IGCSE Chemistry (0620) — October–November 2023, Paper 21
40 questions · every question answerable online with instant point-by-point AI marking against the official mark scheme.
Start with Question 1 →A gas is placed in a sealed container. The gas has a pressure of one atmosphere and a temperature of 50 °C. It is heated to 100 °C. Which row describes the cause of the pressure…
Answer this question and get it marked →Four experiments, each containing a different acidic gas, are set up as shown. The dividing glass plates are removed at the same time. In which set of apparatus does the litmus…
Answer this question and get it marked →The Group I element potassium forms an ionic bond with the Group VII element fluorine. Which two ions are produced? A K+ and F+ B K+ and F– C K– and F– D K– and F+
Answer this question and get it marked →X and Y are atoms. ● X and Y have the same number of electron shells. ● X and Y have the same number of outer electrons. ● X and Y have different mass numbers. Which statements…
Answer this question and get it marked →Lithium chloride is an ionic compound and silicon(IV) oxide is a covalent compound. Which statement about both compounds is correct? A They are not soluble in water. B They…
Answer this question and get it marked →Which equations are balanced? 1 Fe2O3 + 3CO → 2Fe + 3CO2 2 ZnCO3 + 2HCl → ZnCl 2 + CO2 + 2H2O 3 Mg(NO3)2 + NaOH → Mg(OH)2 + 2NaNO3 4 CaCO3 + H2SO4 → CaSO4 + H2O + CO2 A 1 and 2 B…
Answer this question and get it marked →Which row shows the formulae of sodium carbonate, zinc nitrate and ammonium sulfate? sodium carbonate zinc nitrate ammonium sulfate A Na2CO3 ZnNO3 (NH4)2SO4 B Na2CO3 Zn(NO3)2…
Answer this question and get it marked →Which statements about hydrogen and oxygen are correct? hydrogen and oxygen hydrogen and oxygen can can react to produce be made by the electrolysis of electrical energy dilute…
Answer this question and get it marked →Graphite has a giant covalent structure. Which statements about graphite are correct? 1 Carbon atoms form four covalent bonds with neighbouring atoms. 2 There are delocalised…
Answer this question and get it marked →Which reaction pathway diagram represents an endothermic reaction? A B products products energy energy 'H = –24 kJ / mol 'H = +24 kJ / mol reactants reactants progress of reaction…
Answer this question and get it marked →Hydrogen burns in oxygen. The equation for the reaction is shown. 2H2 + O2 → 2H2O The table shows the bond energies involved. bond energy bond in kJ / mol H–H 436 O=O 498 O–H 464…
Answer this question and get it marked →Which process involves a chemical change? A adding sodium to water B boiling water C dissolving sodium chloride in water D producing water from aqueous sodium chloride
Answer this question and get it marked →An experiment is carried out to find the rate of reaction between hydrochloric acid and zinc. Zn(s) + 2HCl (aq) → ZnCl 2(aq) + H2(g) The results of the experiment are shown.…
Answer this question and get it marked →Hydrogen peroxide, H2O2, decomposes to form water and oxygen. 2H2O2(aq) → 2H2O(l) + O2(g) Manganese(IV) oxide catalyses the decomposition reaction. The reaction is investigated in…
Answer this question and get it marked →Sulfuric acid is produced by the Contact process. Which row shows the typical conditions used in the process? pressure temperature catalyst / kPa / °C A iron 200 300 B iron 20 000…
Answer this question and get it marked →Which equation shows the reduction of copper? A CuO + C → Cu + CO B 2CuS + 3O2 → 2CuO + 2SO2 C Cu(g) → Cu(l) D Cu(l) → Cu(s)
Answer this question and get it marked →Which statement about acids is correct? A A weak acid partially dissociates in aqueous solution. B An acid accepts protons when added to water. C Ethanoic acid acts as a strong…
Answer this question and get it marked →Copper(II) sulfate is formed by reacting excess solid copper(II) carbonate with dilute sulfuric acid. Which processes are part of the preparation of solid copper(II) sulfate? 1…
Answer this question and get it marked →Which type of reaction is represented by the equation shown? Pb2+(aq) + 2NO3–(aq) + 2Na+(aq) + 2I–(aq) → PbI2(s) + 2Na+(aq) + 2NO3–(aq) A addition B redox C neutralisation D…
Answer this question and get it marked →Which compound is likely to be coloured? A KMnO4 B KNO3 C K2CO3 D K2SO4
Answer this question and get it marked →Which statements about the metal zinc are correct? 1 It is extracted from the ore bauxite. 2 It is used to galvanise steel. 3 It is used to make the alloy brass. 4 It reacts with…
Answer this question and get it marked →The electronic configurations of four elements, P, Q, R and S, are shown. electronic element configuration P 2 Q 2,2 R 2,6 S 2,8 Which elements are unreactive monatomic gases? A P…
Answer this question and get it marked →Which row compares the strength of alloys with pure metals and explains the difference in strength? strength of an alloy explanation compared to a pure metal A weaker larger atoms…
Answer this question and get it marked →Zinc oxide reacts with carbon to produce zinc. Which equation represents this reaction? A 2ZnO + C → 2Zn + CO B 2ZnO + 2C → 2Zn + 2CO2 C ZnO + C → Zn + CO D ZnO + 2C → Zn + 2CO2
Answer this question and get it marked →When a piece of aluminium foil is added to dilute hydrochloric acid, no effervescence is seen. Which statement explains why no effervescence is seen? A Aluminium does not make a…
Answer this question and get it marked →Iron nails are stored in an airtight container. lid air iron nails The nails begin to rust after a few days. How can the rusting of the nails be prevented? A Leave the lid off. B…
Answer this question and get it marked →Four substances present in the blast furnace during iron extraction are listed. 1 calcium carbonate 2 carbon dioxide 3 carbon monoxide 4 iron(III) oxide Which substances are both…
Answer this question and get it marked →Aluminium is extracted from purified bauxite by electrolysis. Which row shows the ionic half-equations for the reaction at each electrode? anode cathode A Al → Al 3+ + 3e– 2O2– +…
Answer this question and get it marked →Which test is used to show that a sample of water is pure? A Evaporate the water to see if any solids remain. B Heat the water to check its boiling point. C Test with anhydrous…
Answer this question and get it marked →Catalytic converters in car exhausts change polluting gases into non-polluting gases. Which statements about oxides of nitrogen and car engines are correct? 1 The nitrogen in…
Answer this question and get it marked →The structures of two molecules, X and Y, are shown. X Y H H H C H H H H H H H H H H H C C C C C C H H C C C C C C H H H H H H H H H H Which row describes X and Y? structural…
Answer this question and get it marked →What is the structure of butanoic acid? A B H H H H H H H H C C C O H H C C C C O H H H H H H H H C D H H O H H H O H C C C O H H C C C C O H H H H H H
Answer this question and get it marked →When a mixture of methane and chlorine is exposed to ultraviolet light, a reaction takes place. Which statements about this reaction are correct? 1 It is an addition reaction. 2…
Answer this question and get it marked →Esters are formed when a carboxylic acid reacts with an alcohol. What is the catalyst for this reaction? A aqueous potassium manganate(VII) B iron C sulfuric acid D vanadium(V)…
Answer this question and get it marked →The diagram shows part of a polymer. H H H H H H H H C C C C C C C C H H H H H H H H Which diagram shows the monomer from which this polymer is made? A B C D H H H H H H H H C H H…
Answer this question and get it marked →Nylon and PET are polymers. Which statements about these polymers are correct? 1 They are both condensation polymers. 2 HOCH2CH2CH2OH could be a monomer for both polymers. 3 The…
Answer this question and get it marked →Ethane is used as a fuel. Which equation shows the complete combustion of ethane? A 2C2H6 + 7O2 → 4CO2 + 6H2O B 2C2H6 + 5O2 → 4CO + 6H2O C C2H4 + 3O2 → 2CO2 + 2H2O D C2H4 + 2O2 →…
Answer this question and get it marked →The painkiller paracetamol is synthesised from 4-aminophenol. Chromatography is done on an impure sample of paracetamol. The results are shown. The diagram is not drawn to scale.…
Answer this question and get it marked →The equation for the reaction of aqueous calcium nitrate and aqueous sodium hydroxide is shown. Ca(NO3)2(aq) + 2NaOH(aq) → Ca(OH)2(s) + 2NaNO3(aq) Which process is used to remove…
Answer this question and get it marked →The results of two tests on aqueous compound X are given. test: warm with aluminium foil and aqueous sodium hydroxide result: ammonia is produced test: aqueous sodium hydroxide…
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