IGCSE Chemistry (0620) — May–June 2025, Paper 23
40 questions · every question answerable online with instant point-by-point AI marking against the official mark scheme.
Start with Question 1 →Which two changes, when applied at the same time to a fixed amount of gas, cause the greatest increase in volume of the gas? The options give a change in pressure and a change in…
Answer this question and get it marked →Solid G is heated until it melts. It is then left to cool to room temperature. The graph shows the cooling curve for G. The curve shows temperature falling, then a horizontal…
Answer this question and get it marked →Which atom has twice as many neutrons as protons? A proton number 1, nucleon number 1 (1/1 H) B proton number 1, nucleon number 2 (2/1 H) C proton number 1, nucleon number 3 (3/1…
Answer this question and get it marked →What is the nucleon number of an atom? A the number of electrons, neutrons and protons in the nucleus B the number of neutrons and protons in the nucleus C the number of neutrons…
Answer this question and get it marked →The diagram shows the positions of elements P and Q in the Periodic Table. P is in Group II (second period of that group), and Q is in Group VI near the right-hand side of the…
Answer this question and get it marked →Which statement about ionic compounds is correct? A Giant lattices are formed when ionic compounds crystallise from solution. B In all ionic compounds, the metal ions have fewer…
Answer this question and get it marked →The equation for the reaction between iron(III) chloride and sodium hydroxide is shown. FeCl3(aq) + 3NaOH(aq) - Fe(OH)3(s) + 3NaCl(aq) What is the ionic equation for this…
Answer this question and get it marked →A compound is analysed and found to contain 85.7% carbon and 14.3% hydrogen only. What is its empirical formula? A CH B CH2 C C2H4 D C6H
Answer this question and get it marked →Aqueous barium hydroxide, Ba(OH)2, reacts with dilute nitric acid, HNO3. The products are aqueous barium nitrate, Ba(NO3)2, and water. In a titration, 15.2 cm3 of 0.75 mol/dm3…
Answer this question and get it marked →Which particles are responsible for the transfer of charge in the external circuit during the electrolysis of molten lead(II) bromide? A anions B atoms C cations D electrons
Answer this question and get it marked →Two statements about hydrogen are listed. 1 Hydrogen is used as a fuel. 2 When hydrogen burns in the air to form water, thermal energy is produced. Which conclusion about these…
Answer this question and get it marked →Concentrated aqueous copper(II) chloride is electrolysed using carbon electrodes. What is formed at each electrode? negative electrode positive electrode --- --- --- A chlorine…
Answer this question and get it marked →Which row describes an exothermic reaction? sign of enthalpy change, deltaH temperature of the surroundings --- --- --- A positive decreases B positive increases C negative…
Answer this question and get it marked →A reaction pathway diagram is shown. The diagram plots energy against progress of reaction. The reactants are at a higher energy level than the products. The curve rises to a peak…
Answer this question and get it marked →The rate of reaction between magnesium and dilute hydrochloric acid is increased by increasing the concentration of the acid. How does this affect the reacting particles?…
Answer this question and get it marked →The reaction between aqueous iron(III) ions, Fe3+, and aqueous thiocyanate ions, SCN-, is reversible. The equation for the reaction is shown. Fe3+(aq) + SCN-(aq) <= FeSCN2+(aq)…
Answer this question and get it marked →The equation for the reaction between iron(II) sulfate and bromine is shown. 6FeSO4 + 3Br2 - 2Fe2(SO4)3 + 2FeBr3 Which row identifies the oxidising agent and the reducing agent?…
Answer this question and get it marked →The equation represents a redox reaction. 2Al + Fe2O3 - 2Fe + Al2O3 What is the change in the oxidation number of iron in this reaction? A from +2 to +3 B from +2 to 0 C from +3…
Answer this question and get it marked →Aqueous ammonia forms an equilibrium with water. NH3 + H2O <= NH4+ + OH- In this equilibrium, which particle acts as an acid and which particle acts as a base? acid base --- ---…
Answer this question and get it marked →Which row identifies an acidic oxide, a basic oxide and an amphoteric oxide? acidic basic amphoteric --- --- --- --- A ZnO SO2 Al2O3 B SO2 Al2O3 Na2O C ZnO Al2O3 SO2 D SO2 Na2O…
Answer this question and get it marked →A Group I metal (lithium or potassium) is reacted with a Group VII element (chlorine or iodine). Which compound is formed when the Group I metal of highest density reacts with the…
Answer this question and get it marked →Element X is in the same group of the Periodic Table as silicon. An atom of element X has more protons than a silicon atom. Which element could be X? A aluminium B carbon C…
Answer this question and get it marked →Which statement about the elements in Group VIII is correct? A They all form diatomic molecules. B They all have eight electrons in their outer electron shells. C They all react…
Answer this question and get it marked →Which element is a transition element? The options give the melting point, density at r.t.p. and colour of oxide at r.t.p. for each row. melting point in degrees C density at…
Answer this question and get it marked →Four test-tubes contain dilute hydrochloric acid. Each test-tube has one piece of a different metal added to it. The metals are copper, iron, magnesium and zinc. The diagrams A to…
Answer this question and get it marked →Brass is a mixture of copper and zinc. Which statement describes and explains the relative strength of brass compared to copper? A Brass is stronger than copper because the layers…
Answer this question and get it marked →A sample of calcium carbonate is heated strongly, and substances U and V are formed. Substance U is a white solid. Substance V is a colourless gas. What are substances U and V? U…
Answer this question and get it marked →A sample of water taken from a river contains harmful microbes. What is a source of harmful microbes in the river water? A sewage B fertilisers C detergents D plastics
Answer this question and get it marked →Anhydrous copper(II) sulfate and anhydrous cobalt(II) chloride change colour when water is added to them. Which row shows the correct colour changes? copper(II) sulfate cobalt(II)…
Answer this question and get it marked →Which gas contributes to increased global warming? A argon B carbon dioxide C nitrogen D oxygen
Answer this question and get it marked →Which statement describes how greenhouse gases increase global warming? A Greenhouse gases absorb thermal energy from the Sun, reducing the Earth's temperature. B Greenhouse gases…
Answer this question and get it marked →Nitrogen monoxide is produced in a car engine when petrol is burned. The gases from the car engine are passed through a catalytic converter. In the catalytic converter, the…
Answer this question and get it marked →The displayed formula of but-2-ene is shown: a four-carbon chain CH3-CH=CH-CH3 with a carbon-carbon double bond between the second and third carbon atoms. Which displayed formulae…
Answer this question and get it marked →Which row describes two characteristics of members of the same homologous series? characteristic 1 characteristic 2 --- --- --- A same functional group trend in physical…
Answer this question and get it marked →Compound W is a hydrocarbon that contains single bonds only. Which homologous series contains W? A alkenes B alkanes C carboxylic acids D alcohols
Answer this question and get it marked →Methane forms chloromethane in a photochemical reaction using ultraviolet light. Which statement about this reaction is correct? A Methane is mixed with hydrogen chloride gas, and…
Answer this question and get it marked →Which statement about polymers is correct? A Nylon contains the amide linkage -C(=O)-N(H)- (a carbonyl carbon bonded to a nitrogen carrying a hydrogen). B Nylon is a polyester. C…
Answer this question and get it marked →The steps used to separate a mixture of a soluble solid and an insoluble solid are listed. - A solution is made by adding the mixture to a suitable ...1... . - The mixture is…
Answer this question and get it marked →Which items of apparatus are used to separate a mixture of liquids with different boiling points? Four sets of apparatus are shown: A a distillation set-up (round-bottomed flask…
Answer this question and get it marked →In paper chromatography, what is the equation for the Rf value? A Rf = (distance travelled by solvent) / (distance travelled by substance) B Rf = (distance travelled by locating…
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