0620 Chemistry November 2025 Question Paper 22

What happens to the volume of a fixed mass of gas when the temperature is increased or the pressure is decreased? increased temperature decreased pressure

The diagram shows the heating curve for a substance. temperature time Q P R S T U Between which two points do the particles of the substance change from being in fixed positions to being mobile?

A student investigates the diffusion of ammonia gas, NH3, and hydrogen chloride gas, HCl. Two sets of apparatus are set up as shown at room temperature and pressure. apparatus 1 source of ammonia gas damp red litmus paper apparatus 2 source of hydrogen chloride gas damp blue litmus paper The damp red litmus paper in apparatus 1 changes colour after 30 seconds. How long does it take for the damp blue litmus paper in apparatus 2 to change colour?

Which row describes elements, compounds and mixtures? elements compounds mixtures

Which statement about atoms or ions is correct?

Which two values are used to calculate the relative atomic mass of a sample of boron? value 1 value 2

Which statement describes the structure of sodium chloride?

Graphite and diamond are both forms of the element carbon. Which row shows the number of other carbon atoms that each carbon atom is covalently bonded to in graphite and in diamond? graphite diamond

Which row describes the structure and bonding in cobalt? structure bonding

The equation for the combustion of ethanol is shown. C2H5OH + 3O2  2CO2 + 3H2O The relative molecular mass, Mr, of ethanol is 46. Which statement about the reaction is correct?

A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen only. The relative molecular mass, Mr, of the compound is 60. Which row shows the empirical formula and the molecular formula of the compound? empirical formula molecular formula

Hydrogen–oxygen fuel cells are used in electric cars. Three statements about these fuel cells are listed. The process in the cell is called electrolysis. Water is broken down in the cell to produce hydrogen, oxygen and electricity. Water is the only chemical product formed in the reaction. Which statements are correct?

A solution of copper(II) sulfate can be electrolysed using copper electrodes or carbon electrodes. Which statements are correct? Using copper electrodes, oxygen gas forms at the anode. Using copper electrodes, copper atoms lose electrons at the anode. Using carbon electrodes, copper metal forms at the cathode. Using carbon electrodes, copper ions gain electrons at the cathode.

The equation for the combustion of hydrazine, N2H4, is shown. +
O + 2 O N N O H H N N H H H H bond bond energy in kJ / mol N–H 391 N=N 409 N≡N 944 O–H 463 O=O 496 What is the overall enthalpy change for the combustion of one mole of hydrazine?

Dissolving ammonium chloride in water is an endothermic change. Which row shows the energy change and temperature change of the mixture during the dissolving of ammonium chloride? energy change temperature change

Aqueous sodium thiosulfate, Na2S2O3, reacts with dilute hydrochloric acid to form a yellow precipitate of sulfur. Na2S2O3(aq) + 2HCl (aq)  2NaCl (aq) + H2O(l) + S(s) + SO2(g) The precipitate forms more quickly when the reactants are heated. Which statements explain this observation? The reacting particles collide more frequently. The collisions between reacting particles have more energy. The activation energy of the reaction is lower.

Which statement about the conditions used in the Haber process and in the Contact process is correct?

The equation shows the equilibrium between dinitrogen tetroxide, N2O4, and nitrogen dioxide, NO2. The colours of the reactant and product are shown. N2O4(g) 2NO2(g) colourless brown The forward reaction is endothermic. Which statement is not correct?

What is the oxidation number of chromium in the Cr2O7 2– ion?

Which method is used to prepare a pure, dry sample of lead(II) chloride?

Phosphorus is an element in Group V of the Periodic Table. It burns in air to form an oxide that dissolves in water to form a solution with a pH of 1. Which row describes this oxide of phosphorus? metal oxide non-metal oxide acidic oxide basic oxide

The equation shows the reaction between aqueous hydrogen bromide and aqueous ammonia. HBr(aq) + NH3(aq)  NH4 +(aq) + Br –(aq) Which statement describes the role of aqueous hydrogen bromide?

Which statement about the elements in Group I is correct?

Which row describes the colour and state of iodine at room temperature and pressure? colour state

Part of the Periodic Table is shown. Which element is an inert gas?

Four different metals are separately added to water. The oxide of each metal is separately heated with carbon. The results are shown. metal metal with water metal oxide with carbon Q no reaction brown solid forms R rapid fizzing no reaction S a few bubbles no reaction T a few bubbles grey solid forms What is the order of reactivity of the four metals, least reactive first?

An iron nail is fully covered with zinc to prevent it from rusting. Which row describes this method of protection and explains why zinc is used to protect the iron nail? method of protection reason zinc is used

Iron is extracted from hematite in the blast furnace. Which reaction increases the temperature in the blast furnace to over 1500 °C?

Aluminium is extracted by the electrolysis of purified bauxite. Which row shows the half-equations at the electrodes and explains why one of the electrodes has to be replaced regularly? half-equation at anode half-equation at cathode electrode replacement

Which flow chart describes the correct treatment sequence of the domestic water supply?

Which statement about oxides of nitrogen is correct?

The alkenes are a homologous series. Which statement about the members of the homologous series of the alkenes is correct?

The diagram represents two processes, X and Y, and their effect, Z, in increasing global warming. emission of thermal energy from the Earth X Y Z Which row identifies X, Y and Z? X Y Z

Which structures are structural isomers of each other? H

The structure of an ester is shown. H

Which row shows the products obtained by the cracking of a large alkane? alkene hydrogen water

Ethanol is produced by the fermentation of aqueous glucose or by the catalytic addition of steam to ethene. Which row shows some advantages and disadvantages of these processes? fermentation of aqueous glucose catalytic addition of steam to ethene advantage disadvantage advantage disadvantage

Propenoic acid is an organic compound that is both an alkene and a carboxylic acid. The structure of propenoic acid is shown.

Which item of apparatus is used to measure 13.7 cm3 of dilute hydrochloric acid?

Chromatography is used to separate and analyse mixtures of soluble substances. The first steps of the process are listed. ● apply sample to baseline ● develop chromatogram in solvent What is the next step in the process to detect soluble colourless substances?