IGCSE Chemistry Past Paper Topic Questions

1.1.1 Properties of Solids Liquids and Gases Paper 4 IGCSE Chemistry Topic Questions

Q1: (a) Use ideas about the movement and arrangement of particles to explain why:

Solids have a definite volume and shape
Liquids have a definite volume but no definite shape
Gases have no definite volume or shape

.................................................................................................................................................... [4]

....................................................................................................................................................

Mark scheme: (a) Any four from: [4]

Solids: particles close together / no space between particles / particles arranged regularly / particles touching
Solids: particles only vibrate
Allow: particles cannot move / particles in fixed positions
Liquids: particles can slide over each other / particles have limited movement
Ignore: particles can move unqualified
Liquids: particles close together / particles not arranged regularly / particles arranged randomly / particles not in fixed positions
Ignore: particles further apart than in solids
Gases: particles far apart / particles arranged randomly
Gases: particles can move everywhere / particles move anywhere / particles move randomly
Note: It must be clear which state is being referred to
Note: There must be reference to particles (or atoms / molecules / ions) in the answer to gain marks

1.1.2 Structure of Solids Liquids and Gases Paper 4 IGCSE Chemistry Topic Questions

Question Paper:

(a) Complete the table, using ticks (✔) and crosses (✘), to describe the properties of gases, liquids and solids.

state of matter	particles are touching	particles have random movement	particles are regularly arranged
gas
liquid
solid

Mark Scheme:
1 mark for each correct row.

State touching random movement regularly arranged

Gas ✔

Liquid ✔ ✔

Solid ✔ ✔

State	touching	random movement	regularly arranged
Gas		✔
Liquid	✔	✔
Solid	✔		✔

1.1.3 State Changes Paper 4 IGCSE Chemistry Topic Questions

Q1:
Substances can change state.
- (i) Boiling and evaporation are two ways in which a liquid changes into a gas.
  Describe two differences between boiling and evaporation.
  1. ..........................................................................................................................................
  2. ....................................................................................................................................[2]..
- (ii) Name the change of state when:
  - A gas becomes a liquid: ................................................................................................
  - A solid becomes a gas: ..........................................................................................[2]......
Mark Scheme:
- (i):
  - Boiling happens at a specific temperature (1)
  - Boiling has bubbles (1)
- (ii):
  - A gas becomes a liquid: condensation (1)
  - A solid becomes a gas: sublimation (1)

1.1.4 Effect of Temperature and Pressure on Gases Paper 4 IGCSE Chemistry Topic Questions

Q1:
Substances can change state.
- (i) Boiling and evaporation are two ways in which a liquid changes into a gas.
  Describe two differences between boiling and evaporation.
  1. ..........................................................................................................................................
  2. ..........................................................................................................................................
  [2]
- (ii) Name the change of state when:
  - A gas becomes a liquid: ................................................................................................
  - A solid becomes a gas: ................................................................................................
  [2]
Mark Scheme:
- (i):
  - Boiling happens at a specific temperature (1)
  - Boiling has bubbles (1)
- (ii):
  - A gas becomes a liquid: condensation (1)
  - A solid becomes a gas: sublimation (1)

1.1.2 Diffusion Paper 4 IGCSE Chemistry Topic Questions

Q1: The elements shown are gases at room temperature and pressure:
- Hydrogen
- Nitrogen
- Oxygen
- Chlorine
When separate samples of each of these gases are placed in a container, they will diffuse.
- (i) Describe why these gases diffuse.
  ....................................................................................................................................... [1]
- (ii) State which of these four gases has the highest rate of diffusion. Explain your answer.
  - Gas: ......................................................................................................................................
  - Explanation: ......................................................................................................................... ............................................................................................................................................. [2]

Mark Scheme:
- (i) random motion of molecules / particles. [1]
- (ii) Hydrogen:
  - lowest (relative) molecular mass. [2]

Q2: The rate of diffusion of a gas was studied.

The following data shows the relative molecular masses (Mr) and rates of diffusion of the gases:

Gas	Temperature	rate of diffusion in cm3 / min
Nitrogen	25	1.00
Chlorine	25	0.63
Nitrogen	50	1.05

(i) Explain why nitrogen gas diffuses faster than chlorine gas.
....................................................................................................................................... [2]
(ii) Explain why the nitrogen gas diffuses faster at the higher temperature.
....................................................................................................................................... [1]

Mark Scheme:
- (i)
  - nitrogen has smaller Mr; [1]
  - nitrogen (molecules) move faster (than chlorine molecules) / ora. [1]
  - note: comparison must be made.
- (ii)
  - (at higher temperature) molecules move faster / have more energy. [1]

2.1.2 Atomic Structure Basics Paper 4 IGCSE Chemistry Topic Questions

Q1: Atoms and ions are made from small particles called electrons, neutrons, and protons.

(a) Complete the table:

Particle	Relative Charge	Relative Mass
Electron	-1	1/1840
Neutron	_	_
Proton	_	_

(b) Complete the table for atoms and ions A, B, and C:

Atom or Ion	Number of Electrons	Number of Neutrons	Number of Protons	Symbol
A	18	_	20	⁴²₂₀Ca²⁺
B	_	18	_	³⁵₁₇Cl^1-
C	18	16	16

Mark Scheme:

(a):

Particle	Relative Charge	Relative Mass
Electron	-1	1/1840
Neutron	0	1
Proton	+1	1

(b):

Atom or Ion	Details
A	20 neutrons, Symbol: ⁴²₂₀Ca²⁺ [1]
B	17 protons, 18 neutrons, Symbol: ³⁵₁₇Cl [1]
C	16 protons, 16 neutrons, Symbol: S^2– [1]

2.1.2 Periodic Table Basics Paper 4 IGCSE Chemistry Topic Questions

Q: Define market disequilibrium. [2]
Mark Scheme:
- A market where demand and supply are not equal / balanced / matched (2).
- A market where there is a surplus / excess supply (1) or a shortage / excess demand (1).

2.3 Isotopes Basics Paper 4 IGCSE Chemistry Topic Questions

Q1 (a): Sulfur exists as a number of different isotopes. What is meant by the term isotopes?

Atoms with the same number of protons or atoms of the same element or atoms with the same atomic number [1]
Atoms with a different number of neutrons or atoms with a different mass number or atoms with a different nucleon number [1]

2.3 Isotopes Percentage Abundance Paper 4 IGCSE Chemistry Topic Questions

Question 1:
Table 2.2 shows the relative abundance of the two naturally occurring isotopes of copper.

Table 2.2

Isotope ⁶³Cu ⁶⁵Cu

Relative abundance 70% 30%

Calculate the relative atomic mass of copper to one decimal place.

Relative atomic mass = ................................................................. [2]
Mark Scheme:
- M1: (63 × 70) + (65 × 30) = 6360 (1)
- M2: 6360 / 100 = 63.6 (1)
[2]

Isotope	⁶³Cu	⁶⁵Cu
Relative abundance	70%	30%

2.4 Ions and Ionic Bonds Paper 4 IGCSE Chemistry Topic Questions

Q: Identify two determinants of price elasticity of demand. [2]
Mark Scheme:
- Availability of substitutes (1)
- Availability of complements (1)
- Proportion of income (1)
- Whether the product is a luxury or a necessity / essential (1)
- Whether it is addictive (1)
- Whether the purchase can be postponed (1)
- Impact of advertising / brand loyalty (1)

2.4.1 Ionic Compounds Physical Properties Paper 4 IGCSE Chemistry Topic Questions

Question Paper 1:
Give three physical properties of ionic compounds.
1. ..........................................................................................................................................
2. ..........................................................................................................................................
3. ..........................................................................................................................................
[3]
Mark Scheme:
- High melting point or boiling point
- Hard
- Brittle
- Soluble in water / insoluble in organic solvents
- Conduct electricity in liquid state or in aqueous solution
- Non-conductors or poor conductors (when solid)
[3]

2.5 Simple Molecules and covalent Compounds Dot Cross Diagrams Paper 4 IGCSE Chemistry Topic Questions

Question: Complete the dot-and-cross diagram to show the arrangement of electrons in a molecule of ester Y.
Diagram:

Mark Scheme:

M1: Two crosses on the inner circle circumference labeled 'O' (up and down).
M2: Two dots on the inner circle circumference labeled 'C' (up and down).
M3: Correct arrangement of all other circles.

2.7 Metallic Bonding Paper 4 IGCSE Chemistry Topic Questions

Q1: Describe the metallic bonding in zinc and then explain why it is a good conductor of electricity. [4]

Mark Scheme:

Positive ions / cations [1] (Not nuclei / atoms)
Delocalised / free / mobile or sea of electrons [1]
Bond is attraction between (positive) ions and delocalised electrons [1]
It is a good conductor because there are delocalised / free / mobile electrons [1] (Note: must indicate electrons are moving / carry charge)

2.6.1 Macromolecule Diamond / Graphite/ Silicon Dioxide Paper 4 IGCSE Chemistry Topic Questions

Question Paper 1:
Diamond and graphite are different solid forms of carbon. The carbon atoms in diamond and graphite are arranged in different ways.
- (a) State the number of covalent bonds each carbon atom has in diamond. [1]
- (b) State the term used to describe the structure of diamond. [1]
- (c) Name an oxide that has a similar structure to diamond. [1]
- (d) Describe the arrangement of atoms in graphite. [2]
- (e) Explain how graphite conducts electricity. [1]
Mark Scheme:
- (a): 4 (1)
- (b): Giant covalent (1)
- (c): Silicon dioxide (1)
- (d):
  - M1: Layers
  - M2: Hexagonal (rings of carbon) [2]
- (e): Mobile electrons (1)

2.7 Metallic Bonding Paper 4 IGCSE Chemistry Topic Questions

Q1: Describe the metallic bonding in zinc and then explain why it is a good conductor of electricity. [4]

Mark Scheme:

Positive ions / cations [1] (Not nuclei / atoms)
Delocalised / free / mobile or sea of electrons [1]
Bond is attraction between (positive) ions and delocalised electrons [1]
It is a good conductor because there are delocalised / free / mobile electrons [1] (Note: must indicate electrons are moving / carry charge)

3.1 / Molecular Formular and Empirical Formula Paper 4 IGCSE Chemistry Topic Questions

Q1: Magnesium phosphate contains magnesium ions, Mg²⁺, and phosphate ions, PO₄^3–. Deduce the formula of magnesium phosphate. [1]

Mark Scheme:

Mg₃(PO₄)₂ [1]

Q2: Sulfur dioxide reacts with aqueous sodium sulfite to produce a compound with the following composition by mass: 29.1% Na, 40.5% S and 30.4% O. Calculate the empirical formula of this compound. Empirical formula = .............................. [3]

Mark Scheme:

29.1 / 23, 40.5 / 32, 30.4 / 16 or 1.2(65), 1.2(65), 1.9 [1]

1:1:1.5 [1]

Empirical formula: Na₂S₂O₃ [1]

Q3:

(a) Compound X has the following composition by mass:

H, 3.66%; P, 37.80%; O, 58.54%

Calculate the empirical formula of compound X.

empirical formula = .............................. [2]

(b) Compound Y has the empirical formula H₃PO₄ and a relative molecular mass of 98.

Deduce the molecular formula of compound Y.

molecular formula = .............................. [1]

Mark Scheme:

(a)

M1: H = 3.66 / 1, P = 37.80 / 31, O = 58.54 / 16
OR H = 3.66, P = 1.22, O = 3.66
OR H:P:O = 3:1:3 [1]

M2: H₃PO₃ [1]

(b): H₃PO₄ [1]

3.1.2 /Formula of Ions and Compounds Paper 4 IGCSE Chemistry Topic Questions

Q1: Magnesium phosphate contains magnesium ions, Mg²⁺, and phosphate ions, PO₄^3–. Deduce the formula of magnesium phosphate. [1]

Mark Scheme:

Mg₃(PO₄)₂ [1]

3.2 Word Equations and Symbol Equations Paper 4 IGCSE Chemistry Topic Questions

Q1: Element X is a Group III metal. It burns in air to form an oxide X₂O₃.
Write a symbol equation for this reaction.
.............................................................................................................................................. [2]

Mark Scheme:

Formulae [1]
Balance, 4X + 3O₂ → 2X₂O₃ [1]

Q2: Complete the word equation for this reaction.

Sodium bromide + Chlorine → .............................. + ..............................

Mark Scheme:

calcium oxide (1)
carbon dioxide (1)

3.3 Calculating Moles/ Concentration Paper 4 IGCSE Chemistry Topic Questions

Question: The equation for the reaction is shown:

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

Calculate the concentration of NaOH(aq) formed, in g/dm³, when 0.345 g of sodium is added to 50.0 cm³ of distilled water. Assume there is no change in volume.

Use the following steps:

● Calculate the number of moles of Na added.
= .............................. mol
● Determine the number of moles of NaOH formed.
= .............................. mol
● Calculate the concentration of NaOH in mol/dm³.
concentration of NaOH = .............................. mol/dm³
● Determine the Mr of NaOH and calculate the concentration of NaOH in g/dm³.
concentration of NaOH = .............................. g/dm³

Mark Scheme:

M1: mol Na = 0.345 / 23 = 0.015(00) (1)
M2: mol NaOH = M1 = 0.015(00) (1)
M3: M2 × 1000 / 50 = 0.015(00) × 20 = 0.3(00) (1)
M4: Mr NaOH = 40 (1)
M5: M4 × M3 = 40 × 0.3 = 12.(0) (g/dm³) (1)

3.3 Molar Gas Volume Paper 4 IGCSE Chemistry Topic Questions

Question: Calculate the volume of oxygen, measured at r.t.p., which is formed when 1.60 g of CuO reacts as shown in the equation:

4CuO → 2Cu₂O + O₂

Answer: .................................................... dm³ [3]

Mark Scheme:

M1: mol CuO = (1.60 ÷ 80) = 0.02(00) mol [1]
M2: mol O₂ = (M1 ÷ 4 = 0.02 ÷ 4) = 0.005(00) mol [1]
M3: vol O₂ = M2 × 24.0 = 0.005 × 24.0 = 0.12(0) dm³ [1]

3.4 Excess / Limiting Reactants Paper 4 IGCSE Chemistry Topic Questions

Question: Propanol reacts with methanoic acid to form the ester propyl methanoate.

CH₃CH₂CH₂OH + HCOOH → HCOOCH₂CH₂CH₃ + H₂O

4.0 g of methanoic acid was reacted with 6.0 g of propanol.

(i) Calculate the Mr of methanoic acid = ........................................ [1]
(ii) Calculate the Mr of propanol = ........................................ [1]
(iii) Determine which one is the limiting reagent. Show your reasoning.

.............................................................................................................................................
.............................................................................................................................................
............................................................................................................................................. [2]

Mark Scheme:

M1: moles of CH₃CH₂CH₂OH = 0.1 [1]
M2: moles of HCOOH = 0.087 (0.09) and limiting reagent is methanoic acid [1]

3.5 Percentage Yield / Percent by Mass Paper 4 IGCSE Chemistry Topic Questions

Question:

(i) 5.95 g of cobalt(II) carbonate were added to 40 cm³ of hydrochloric acid, concentration 2.0 mol / dm³.
Calculate the maximum yield of cobalt(II) chloride-6-water and show that the cobalt(II) carbonate was in excess.

CoCO₃ + 2HCl → CoCl₂ + CO₂ + H₂O
CoCl₂ + 6H₂O → CoCl₂.6H₂O

maximum yield:
number of moles of HCl used = ........................................
number of moles of CoCl₂ formed = ........................................
number of moles of CoCl₂.6H₂O formed = ........................................
mass of one mole of CoCl₂.6H₂O = 238 g
maximum yield of CoCl₂.6H₂O = ........................................ g

Mark Scheme:

number of moles of HCl used = 0.04 × 2 = 0.08 [1]
number of moles CoCl₂ formed = 0.04 [1]
number of moles CoCl₂.6H₂O formed = 0.04 [1]
maximum yield of CoCl₂.6H₂O = 9.52 g [1]
Allow: 9.5
Allow: ecf on number of moles of HCl

4.1 Electrolysis Basics Paper 4 IGCSE Chemistry Topic Questions

Electrode Question

Q1:
- a State two reasons why carbon (graphite) is suitable to use as an electrode.[2]
- Current Flow Question
  b Name the particle responsible for the conduction of electricity in the metal wires used in a circuit.[1]

Mark Scheme:
- a
  - M1 inert (1)
  - M2 good conductor of electricity (1)
  [2]
- b electron [1]

4.1.3 Electrolysis of Molten Compounds Paper 4 IGCSE Chemistry Topic Questions

Q1: Molten potassium bromide can be electrolysed. Predict the products of this electrolysis at:
the anode ..................................................................................................................................
the cathode .............................................................................................................................. [2].
Mark Scheme:
the anode: bromine / Br₂ ................................................................................................................. 1
the cathode: potassium / K ...................................................................................................................... [1].

4.1.4.1 Electrolysis of Aqueous Compounds [ Concentrated] Paper 4 IGCSE Chemistry Topic Questions

Question 1: This question is about electrolysis.

Concentrated hydrochloric acid is electrolysed using the apparatus shown.[ DIgram has not been included here. KIndly refer to tghe paper 0620_w21_qp_41-q3]
(a) Chloride ions are discharged at the anode.
- (i) Complete the ionic half-equation for this reaction.
  .......... Cl^–(aq) → ..........(g) + .......... e^– [2]
- (ii) State whether oxidation or reduction takes place. Explain your answer.
  ..................................................................................................................
  .................................................................................................................. [1]
(b) Describe what is seen at the cathode.
..................................................................................................................
.................................................................................................................. [1]
(c) Write the ionic half-equation for the reaction at the cathode.
..................................................................................................................
.................................................................................................................. [2]
(d) The pH of the electrolyte is measured throughout the experiment.
- (i) Suggest the pH of the electrolyte at the beginning of the experiment.
  .................................................................................................................. [1]
- (ii) State how the pH changes, if at all, during the experiment.
  Explain your answer.
  ..................................................................................................................
  ..................................................................................................................
  .................................................................................................................. [2]

Mark Scheme:

3(a)(i):
- 2Cl ^– → Cl ₂ + 2e^– (1)
- Rest of the equation (1)
- Total: 2
3(a)(ii):
- Oxidation AND lose electrons (1)
- Total: 1
3(b):
- Effervescence (of colourless gas) (1)
- Total: 1
3(c):
- 2H⁺ + 2e^– → H₂
- H⁺ + e^– as the only species on LHS (1)
- Rest of the equation fully correct (1)
- Total: 2
3(d)(i):
- (1)
- Total: 1
3(d)(ii):
- M1: Increase (1)
- M2: H⁺ ions being removed (1)
- Total: 2

4.1.4.2 Electrolysis of Aqueous Compounds [ Dilute] Paper 4 IGCSE Chemistry Topic Questions

Q1: A student carries out an electrolysis experiment using the apparatus shown.
- [Diagram not included here. But it has two carbon electrodes and dilute aqueous sodium chloride as the electrolyte. Diagram can be found at: 0620/42/M/J/21-q4]
- The student uses dilute aqueous sodium chloride.
  - (a) State the name given to any solution which undergoes electrolysis.
    .............................................................................................................................................. [1]
  - (b) Hydroxide ions are discharged at the anode.
    - (i) Complete the ionic half-equation for this reaction.
      ..........OH–(aq) → ........................... + O2 (g) + 4e– [2]
    - (ii) Explain how the ionic half-equation shows the hydroxide ions are being oxidised.
      ....................................................................................................................................... [1]
  - (c) Describe what the student observes at the cathode.
    .............................................................................................................................................. [1]
  - (d) Write the ionic half-equation for the reaction at the cathode.
    .............................................................................................................................................. [2]

Mark Scheme:
- (a) electrolyte [1]
- (b)(i) 4OH⁻ → 2H₂O + O₂ + 4e⁻
  - balance of charge (1)
  - rest of equation (1)
  [2]
- (b)(ii) (OH⁻(aq) ions) lose electrons [1]
- (c) fizzing [1]
- (d) 2H⁺ + 2e⁻ → H₂
  - species correct (1)
  - fully correct equation (1)
  [2]

4.1.5 Electrolysis of Brine Paper 4 IGCSE Chemistry Topic Questions

Q1: Brine is concentrated aqueous sodium chloride.
(i) Name three substances which are manufactured by passing electricity through brine.
1 ..........................................................................................................................................
2 ..........................................................................................................................................
3 .......................................................................................................................................... [3]
Mark Scheme:
(i) hydrogen
chlorine
sodium hydroxide ................................................................................................................. 3
4(e)(ii) sodium ...................................................................................................................... 1

4.1.6 Electrolysis of Dilute Sulfuric Acid Paper 4 IGCSE Chemistry Topic Questions

Q1:
(a) Dilute sulfuric acid is electrolysed using the apparatus shown in the diagram.
(i) State what is meant by the term electrolysis.
.............................................................................................................................................
.............................................................................................................................................
....................................................................................................................................... [2]
(ii) Explain why inert electrodes are used.
.............................................................................................................................................
....................................................................................................................................... [1]
(iii) Name the products formed at each electrode.
negative electrode ..............................................................................................................
positive electrode ................................................................................................................ [2]
(iv) Write an ionic half‑equation for the reaction at the negative electrode.
....................................................................................................................................... [2]
Mark Scheme:
(a)(i) breakdown by (the passage of) electricity (1)
of an ionic compound in molten/aqueous (state) (1) ................................................................................. 2
(a)(ii) they do not react ...................................................................................................................... 1
(a)(iii) negative electrode: hydrogen (gas) (1)
positive electrode: oxygen (gas) (1)
(a)(iv) H⁺ + e^- as the only species on the left (1)
equation fully correct (1) ...................................................................................................................... 2
2H⁺ + 2e^- → H₂ (scores 2)

4.1.7 Electrolysis of Copper Sulfate Paper 4 IGCSE Chemistry Topic Questions

Qp1:
Copper has the structure of a typical metal. It has a lattice of positive ions and a “sea” of mobile electrons. The lattice can accommodate ions of a different metal.
(a) Aqueous copper(II) sulphate solution can be electrolysed using carbon electrodes. The ions present in the solution are as follows.
Cu²⁺(aq), SO₄^2-(aq), H⁺(aq), OH^-(aq)
(i) Write an ionic equation for the reaction at the negative electrode (cathode).
(ii) A colourless gas was given off at the positive electrode (anode) and the solution changes from blue to colourless.
Explain these observations.
(b) Aqueous copper(II) sulphate can be electrolysed using copper electrodes. The reaction at the negative electrode is the same but the positive electrode becomes smaller and the solution remains blue.
(i) Write a word equation for the reaction at the positive electrode.
(ii) Explain why the colour of the solution does not change.
(iii) What is the large scale use of this electrolysis?
Mark Scheme:
(a) (i) Cu²⁺ + 2e^- = Cu [1]
(ii) gas is oxygen [1]
(copper(II) sulphate) changes to sulphuric acid
or copper ions removed from solution [1]
(b) (i) copper atoms - electrons = copper ions
accept correct symbol equation [1]
(ii) concentration of copper ions does not change or
amount or number of copper ions does not change [1]
copper ions are removed and then replaced
or copper is transferred from anode to cathode [1]
(iii) refining copper or plating (core)
or extraction of boulder copper [1]

4.1.7 Electrolysis -Mixed Bag [ Mutiple Concepts Tested in One Question] Paper 4 IGCSE Chemistry Topic Questions

Question Paper:

The results of experiments on electrolysis using inert electrodes are given in the table.
Complete the table; the first line has been completed as an example.

electrolyte	change at negative electrode	change at positive electrode	change to electrolyte
molten lead(II) bromide	lead formed	bromine formed	used up
.......................................	potassium formed	iodine formed	used up
dilute aqueous sodium chloride	.......................................	.......................................	.......................................
aqueous copper(II) sulfate	.......................................	.......................................	.......................................
.......................................	hydrogen formed	bromine formed	potassium hydroxide formed

Mark Scheme:
- molten potassium iodide NOT aqueous [1]
- hydrogen [1]
- oxygen [1]
- water used up or solution becomes more concentrated or sodium chloride remains
- NOT no change
- If products are given as hydrogen, chlorine and sodium hydroxide then 2/3
- copper [1]
- oxygen (and water) [1]
- sulfuric acid accept hydrogen sulfate [1]
- aqueous or dilute or concentrated potassium bromide [1]
- accept correct formulae

4.1.8 Construct Ionic Half Equations Paper 4 IGCSE Chemistry Topic Questions

Q1: Electrolysis is carried out on aluminium oxide dissolved in molten cryolite.
Write the ionic half-equation for the reaction occurring at the negative electrode. [2]
Mark Scheme:
(ii) Al³⁺ + 3e^- → Al
M1 only Al³⁺ + (3) e^- on the left [1]
M2 equation fully correct [1]

4.1.9 Electroplating Paper 4 IGCSE Chemistry Topic Questions

Q1:

One of the methods used to prevent iron or steel from rusting is to electroplate it with another metal, such as tin. Complete the following.
The anode is made of ................................................. .
The cathode is made of ................................................. .
The electrolyte is a solution of ............................................[3] .

Marking Scheme:

anode

tin NOT impure tin [1]

cathode

iron or steel [1]

electrolyte

tin salt or tin ions as electrolyte

NOT oxide or hydroxide or carbonate [1]

Q1:
- A metal spoon is electroplated with copper.
- State what is used as:
  - the positive electrode (anode) ......................................................................................
  - the negative electrode (cathode) ...................................................................................
  - the electrolyte ...................................................................................................................
- [3]

Mark Scheme:
- Positive electrode (anode): copper (1)
- Negative electrode (cathode): spoon (1)
- Electrolyte: (aqueous or solution) of named copper salt (1)

4.2 Hydrogen-Oxygen Fuel Cells Paper 4 IGCSE Chemistry Topic Questions

Q1: Hydrogen–oxygen fuel cells can be used to produce electricity in vehicles.

(i) Write the symbol equation for the overall reaction in a hydrogen–oxygen fuel cell.
.............................................................................................................................................. [2]
(ii) State one advantage of using hydrogen–oxygen fuel cells instead of petrol in vehicle engines.
.............................................................................................................................................. [1]

Mark Scheme:

(i) 2H₂ + O₂ → 2H₂O

M1 all formulae [1]
M2 equation correct [1]

(ii) no carbon dioxide evolved; OR more efficient [1]

5.1.1 Endothermic / Exothermic Reactions Basics Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

5.1.3 Enthalpy Change and Bond Energy Calculation Paper 4 IGCSE Chemistry Topic Questions

Q1: Chloroethene (CH₂=CHCl) can be manufactured from 1,2-dichloroethane (CH₂ClCH₂Cl).
The equation can be represented as shown:

    Cl      H
     |      |
H — C — C — H   →   H — C = C — H   +   H — Cl
     |      |               |
    H      Cl              Cl

Some bond energies are given:
- C—C: 350 kJ/mol
- C=C: 610 kJ/mol
- C—Cl: 340 kJ/mol
- C—H: 410 kJ/mol
- H—Cl: 430 kJ/mol
Use the bond energies in the table to calculate the energy change, in kJ/mol, of the reaction.
Use the following steps:
- Calculate the energy needed to break bonds.
- Calculate the energy released when bonds form.
- Calculate the energy change of the reaction.

Mark Scheme:
M1: 2670 (1)
M2: 2610 (1)
M3: (+) 60 (1)

6.1 Physical and Chemical Change Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.2 effect of changing the concentration of solutions on the rate of reaction Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.2 effect on the rate of reaction of changing the pressure of gases Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.2 effect on the rate of reaction of changing the surface area of solids Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.2 effect on the rate of reaction of changing the temperature Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.2 effect on the rate of reaction of adding or removing a catalyst, including enzymes Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.2 Investigating Rate of Reaction Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.3.1 Reversible Reactions Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.3.2 Effect of Temperature on Equilibrium in a Reversible Reaction Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.3.2 Effect of Pressure on Equilibrium in a Reversible Reaction Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.3.2 Effect of Concentration on Equilibrium in a Reversible Reaction Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.3.2 Effect of Catalyst on Equilibrium in a Reversible Reaction Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.3.2 Effect of water and heat on the Reversible Reaction of Copper Sulfate and Cobalt Chloride Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.3.2 Haber's Process Paper 4 IGCSE Chemistry Topic Questions

Q1: Nitrogen reacts with hydrogen to form ammonia, NH₃, in the Haber process.
- State the essential conditions in the Haber process.
- Write an equation for the chemical reaction.
- ....................................................................................................................................................
  ....................................................................................................................................................
  ....................................................................................................................................................
  ....................................................................................................................................................
  ....................................................................................................................................................
- [4]
Mark Scheme:
- 450 °C (1)
- 200 atmospheres (1)
- Iron (catalyst) (1)
- N₂ + 3H₂ ⇌ 2NH₃ (1)

6.3.2 Contact Process Paper 4 IGCSE Chemistry Topic Questions

Q1: Sulfuric acid is manufactured by an industrial process. Sulfur is obtained from sulfur-containing metal ores.
The sulfur in the metal ore is converted to sulfur dioxide which is then oxidised to sulfur trioxide as shown.
2SO₂(g) + O₂(g) → 2SO₃(g)
- (a) Name a metal ore which contains sulfur.
  .............................................................................................................................................. [1]
- (b) Describe the process which converts metal ores to sulfur dioxide.
  .............................................................................................................................................. [1]
- (c) Name the industrial process used to manufacture sulfuric acid.
  .............................................................................................................................................. [1]
- (d) The reaction that produces sulfur trioxide is an equilibrium. The forward reaction is exothermic.
  - (i) State the temperature and pressure used to make sulfur trioxide.
    temperature = .............................. °C
    pressure = .............................. atm [2]
  - (ii) Name the catalyst used.
    ....................................................................................................................................... [1]
  - (iii) Describe two features of an equilibrium.
    1 ..........................................................................................................................................
    2 .......................................................................................................................................... [2]
  - (iv) State the effect, if any, on the position of equilibrium when the following changes are made. Explain your answers.
    - temperature is increased
      ....................................................................................................
      .............................................................................................................................................
    - pressure is increased
      .......................................................................................................
      ............................................................................................................................................. [4]
- Explain, in terms of particles, what happens to the rate of reaction when the temperature is increased.
  .............................................................................................................................................
  .............................................................................................................................................
  .............................................................................................................................................
  .............................................................................................................................................
  ....................................................................................................................................... [3]

Mark Scheme:
- (a) zinc blende [1]
- (b) strong heating in air / roasting in air [1]
- (c) contact [1]
- (d)(i)
  - M1 450 °C (1)
  - M2 1–2 atm (1)
  [2]
- (d)(ii) vanadium(V) oxide [1]
- (d)(iii)
  - M1 the rate of forward reaction equals (the rate of the) reverse reaction (1)
  - M2 concentrations of reactants and products are constant (1)
  [2]
- (d)(iv)
  - Increased temperature:
    - M1 (position of) equilibrium moves to left-hand side (1)
    - M2 reaction is exothermic (1)
  - Increased pressure:
    - M3 (position of) equilibrium moves to right-hand side (1)
    - M4 more (gaseous) moles/molecules on left-hand side (1)
  [4]

6.3.2 Redox Reaction Paper 4 IGCSE Chemistry Topic Questions

Q1: Iron is extracted from its ore, hematite, in the blast furnace.
Describe the reactions involved in this extraction. Include one equation for a redox reaction and one for an acid/base reaction.
[5]

Mark Scheme:
- One redox equation from: [1]
  - Fe₂O₃ + 3CO → 2Fe + 3CO₂
  - 2Fe₂O₃ + 3C → 4Fe + 3CO₂
  - Fe₂O₃ + 3C → 2Fe + 3CO
  - C + O₂ → CO₂
  - CO₂ + C → 2CO
- One acid/base equation: [1]
  - CaO + SiO₂ → CaSiO₃
  - CaCO₃ + SiO₂ → CaSiO₃ + CO₂
- Any three additional equations or comments from: [3]
  - carbon burns or reacts to form carbon dioxide;
  - this reaction is exothermic or produces heat;
  - carbon dioxide is reduced to carbon monoxide;
  - carbon monoxide reduces hematite to iron;
  - carbon reduces hematite to iron;
  - limestone removes silica to form slag;
  - limestone decomposes;

6.3.2 Oxidation Reduction Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

6.3.2 Oxidising and Reducing Agent Paper 4 IGCSE Chemistry Topic Questions

Q1: The reactivity series shows the metals in order of reactivity.
- (a) The reactivity series can be established using displacement reactions.
  - A piece of zinc is added to aqueous lead nitrate. The zinc becomes coated with a black deposit of lead.
  - Zn + Pb²⁺ → Zn²⁺ + Pb
  - Zinc is more reactive than lead.
- The reactivity series can be written as a list of ionic equations:
  - ...... → ...... + ...... (most reactive metal: the best reductant)
  - Zn → Zn²⁺ + 2e
  - Fe → Fe²⁺ + 2e
  - Pb → Pb²⁺ + 2e
  - Cu → Cu²⁺ + 2e
  - Ag → Ag⁺ + e^–
- (i) Explain why the positive ions are likely to be oxidants (oxidising agents).
  - ..............................................................................................................................
  - [1]
- (ii) Deduce which ion is the best oxidant (oxidising agent).
  - ..............................................................................................................................
  - [1]
- (iii) Which ion(s) in the list can oxidise lead metal?
  - ..............................................................................................................................
  - [1]
Mark Scheme:
- (i) Because they can accept or gain electrons / change into atoms or can be reduced [1]
- (ii) Ag⁺ or silver [1] (charge not essential but if given, it must be correct)
- (iii) Ag⁺ and Cu²⁺ or silver and copper [1]

7.1.1 Effect of Indicators [ litmus, thymolphthalein and methyl orange on Acids Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

7.1.1 REaction of Acids with metals, base, carbonates and ammonium salts Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

7.1.1 Effect of Indicators [ litmus, thymolphthalein and methyl orange on Alkalis Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

7.1.1 Reaction of Base with Acid and Ammonium Salts Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

7.1.1 Strong and Weak Acids Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

7.1.1 Comparing hydrogen ion concentration, neutrality, relative acidity and relative alkalinity in terms of colour and pH using universal indicator paper Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

7.1.1 Neutralisation Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

7.1.1 Acidic Basic and Amphoteric Oxides Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

7.1.1 Neutralisation Reactions Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

7.1.1 Water of Crystallisation Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

8.1 Periodic Table Basics Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

8.2 Group 1 Elements Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

8.3.1 Group 7 Elements Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

8.3.2 Group 7 Reactions Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

8.4 Transition Elements Paper 4 IGCSE Chemistry Topic Questions

Co has high melting point / boiling point ORA for Li
Co has high density ORA for Li
Co has catalytic activity ORA for Li
Co forms coloured compounds ORA for Li
Co compounds have variable oxidation states / form ions with different charges ORA for Li
Co is hard / Co is strong ORA for Li
Co less reactive ORA for Li / Li reacts rapidly with water / Co does not react with water / Co reacts slowly with water
Co is magnetic ORA for Li

8.5 Noble Gases Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

9.1 Properties of Metals Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

9.2.1 Uses of Metals [ Copper and Aluminium] Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

9.3 Alloys Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

9.4 Reactivity Series Paper 4 IGCSE Chemistry Topic Questions

Q1: The reactivity series shows the metals in order of reactivity.
- (a) The reactivity series can be established using displacement reactions.
  - A piece of zinc is added to aqueous lead nitrate. The zinc becomes coated with a black deposit of lead.
  - Zn + Pb²⁺ → Zn²⁺ + Pb
  - Zinc is more reactive than lead.
- The reactivity series can be written as a list of ionic equations:
  - Zn → Zn²⁺ + 2e
  - Fe → Fe²⁺ + 2e
  - Pb → Pb²⁺ + 2e
  - Cu → Cu²⁺ + 2e
  - Ag → Ag⁺ + e
- (i) In the space at the top of the list, write an ionic equation for a metal which is more reactive than zinc.
  - [1]
- (ii) Write an ionic equation for the reaction between aqueous silver(I) nitrate and zinc.
  - ..............................................................................................................................
  - [2]
Mark Scheme:
- (a)
  - (i) Any metal above zinc
  - Mg → Mg²⁺ + 2e^– [1]
  - (ii) Zn + 2Ag⁺ → Zn²⁺ + 2Ag [2]

9.5.1 Corrosion of Iron Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

9.5.2 Barrier Methods and Sacrificial Coating Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

9.6.1 Metal Extraction Basics Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

9.6.1 Iron Extraction Paper 4 IGCSE Chemistry Topic Questions

Q1: The diagram shows a blast furnace used in the extraction of iron.

[The diagram could not be included here]

(a)
- (i) Complete the chemical equation for the reduction of iron(III) oxide in the blast furnace.
  - Fe₂O₃ + 3C → ......Fe + ......CO
  - [2]
- (ii) Explain how this equation shows that iron(III) oxide is reduced.
  - .......................................................................................................................................
  - [1]
(b) One of the products of this reaction reacts with impurities in the iron to form slag.
- Use the information in the diagram to suggest how you know that molten slag is less dense than molten iron.
  - .......................................................................................................................................
  - [1]

Mark Scheme:

(a):
- (i)
  - 2 (Fe) [1]
  - 3 (CO) [1]
- (ii) Iron oxide loses oxygen / it loses oxygen [1]
(b):
- Slag floats above the iron [1]

9.6.1 Aluminium Extraction Paper 4 IGCSE Chemistry Topic Questions

Q1: Aluminium is extracted from its ore by electrolysis.

(a) Name the ore of aluminium which consists mainly of aluminium oxide.
- ..............................................................................................................................................
- [1]
(b) State what is meant by the term electrolysis.
- ....................................................................................................................................................
- ..............................................................................................................................................
- [2]
(c) Electrolysis is carried out on aluminium oxide dissolved in molten cryolite.
- (i) Give two reasons why the electrolysis is carried out on aluminium oxide dissolved in molten cryolite instead of electrolysing molten aluminium oxide only.
  - 1. ..........................................................................................................................................
  - 2. ..........................................................................................................................................
  - [2]
- (ii) Write the ionic half-equation for the reaction occurring at the negative electrode.
  - .......................................................................................................................................
  - [2]
- (iii) The positive electrodes are made of carbon. Explain why the positive carbon electrodes are replaced regularly.
  - .............................................................................................................................................
  - .......................................................................................................................................
  - [2]

Mark Scheme:

(a): Bauxite [1]
(b):
- M1: Breakdown by (the passage of) electricity [1]
- M2: Of an ionic compound in molten or aqueous (state) [1]
(c):
- (i)
  - M1: Improves conductivity of the electrolyte / makes the electrolyte a better conductor [1]
  - M2: Lowers operating temperature [1]
- (ii)
  - M1: Al³⁺ + 3e^– → Al
  - M1: Only Al³⁺ + (3) e^– on the left [1]
  - M2: Equation fully correct [1]
- (iii)
  - M1: Anodes or carbon react(s) with oxygen [1]
  - M2: Form carbon dioxide [1]

10.1.1 Chemical Tests for Water Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

10.1.2 Treatment of Water Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

10.2 Fertilisers Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

10.3.1 Composition of Air Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

10.3.2 Air Pollutants-Sources and Effects Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

10.3.3 Environmental Issues Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

10.3.4 Photosynthesis Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

11.1.1 Homologous Series Paper 4 IGCSE Chemistry Topic Questions

Q1: Compounds in the same homologous series have the same general formula.

(i) Give two other characteristics of members of a homologous series.
.............................................................................................................................................. [2]

Mark Scheme:

Any two from: [2]

(contain the) same functional group
differ from one member to the next by a –CH₂– unit
trend in physical properties
similar chemical properties

11.1.2 Displayed and Structural Formulae Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

11.1.3 Structural Isomers Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

11.1.4 Saturated and Unsaturated Compounds [ Hydrocarbons] Paper 4 IGCSE Chemistry Topic Questions

Q1: Describe a test for an unsaturated hydrocarbon.

test .............................................................................................................................................
observations .............................................................................................................................. [2]

Mark Scheme:

aqueous bromine [1]
decolourises / goes colourless [1]

11.3.1 Fractional Distillation of Petroleum Paper 4 IGCSE Chemistry Topic Questions

Q1: Petroleum is a mixture of hydrocarbons, which can be separated into fractions.

● the name of the process used to separate the fractions
....................................................................................................................................................
● how this process separates the different fractions.
....................................................................................................................................................
....................................................................................................................................................
....................................................................................................................................................
....................................................................................................................................................
.................................................................................................................................................... [4]

Mark Scheme:

(fractional) distillation [1]
petroleum vaporised / heated / turned into a gas [1]
temperature gradient in column / column hotter at bottom / colder at top [1]
smaller hydrocarbons go further up the column / larger hydrocarbons stay near the bottom of the column [1]
different boiling points of fractions / alkanes / molecules / hydrocarbons [1]
fractions / molecules / hydrocarbons come off at different heights in the column [1]

11.3.2 Uses of Petroleum Fractions Paper 4 IGCSE Chemistry Topic Questions

Q1: Complete the table to show the name and uses of some petroleum fractions.

name of fraction	use of fraction
naphtha	making chemicals
kerosene	jet fuel
fuel oil	fuel for ships / fuel for (home) heating

[3]

Mark Scheme:

naphtha: making chemicals [1]
kerosene: jet fuel [1]
fuel oil: fuel for ships / fuel for (home) heating [1]

11.3.2 Alkane Reactions Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

11.5.1 Alkene Reactions Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

11.6.1 Alcohols Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

11.7.1 Carboxylic Acids Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

11.8.1 Polymers Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

11.8.2 Plastics Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

11.8.3 Proteins Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

12.1-Experimental Design Basics Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

12.2-Titrations Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

12.3.1 Chromatography Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

12.4.1-Separation Techniques Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

12.5.1 -Test for Gases Paper 4 IGCSE Chemistry Topic Questions

Q1: Describe the test for sulfur dioxide. test: ______ and observations: ______ [2]

Test: (Aqueous) potassium manganate (VII) [1]
Observation: (Purple to) colourless [1]

12.5.2 -Identifying Ions Paper 4 IGCSE Chemistry Topic Questions

Q: Define market failure. [2]
Mark Scheme:
- Market failure is when the market mechanism / price mechanism / demand and supply (1).
- Does not lead to an efficient allocation of resources (1).

12.5.3 -Flame Tests Paper 4 IGCSE Chemistry Topic Questions

Q1: Describe how to do a flame test on a sample of a salt. [2]

Mark Scheme:

(Compound/salt) on wooden splint or (nichrome/platinum) wire [1]
Into (roaring) Bunsen flame [1]

Q2: The names of the elements of Period 2 of the Periodic Table are shown.
lithium beryllium boron carbon nitrogen oxygen fluorine neon
Answer the following questions about these elements. Each element may be used once, more than once or not at all.
Identify the element which:
produces a red flame in a flame test.

Mark Scheme:

Lithium [1]

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Paper 4 Structured Theory	Extended Syllabus - Sample Copies	0610_s19_qp_42-IGCSE-Biology-Solved-Past-Paper-Questions-And-Answers.pdf Download
Paper 6 Alternative to Practical	Extended Syllabus - Sample Copies	0610_s19_qp_62-IGCSE-Biology-Solved-Past-Paper-Questions-And-Answers.pdf Download

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