IGCSE Chemistry (0620) — May–June 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 →The diagram shows the result of dropping a purple crystal into water. after water five hours purple solution purple crystal Which processes take place in this experiment? chemical…
Answer this question and get it marked →Which row about elements, mixtures and compounds is correct? metallic non-metallic mixture compound element element A copper methane brass sulfur B brass sulfur copper methane C…
Answer this question and get it marked →The atomic structures of four particles, W, X, Y and Z, are shown. electrons neutrons protons W 2 2 2 X 2 2 3 Y 2 3 2 Z 3 2 3 Which particles are isotopes of the same element? A W…
Answer this question and get it marked →Which statement explains why isotopes of the same element have the same chemical properties? A They have the same number of outer shell electrons. B They have the same number of…
Answer this question and get it marked →Nitrogen forms a nitride ion with the formula N3–. Which particle does not have the same electronic configuration as the nitride ion? A Al 3+ B Cl – C Na+ D O2–
Answer this question and get it marked →Which row describes the formation of single covalent bonds in methane? A atoms share a pair of electrons both atoms gain a noble gas electronic structure B atoms share a pair of…
Answer this question and get it marked →Which formula is an empirical formula? A C2H4O B C4H8O2 C C3H7COOH D CH3CH2CH2COOH
Answer this question and get it marked →Heating iron sulfide, FeS2, in air produces sulfur dioxide. 4FeS2 + 11O2 → 2Fe2O3 + 8SO2 What is the maximum mass of sulfur dioxide produced from 120 kg of iron sulfide? A 64 kg B…
Answer this question and get it marked →Which substance produces hydrogen and bromine when electrolysed? A concentrated aqueous copper(II) bromide B concentrated aqueous sodium bromide C dilute aqueous potassium bromide…
Answer this question and get it marked →Which statements about hydrogen fuel cells are correct? 1 Water is formed as the only waste product. 2 Both water and carbon dioxide are formed as waste products. 3 The overall…
Answer this question and get it marked →Ethene gas, C2H4, is completely burned in excess oxygen to form carbon dioxide and water. The equation for this exothermic reaction is shown. C2H4 + 3O2 → 2CO2 + 2H2O The table…
Answer this question and get it marked →Which row describes the effect on the activation energy and the frequency of particle collisions when the temperature of a chemical reaction is increased? activation frequency…
Answer this question and get it marked →Solid copper(II) sulfate exists in two different forms, anhydrous and hydrated. One of these forms is blue and the other is white. The change between these two forms is…
Answer this question and get it marked →Sodium ions, Na+, and oxygen ions, O2–, combine with chromium ions to form a salt. The salt sodium dichromate has the formula Na2Cr2O7. What is the oxidation state of chromium in…
Answer this question and get it marked →The concentration of hydrogen ions in 100 cm3 of 0.1 mol / dm3 hydrochloric acid is higher than the concentration of hydrogen ions in 100 cm3 of 0.1 mol / dm3 ethanoic acid. Which…
Answer this question and get it marked →Which oxide is classified as an amphoteric oxide? A aluminium oxide B calcium oxide C copper(II) oxide D nitrogen oxide
Answer this question and get it marked →Which method produces the salt copper(II) carbonate? A Add copper(II) oxide to water, then add excess aqueous sodium carbonate. Filter off the precipitate. B Add copper(II) oxide…
Answer this question and get it marked →Which statements about the trends across a period of the Periodic Table are correct? 1 Aluminium is more metallic than sodium. 2 Beryllium is more metallic than carbon. 3 Boron is…
Answer this question and get it marked →Some information about elements in Group II of the Periodic Table is shown. time taken to make 10 cm3 density in melting element of hydrogen gas when 1 g of g / cm3 point / °C…
Answer this question and get it marked →A new element oxfordium, Ox, was discovered with the following properties. electrical formula bonding in a solubility conduction of element molecule of Ox2 insoluble in water does…
Answer this question and get it marked →Which row describes a similarity and a difference between chlorine and bromine? similarity difference A both are gases at room chlorine and bromine temperature and pressure have…
Answer this question and get it marked →Which statement describes transition elements? A They have high densities and high melting points. B They have high densities and low melting points. C They have low densities and…
Answer this question and get it marked →Which gas is made when powdered zinc is added to dilute hydrochloric acid? A carbon dioxide B chlorine C hydrogen D oxygen
Answer this question and get it marked →The diagram represents the structure of a solid. Which solids does the diagram represent? brass graphite sodium chloride A ✓ ✓ ✗ B ✓ ✗ ✗ C ✗ ✓ ✓ D ✗ ✗ ✓
Answer this question and get it marked →Steel is an alloy of iron. Which statement explains why steel is stronger than iron? A Steel contains carbon which is a very hard substance. B The carbon atoms in steel bond…
Answer this question and get it marked →Three students, X, Y and Z, are told that solid P reacts with dilute acids and also conducts electricity. The table shows the students’ suggestions about the identity of P. X Y Z…
Answer this question and get it marked →Which statement explains why aluminium appears to be unreactive? A It is coated in an oxide layer. B It has a low density. C It is low in the reactivity series. D It is solid at…
Answer this question and get it marked →During the electrolysis of aluminium oxide, the mass of the carbon anode changes. Which row describes the change and gives a reason for this change? mass change reason of the…
Answer this question and get it marked →Several processes are used to treat domestic water. Which row identifies a reason for the given process? process reason A chlorination removes impurities B filtration removes…
Answer this question and get it marked →What is the equation for photosynthesis? A CO2 + 3H2 → CH3OH + H2O B 6CO2 + 6H2O → C6H12O6 + 6O2 C C6H12O6 → 2C2H5OH + 2CO2 D C6H12O6 + 6O2 → 6CO2 + 6H2O
Answer this question and get it marked →Which statement describes how the C–H bonds in methane gas in the atmosphere contribute to global warming? A They absorb thermal energy from the Sun and emit some of this energy…
Answer this question and get it marked →The structural formulae of two hydrocarbons are shown. CH3CH2CH2CH3 CH3CH(CH3)CH3 Which statement about the hydrocarbons is correct? A They are both alkenes. B They decolourise…
Answer this question and get it marked →The structural formula of compound Q is given. CH3CH2CH2COOCH2CH2CH3 What is compound Q? A butyl butanoate B butyl propanoate C propyl butanoate D propyl propanoate
Answer this question and get it marked →The fractional distillation of petroleum is shown. Which fraction contains hydrocarbons with the longest chain length? fuel gas A B C D petroleum bitumen
Answer this question and get it marked →Which equation represents the cracking of an alkane? A 3C2H4 → C6H12 B C6H12 + H2 → C6H14 C C6H14 → 6C + 7H2 D C6H14 → C2H4 + C4H10
Answer this question and get it marked →What is the structure of the product of the reaction of propene with bromine? A B C D H H H H Br H H Br H H H H H C C C Br H C C C H C C C Br Br C C C Br H H H H Br H H H H H H
Answer this question and get it marked →In reaction R, 2000 molecules of CH2=CH2 react to form a single molecule X only. 2000 CH2=CH2 → X Which terms describe reaction R, CH2=CH2 and X? reaction R CH2=CH2 X A addition…
Answer this question and get it marked →Part of the structure of a polymer is shown. H O H O N C N C N C H O Which statements about the polymer are correct? 1 The polymer is nylon. 2 The polymer is formed by…
Answer this question and get it marked →The concentration of acids and alkalis can be determined by titration. Which pieces of equipment are needed to perform a titration? 1 2 3 4 A 1 and 2 B 1 and 3 C 2 and 3 D 2 and 4
Answer this question and get it marked →Which chromatogram shows how the Rf value of a substance is calculated? A B C D x y x x x y y y y y x x Rf = x Rf = x Rf = y Rf = y
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