₄ , (Z): FeSO₄
3. C (X): FeSO₄ , (Y): FeC₂O₄ , (Z): Fe
4. D (X): FeC₂O₄ , (Y): Fe , (Z): FeSO₄

The opposite chart includes three types of iron compounds.
Which of the following gives the types of these compounds?

1. A (X): an iron oxide , (Y): an iron hydroxide , (Z): an iron salt.
2. B (X): an iron salt , (Y): an iron oxide , (Z): an iron hydroxide.
3. C (X): an iron hydroxide , (Y): an iron oxide , (Z): an iron salt.
4. D (X): an iron salt , (Y): an iron hydroxide , (Z): an iron oxide.

From the following chart:
Which of the following is correct?

1. A (1): HCl , (3): Fe(OH)₃
2. B (2): FeCl₃ , (4): Fe(OH)₃
3. C (3): Fe(OH)₂ , (4): NH₄Cl
4. D (1): Cl₂ , (2): FeCl₂

When the salt (FeC₂O₄) is heated in air, the solid compound (X) is produced; when (X) is reduced at 270°C, the solid compound (Y) is produced.
Which of the following is correct?

1. A (X): reacts with HCl(aq) , (Y): reacts with H₂SO₄(aq)
2. B (X): reacts with H₂SO₄(l) , (Y): reacts with H₂SO₄(l)
3. C (X): reacts with HCl(aq) , (Y): reacts with H₂SO₄(l)
4. D (X): reacts with H₂SO₄(l) , (Y): reacts with HCl(aq)

From the chemical formula shown in the opposite figure:
What is element (M), and how can it be obtained from the oxide M₂O₃?

1. A Fe , by oxidation.
2. B Fe , by reduction.
3. C Co , by oxidation.
4. D Co , by reduction.

How many coloured compounds are used and produced in changing iron(III) hydroxide into magnetic iron oxide?

1. A 1
2. B 2
3. C 3
4. D 4

When iron heated to redness reacts with air, a compound is formed that ..........

1. A 1 mol of it is reduced by 4 mol of H₂, forming 1 mol of iron.
2. B 1 mol of it reacts with 8 mol of HCl, forming 2 mol of FeCl₃ and water only.
3. C 1 mol of it is reduced by 1 mol of H₂ (at 600°C).
4. D is oxidized to FeO when heated in air.

Each of the following is correct for one of the iron oxides, except that it ..........

1. A is prepared by oxidizing Fe₃O₄
2. B is prepared by heating iron(II) oxalate in air.
3. C reacts with hot concentrated mineral acids forming iron(III) salts and steam.
4. D is prepared by reducing one of the black iron oxides.

Each of the following describes the properties of red iron oxide, except that it ..........

1. A is prepared by heating iron(II) sulphate in air.
2. B reacts with dilute acids forming solutions of iron(III) salts.
3. C forms a black compound when it is reduced.
4. D can be reduced to two types of oxides.

Which of the following is produced from the reaction of the opposite oxide with hot concentrated acids?

1. A M²⁺ salts only.
2. B M³⁺ salts only.
3. C M⁺ , M²⁺ salts
4. D M²⁺ , M³⁺ salts

When 1 mol of magnetic iron oxide reacts with 8 mol of hot concentrated hydrochloric acid, ............ is formed.

1. A 6 mol of products
2. B 5 mol of chloride ions
3. C 2 mol of iron(III) chloride
4. D 3 mol of iron(III) ions

Magnetic iron oxide can be changed into a salt solution that forms a reddish-brown precipitate with an alkaline solution by ............

1. A reducing magnetic iron oxide, then reacting the product with dilute HCl.
2. B reducing magnetic iron oxide, then reacting the product with water.
3. C oxidizing magnetic iron oxide, then reacting the product with NaOH solution.
4. D oxidizing magnetic iron oxide, then reacting the product with hot concentrated HCl.

The iron oxide prepared by heating iron in air to redness reacts with ..........

1. A hot concentrated hydrochloric acid, forming an iron(II) salt and water.
2. B hot concentrated sulphuric acid, forming an iron(III) salt and water.
3. C hot concentrated hydrochloric acid, forming iron(II) and iron(III) salts and water.
4. D hot concentrated sulphuric acid, forming iron(I) and iron(II) salts and water.

When 1 mol of one of the two black iron oxides is oxidized in air, .......... is formed.

1. A 2 mol of red iron oxide
2. B 0.5 mol of yellow iron oxide
3. C 2 mol of yellow iron oxide
4. D 0.5 mol of red iron oxide

When a sample of the black iron ore compound (X) is heated in air, it changes into the red iron ore compound (Y).
The ratio between the coefficient of the ore compound (X) and the coefficient of the ore compound (Y) in the balanced equation is ..........

1. A (X : 1) : (Y : 2)
2. B (X : 2) : (Y : 5)
3. C (X : 2) : (Y : 3)
4. D (X : 3) : (Y : 4)

Here are four chemical equations:
(1) 4Ca + W ⟶ 4CaO + 3Fe
(2) 3C + 2Fe₂O₃ ⟶ 3CO₂ + X
(3) 4FeS + 7O₂ ⟶ 4SO₂ + 2Y
(4) CO + Z ⟶ CO₂ + Fe
Which of the following is correct?

1. A (W): is reduced to Fe₂O₃ , (X): used as a catalyst , (Y): found in haematite ore , (Z): easily oxidized in hot air
2. B (W): is reduced to Fe₂O₃ , (X): ductile and malleable , (Y): does not dissolve in water , (Z): a compound with magnetic properties
3. C (W): a compound with magnetic properties , (X): the backbone of heavy industries , (Y): a red compound , (Z): a black compound
4. D (W): a compound with magnetic properties , (X): the backbone of heavy industries , (Y): a black compound , (Z): a red compound

The way to obtain magnetic iron oxide from iron(II) oxide is shown by the scheme in ..........

1. A Figure (A)
2. B Figure (B)
3. C Figure (C)
4. D Figure (D)

From the opposite chart:
Which of the following is correct?

1. A (1): Fe₂O₃ , (2): FeO , (3): Fe₃O₄ , (4): Fe₂O₃
2. B (1): Fe₃O₄ , (2): FeO , (3): Fe , (4): Fe₂O₃
3. C (1): Fe₃O₄ , (2): Fe , (3): FeO , (4): Fe₂O₃
4. D (1): Fe₂O₃ , (2): Fe , (3): Fe₃O₄ , (4): FeO

The opposite scheme includes oxidation and reduction reactions of iron and its oxides.
Which of the following is correct?

1. A (1): a black oxide , (2): a black oxide , (3): a red oxide , (4): iron
2. B (1): a black oxide , (2): a red oxide , (3): a black oxide , (4): iron
3. C (1): iron , (2): a black oxide , (3): a red oxide , (4): a black oxide
4. D (1): iron , (2): a red oxide , (3): a black oxide , (4): a black oxide

From the opposite chart:
Which of the following is correct?

1. A (A): Fe₂O₃ , (B): FeSO₄ , (C): FeO
2. B (A): FeO , (B): FeSO₄ , (D): Fe
3. C (B): Fe₂O₃ , (C): Fe , (D): FeSO₄
4. D (B): Fe , (C): Fe₂O₃ , (D): FeO

Iron oxide (X) can be obtained by reducing the other two iron oxides.
Show with symbolic equations how oxide (X) is obtained from:
(1) one of the other two oxides.
(2) a thermal decomposition reaction.

Iron oxide (X) can be obtained by oxidizing the other two iron oxides.
Show with symbolic equations how oxide (X) is obtained from two thermal decomposition reactions.

The following table shows the results of the reactions of three metals of the first transition series with dilute sulphuric acid and with air:
• Metal (M): reaction with dilute sulphuric acid: dissolves slowly forming a solution, with gas bubbles , reaction with air on heating: forms the black oxide (1)
• Manganese: reaction with dilute sulphuric acid: dissolves quickly in the acid forming the stable solution (2), with gas bubbles given off , reaction with air on heating: forms oxide (3), which is a mixture of the (II) and (III) oxides
• Chromium: reaction with dilute sulphuric acid: dissolves quickly in the acid forming a solution , reaction with air on heating: forms oxide (4), which is used in making dyes
Deduce the chemical formula of each of:
(1) oxide (1).
(2) solution (2).
(3) oxide (3).
(4) oxide (4).

Metal (M) is used in making surgical instruments, and the opposite structural formula represents one of its oxides:
(1) Explain why this oxide is described as mixed, using the two oxidation numbers of metal (M) in it.
(2) Show with a symbolic equation the product of:
(a) reducing this oxide.
(b) oxidizing this oxide.

The number of moles of the substance produced from combining 4 mol of iron with excess sulphur equals that produced with excess chlorine.
Express the previous statement with two symbolic equations that show it.

From the opposite chart:
(1) Give two properties of compound (1).
(2) Write the electron configuration of the iron ion in:
(a) compound (2).
(b) compound (3).

2 mol of iron oxide (X) are oxidized forming 1 mol of oxide (Y), while 3 mol of oxide (Y) are reduced forming 2 mol of oxide (Z):
(1) Give the chemical formula of:
(a) oxide (X).
(b) oxide (Z).
(2) Can oxide (Y) be oxidized? Explain.

Metal (X) is soft in the pure state, so carbon is added to it in definite ratios to increase its hardness. One of its oxides is XO.
Write the balanced symbolic equation for the reaction of:
(1) metal (X) with air (at 500°C).
(2) oxide XO with dilute hydrochloric acid.

From the following two statements:
• Statement (1): when a sample of the black iron ore (X) is heated in air, it changes into the red compound (Y).
• Statement (2): the product of reducing compound (Y) differs with the reaction temperature.
(1) What is the ratio between the number of moles of compound (Y) and the number of moles of the ore compound (X) in the balanced equation?
(2) What oxide is produced by reducing compound (Y) at:
(a) the lowest possible temperature?
(b) the highest possible temperature?

The opposite chart includes the three iron oxides:
(1) Give the numbers of the two oxides that have the same chemical formula.
(2) What is the number of the oxide that reacts with hot concentrated sulphuric acid, forming only iron(III) sulphate solution and steam?

The opposite chart shows oxidation and reduction processes of the three iron oxides.
Write the symbolic equation for:
(1) the reduction reaction (X).
(2) the oxidation reaction (Y).

From the opposite chart, write the two symbolic equations that show changing:
(1) the compound FeSO₄ into compound (2).
(2) compound (2) into FeSO₄

Which of the following processes increases the oxidation state of the iron ion in its compounds?
(Sample exam 2026)

1. A Heating the compound produced by adding ammonium hydroxide to iron(III) chloride to above 200°C
2. B Heating the compound produced by adding iron to dilute sulphuric acid.
3. C Strongly heating limonite ore in air.
4. D Heating siderite ore away from air.

Which of the following is needed to prepare iron(III) sulphate from iron(II) sulphate?
(Sample exam 2026)

1. A Thermal decomposition, then adding dilute sulphuric acid.
2. B Thermal decomposition, then adding concentrated sulphuric acid.
3. C Adding sodium hydroxide, then adding dilute sulphuric acid.
4. D Oxidation, then adding sodium hydroxide.

The following chart shows some reactions of iron and its compounds:
From the previous chart, which of the following is correct?
(Sample exam 2026)

1. A Replacing chlorine with dilute hydrochloric acid gives the same product (B).
2. B Both (A) and (D) react with concentrated sulphuric acid giving a mixture of iron(II) and iron(III) sulphates.
3. C Compounds (B) and (C) have the same magnetic moment, and (C) can be reduced to (A) with hydrogen at 500°C
4. D Compound (C) reacts with dilute hydrochloric acid to give compound (B).

Fe₂O₃ can be obtained by all the following methods, except ..........
(Sample exam 2026)

1. A Adding H₂SO₄(dil) to the product of reducing Fe₃O₄ / adding an alkali / heating above 200°C
2. B Passing hot air over iron heated to redness / oxidation.
3. C Leaving iron(II) sulphate in air for some time / adding an alkali / heating above 200°C
4. D Adding iron to dilute oxalic acid / heating in air.

Which of the following gives the correct order of the processes needed to obtain a black iron oxide from FeCl₃?
(Sample exam 2026)

1. A Adding an alkaline solution – thermal decomposition – reduction.
2. B Thermal decomposition – oxidation – adding an alkaline solution.
3. C Adding an alkaline solution – reduction – thermal decomposition.
4. D Thermal decomposition – reduction – adding an alkaline solution.

Which of the following gives the order of the processes carried out on magnetic iron oxide to obtain a reddish-brown precipitate?
(Sample exam 2026)

1. A Reacting with concentrated sulphuric acid, then adding ammonia solution after some time.
2. B Oxidation, then reacting with dilute sulphuric acid, then adding ammonia solution.
3. C Reduction at 430°C, then reacting with dilute hydrochloric acid, then adding ammonia solution.
4. D Reacting with dilute hydrochloric acid, then adding ammonia solution.

(A) and (B) are iron(II) salts; the thermal decomposition of each of them in the absence of air gives one of the iron oxides, as shown by the following equations:
A(s) ⟶(Δ) C(s) + D(g) + E(g)
B(s) ⟶(Δ) G(s) + L(g) + M(g)
Gas (D) is a reducing agent in the extraction of iron.
Which of the following gives (A), (B), (C) and (G)?
(Sample exam 2026)

1. A (A): (COO)₂Fe , (B): FeSO₄ , (C): FeO , (G): Fe₂O₃
2. B (A): Fe(OH)₃ , (B): FeCO₃ , (C): Fe₂O₃ , (G): FeO
3. C (A): (COO)₂Fe , (B): FeSO₄ , (C): Fe₂O₃ , (G): FeO
4. D (A): FeCO₃ , (B): Fe(OH)₃ , (C): FeO , (G): Fe₂O₃

The following chart shows reactions of iron compounds:
Which of the following gives the chemical formulas of (X), (Y) and (Z)?
(Sample exam 2026)

1. A (X): Fe₂O₃ , (Y): Fe , (Z): Fe₃O₄
2. B (X): Fe₃O₄ , (Y): FeO , (Z): Fe₂O₃
3. C (X): Fe₂O₃ , (Y): FeO , (Z): Fe₃O₄
4. D (X): FeO , (Y): Fe , (Z): Fe₂O₃

Which of the following steps are correct for obtaining iron(III) hydroxide from iron(II) oxalate?
(2nd session 2024)

1. A Heating away from air – adding HCl – adding NH₄OH
2. B Heating in air – reduction at 500°C – adding dilute sulphuric acid – adding NH₄OH
3. C Heating in air – reduction at 800°C – adding chlorine – adding NH₄OH
4. D Adding HCl – adding NH₄OH – heating to redness

Iron filings can be used to distinguish between ..........
(Trial exam / June 2021)

1. A concentrated sulphuric acid and concentrated nitric acid.
2. B dilute hydrochloric acid and dilute sulphuric acid.
3. C iron(II) sulphate and iron(III) sulphate.
4. D iron(III) oxide and iron(III) sulphate.

From the opposite chart:
The substances (A), (B), (C) and (D), respectively, are ..........
(2nd session 2022)

1. A (A): H₂O(v) , (B): CO₂(g) , (C): H₂(g) , (D): CO₂(g)
2. B (A): O₂(g) , (B): CO(g) , (C): H₂(g) , (D): H₂O(v)
3. C (A): H₂O(v) , (B): H₂(g) , (C): CO(g) , (D): CO₂(g)
4. D (A): O₂(g) , (B): H₂O(v) , (C): CO(g) , (D): CO₂(g)

From the opposite chart:
Given that (A) and (B) are both iron compounds,
the choice that gives (A) and (B) is ..........
(2nd session 2022)

1. A (A): Fe₂O₃ , (B): FeO
2. B (A): FeSO₄ , (B): Fe₂(SO₄)₃
3. C (A): Fe₃O₄ , (B): FeO
4. D (A): (COO)₂Fe , (B): FeSO₄

When iron(II) oxalate is strongly heated in atmospheric air, a solid compound (X) is formed, and when hot concentrated sulphuric acid is added to compound (X), another compound (Y) is formed. Comparing the properties of compounds (X) and (Y), we find that ..........
(Trial exam / May 2021)

1. A compound (X) is greater than compound (Y) in magnetic moment, and compound (Y) does not dissolve in water.
2. B compound (X) equals compound (Y) in magnetic moment, and compound (X) dissolves in water.
3. C compound (X) equals compound (Y) in magnetic moment, and compound (Y) dissolves in water.
4. D compound (Y) is greater than compound (X) in magnetic moment, and compound (X) does not dissolve in water.

Which of the following processes happen to iron(II) oxalate, in order, to produce iron?
(1st session 2023)

1. A Oxidation – reduction – thermal decomposition.
2. B Thermal decomposition – oxidation – reduction.
3. C Reduction – oxidation – thermal decomposition.
4. D Thermal decomposition – reduction – oxidation.

When dilute sulphuric acid was added to substance (X), a salt solution was formed; after some time, ammonia solution was added to the product and a precipitate was formed.
Which of the following choices is correct «for substance (X) – the salt – the precipitate, respectively»?
(Trial exam / March 2023)

1. A Substance (X): FeO , salt: FeSO₄ , precipitate: Fe(OH)₂
2. B Substance (X): Fe₂O₃ , salt: Fe₂(SO₄)₃ , precipitate: Fe(OH)₃
3. C Substance (X): Fe₃O₄ , salt: Fe₂(SO₄)₃ , precipitate: Fe(OH)₂
4. D Substance (X): FeO , salt: FeSO₄ , precipitate: Fe(OH)₃

Which of the following processes is correct for obtaining red iron oxide?
(Trial exam / March 2023)

1. A Heating iron in air to redness for a short time.
2. B Adding dilute sulphuric acid to iron(II) oxide, then heating the product.
3. C Heating iron(II) carbonate away from atmospheric air.
4. D Passing hot steam over iron heated at 500°C

When the compounds FeO, Fe₃O₄ and FeCO₃ are heated strongly in atmospheric air, each one separately, and the mass of the solid product after heating is compared, ..........
[Fe = 56 , C = 12 , O = 16]
(Trial exam / May 2021)

1. A the mass of Fe₃O₄ is not affected and the mass of FeO increases
2. B the mass of FeCO₃ increases and the mass of Fe₃O₄ is not affected
3. C the mass of FeCO₃ increases and the mass of FeO decreases
4. D the mass of FeCO₃ decreases and the mass of Fe₃O₄ increases

Study the opposite chart. Which of the following gives compounds (1), (2) and (3), respectively?
(Trial exam / May 2021)

1. A (1): FeCl₂ , (2): Fe₂O₃ , (3): Fe(OH)₃
2. B (1): FeCl₃ , (2): Fe(OH)₃ , (3): Fe₂O₃
3. C (1): FeCl₃ , (2): Fe₂O₃ , (3): Fe(OH)₃
4. D (1): FeCl₂ , (2): FeO , (3): Fe(OH)₂

Which of the following steps are correct for obtaining iron(III) hydroxide from iron(II) oxide?
(1st session 2024)

1. A Heating in air – reduction at a temperature above 700°C – adding hot concentrated sulphuric acid – adding ammonium hydroxide solution.
2. B Adding hydrochloric acid – adding ammonium hydroxide solution – heating away from air.
3. C Heating in air – reduction at 400°C – adding dilute sulphuric acid – adding ammonium hydroxide solution.
4. D Strong heating in air – adding hot concentrated sulphuric acid – adding ammonium hydroxide solution.

To obtain magnetic iron oxide from iron(III) chloride, the processes that must be carried out, in order, are ..........
(1st session 2021)

1. A reacting with hydrochloric acid – oxidation – reduction.
2. B reacting with an alkaline solution – thermal decomposition – reduction.
3. C oxidation – reduction – thermal decomposition.
4. D thermal decomposition – oxidation – reacting with an alkaline solution.

When dilute sulphuric acid is added to a test tube containing a mixture of iron(II) oxide and iron(III) oxide, after the reaction is complete the tube will contain ..........
(2nd session 2021)

1. A iron(III) sulphate, iron(III) oxide and hydrogen.
2. B iron(II) oxide, iron(III) oxide and sulphur dioxide.
3. C iron(II) sulphate, iron(III) oxide and water.
4. D iron(III) sulphate, hydrogen and sulphur dioxide.

The following chart shows reactions of iron and its oxides under their suitable conditions:
Which of the following choices gives (A), (B) and (C)?
(1st session 2023)

1. A (A): Fe₃O₄ , (B): FeO , (C): Fe₂O₃
2. B (A): FeO , (B): Fe₃O₄ , (C): Fe₂O₃
3. C (A): FeO , (B): Fe₂O₃ , (C): Fe₃O₄
4. D (A): Fe₂O₃ , (B): Fe₃O₄ , (C): FeO

The following chart shows some reactions under their suitable conditions:
Which of the following choices is correct for compounds (A), (C) and (E)?
(2nd session 2023)

1. A (A): Fe₂O₃ , (C): Fe , (E): FeO
2. B (A): FeO , (C): Fe₂O₃ , (E): Fe
3. C (A): Fe₃O₄ , (C): FeO , (E): Fe
4. D (A): FeO , (C): Fe₃O₄ , (E): Fe₂O₃

The following chart shows iron and its compounds:
(1) Write the chemical formulas of (C) and (D).
(2) Name an intermetallic alloy of substance (B).
(3) Name compound (C) when (X) is replaced with dilute HCl.
(Sample exam 2026)

The following chart shows some processes carried out on some iron compounds:
(1) Write the chemical formulas of (F) and (B).
(2) Give the number of the process that is a thermal decomposition with no change in the magnetic moment of the iron ion.
(3) Name process number (3).
(Sample exam 2026)

Study the following chart, then answer:
(1) Write the chemical formulas of the compounds (X), (Y) and (M).
(2) Write the chemical formula of the compound with the highest magnetic moment in the previous chart.
(Sample exam 2026)

The following chart shows some reactions of iron and its compounds:
(1) Name process number (1) and process number (2).
(2) Write the chemical formula of each of (C) and (D).
(Sample exam 2026)

Study the following chart of iron compounds, then answer:
What are the chemical formulas of the compounds (A), (B), (C) and (D)?
(1st session 2025)