IGCSE 2020 4CH1/1C January (pdf)
- This question is about gases in the atmosphere.
(a) The box gives the names of some gases in the atmosphere.
Choose gases from the box to answer these questions.
Each gas may be used once, more than once or not at all.
(i) Identify a noble gas
(ii) Identify a gas that makes up about 78% of the atmosphere.
(iii) Identify a greenhouse gas.
(iv) Identify a gas produced by the thermal decomposition of calcium carbonate
(b) Sulfur reacts with oxygen to produce sulfur dioxide gas.
(i) Write a chemical equation for this reaction.
(ii) State an environmental problem caused when sulfur dioxide gas dissolves in
water in the atmosphere.
- The diagram shows the electronic configuration of an atom of an element
(a) Complete the table by giving the missing information about this atom.
(b) This element has three isotopes.
The table shows the mass number and percentage abundance of each isotope in a
sample of this element.
Calculate the relative atomic mass (Ar) of this element.
Give your answer to one decimal place.
- The diagram shows two samples of iron, A and B.
Sample B is coated with a thin layer of zinc.
(a) Name the process used to coat iron with zinc
(b) The two samples of iron are left outside for several weeks.
A brown solid containing hydrated iron(III) oxide forms on sample A.
(i) Give the common name for the brown solid
(ii) Give the names of the two substances that react with the iron to form the brown solid
(c) Iron can be formed by reacting aluminium powder with iron(III) oxide.
The diagram shows how this reaction can be demonstrated
When the magnesium fuse is lit, a very exothermic reaction occurs.
(i) State the meaning of the term exothermic.
(ii) The equation for the reaction between aluminium and iron(III) oxide is
2Al + Fe2O3 → 2Fe + Al2O3
Explain what this reaction shows about the relative reactivities of aluminium and iron
(iii) Explain why the reaction between aluminium and iron(III) oxide is a redox reaction.
- This question is about ionic compounds.
(a) The table shows the formulae of some positive and negative ions, and the formulae
of some compounds containing these ions
(i) Complete the table by giving the three missing formulae.
(ii) Give the name of the compound with the formula NH4NO3
(b) Sodium oxide, Na2O, is an ionic compound.
The sodium and oxide ions are held together by ionic bonds.
(i) State the meaning of the term ionic bond.
(ii) The diagram shows the arrangement of the electrons in a sodium atom and in
an oxygen atom.
Draw diagrams in the boxes to show the arrangement of the electrons in the
ions of sodium oxide.
Include the charges on the ions
- The boxes show the displayed formulae of six organic compounds, P, Q, R, S, T and U
(a) Use the letters P, Q, R, S, T and U to answer these questions.
Each letter may be used once, more than once or not at all.
(i) Give the letter of the compound that is not a hydrocarbon.
(ii) Give the letters of the two compounds that have the same empirical formula.
(iii) Give the letter of the compound that is used to manufacture poly(propene)
(b) Describe a test that can be used to distinguish between compounds Q and T
(c) Compounds P, Q and R are members of the same homologous series.
Give two characteristics of a homologous series
(d) This is the displayed formula of an alkene, V.
(i) Give the name of alkene V.
(ii) Draw the displayed formula of another alkene that is an isomer of alkene V.
(e) An organic compound has the percentage composition by mass
C = 36.36% H = 6.06% F = 57.58%
(i) Show that the empirical formula of the compound is CH2F
(ii) The relative molecular mass (Mr) of the compound is 66.
Determine the molecular formula of the compound
- A student uses this method to investigate the reaction of dilute hydrochloric acid with zinc.
- pour some dilute hydrochloric acid into a glass beaker
- record the initial temperature of the acid
- add a piece of zinc and stir the mixture
- record the temperature of the mixture after one minute
(a) Write a word equation for the reaction of dilute hydrochloric acid with zinc
(b) The diagram shows the thermometer readings for this reaction.
Complete the table, giving all values to the nearest 0.1°C.
(c) Another student repeats the method using five different metals to compare their reactivity.
(i) This student uses a polystyrene cup instead of a glass beaker.
Explain why a polystyrene cup is better than a glass beaker in this investigation.
(ii) Give three factors that the student should keep constant in this investigation
(d) The table shows some of the student’s results.
(i) State why there is no temperature change for copper
(ii) Predict the temperature change for iron.
(iii) Deduce the order of reactivity of the five metals.
- This question is about some of the halogens and their compounds.
(a) (i) Which element is a liquid at room temperature?
(ii) Which element has the palest colour?
(iii) Which element is the least reactive?
(b) A teacher uses displacement reactions to demonstrate the reactivities of some halogens.
She adds solutions of chlorine, bromine and iodine separately to three different
sodium halide solutions.
The table shows some of the teacher’s results
A change in colour of the solution indicates that a reaction has occurred.
(i) Complete the table by predicting the missing results.
(ii) State why the teacher does not add bromine solution to sodium bromide solution.
(iii) The word equation for the reaction of bromine with sodium iodide is
bromine + sodium iodide → iodine + sodium bromide
Write a chemical equation for this reaction.
(c) A technician sees an unlabelled bottle containing a liquid.
He knows that the liquid is a solution of one of these compounds.
- copper(II) chloride
- copper(II) bromide
- iron(II) chloride
- iron(II) bromide
Describe chemical tests that the technician could use to identify the compound in
- (a) Carbon dioxide changes directly from a solid to a gas without becoming a liquid.
(i) Give the name of the change of state from solid to gas
(ii) Describe the test for carbon dioxide gas
(b) Carbon dioxide is a simple molecular covalent substance.
Explain why carbon dioxide turns from a solid to a gas at a very low temperature.
(c) Diamond and graphite are both giant covalent substances made up of carbon atoms.
- diamonds are used in cutting tools
- graphite is used in pencils to make marks on paper
Explain, with reference to structure and bonding, why each substance is suitable
for its particular use.
- This is the student’s method.
- measure the mass of the spirit burner and fuel
- add 100cm3 of water to the copper can
- record the temperature of the water
- use the spirit burner to heat the water until the temperature rises by 30°C
- immediately measure the new mass of the spirit burner and fuel
(a) Suggest why the student measures the mass of the spirit burner and fuel immediately
after heating the water.
(b) When the fuel is burned, the student notices that a black solid forms on the bottom
of the copper can.
(i) Identify the black solid.
(ii) Explain why the black solid forms.
(c) (i) Show that the heat energy change, Q, to raise the temperature of 100cm3 of
water by 30°C is approximately 13kJ.
[mass of 1.0cm3 of water = 1.0g]
[c for water = 4.2 J/g/°C]
(ii) The student burns 0.96g of methanol, CH3OH
Calculate the molar enthalpy change, ΔH, in kJ/mol, for the combustion of methanol.
Include a sign in your answer.
[Mr of methanol = 32]
(d) The table shows data book values for the molar enthalpy change, ΔH, for the
combustion of some alcohols with different numbers of carbon atoms per
(i) Plot the data values from the table on the grid.
Draw a straight line of best fit
(ii) Deduce the value of ΔH for an alcohol with six carbon atoms per molecule.
Show on the graph how you obtained your answer.
(iii) State the relationship between ΔH and the number of carbon atoms per molecule
- Nitric acid (HNO3) is used in the production of fertilisers.
Nitric acid is manufactured in three stages.
Stage 1 ammonia reacts with oxygen in the presence of a platinum catalyst to
produce nitrogen monoxide gas, NO, and water.
Stage 2 nitrogen monoxide gas reacts with more oxygen to produce
nitrogen dioxide gas, NO2.
Stage 3 nitrogen dioxide gas reacts with water to produce nitric acid and more
nitrogen monoxide gas.
(a) (i) Complete the chemical equation for the reaction in stage 1.
(ii) Give the meaning of the symbol
(iii) State the purpose of the platinum catalyst
(b) Give a chemical equation for the reaction of nitrogen monoxide and oxygen in stage 2
(c) (i) The equation for the reaction in stage 3 is
3NO2 + H2O → 2HNO3 + NO
Calculate the maximum mass, in tonnes, of nitric acid that could be produced
in this reaction from 11.5 tonnes of nitrogen dioxide
(ii) Suggest what use can be made of the nitrogen monoxide gas formed in stage 3.
(d) When copper(II) oxide reacts with dilute nitric acid, copper(II) nitrate is produced.
The equation for the reaction is
0.200 mol of nitric acid reacts with excess copper(II) oxide.
A mass of 15.3g of copper(II) nitrate is produced.
Calculate the percentage yield of copper(II) nitrate.
[Mr of copper(II) nitrate = 187.5]
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