OCR A-Level Chemistry AS Breadth in chemistry (01), June 2025
Every question from OCR A-Level Chemistry AS Breadth in chemistry (01), June 2025 (H032): 25 questions, 70 marks, each with its mark scheme and topic.
- Question 1 1 mark
Calculate the percentage uncertainty of a titre obtained from initial and final burette readings, given the uncertainty of each reading.
Module 1: Development of practical skills in chemistry · Practical Activity Groups · 1.1 Practical skills assessed in a written examination · PAG 2: Acid-base titration
- Question 2 1 mark
Determine the number of p electrons in an atom of chlorine.
Module 2: Foundations in chemistry · 2.2 Electrons, bonding and structure
- Question 3 1 mark
Calculate the total number of hydrogen atoms present in 6.8 g of ammonia.
Module 2: Foundations in chemistry · 2.1 Atoms and reactions
- Question 4 1 mark
Identify which reaction to extract iron has the highest atom economy.
Module 2: Foundations in chemistry · 2.1 Atoms and reactions
- Question 5 1 mark
Identify which phosphorus oxide has the closest composition to 50% by mass of phosphorus.
Module 2: Foundations in chemistry · 2.1 Atoms and reactions
- Question 6 1 mark
Determine the oxidation number of sulfur in sodium thiosulfate, Na₂S₂O₃.
Module 2: Foundations in chemistry · 2.1 Atoms and reactions
- Question 7 1 mark
Identify which reaction from a given list of chemical equations is not a redox reaction.
Module 2: Foundations in chemistry · 2.1 Atoms and reactions
- Question 8 1 mark
Identify which of the given chloride compounds possesses molecules with a trigonal planar shape.
Module 2: Foundations in chemistry · 2.2 Electrons, bonding and structure
- Question 9 1 mark
Identify the equation that represents the second ionisation energy of magnesium.
Module 3: Periodic table and energy · 3.1 The periodic table
- Question 10 1 mark
Identify which of the given molecules (H2S, CO2, CCl4, or C2F4) is polar.
Module 2: Foundations in chemistry · 2.2 Electrons, bonding and structure
- Question 11 1 mark
Calculate the standard enthalpy change of combustion of methanol from standard enthalpy changes of formation.
Module 3: Periodic table and energy · 3.2 Physical chemistry
- Question 12 1 mark
Identify the effect of increasing pressure on the rate of reaction and equilibrium yield of HI for the reaction H2(g) + I2(g) ⇌ 2HI(g).
Module 3: Periodic table and energy · 3.2 Physical chemistry
- Question 13 1 mark
Identify which statement is not a sustainability benefit of an industrial process using a catalyst.
Module 3: Periodic table and energy · 3.2 Physical chemistry
- Question 14 1 mark
Identify which pair of alcohols from the given skeletal formulae are structural isomers of each other.
Module 4: Core organic chemistry · 4.1 Basic concepts and hydrocarbons · 4.2 Alcohols, haloalkanes and analysis
- Question 15 1 mark
Identify the systematic IUPAC name and stereochemistry (E/Z isomerism) of a given fluoroalkene.
Module 4: Core organic chemistry · 4.1 Basic concepts and hydrocarbons
- Question 16 1 mark
Identify which equation represents a propagation step in the catalytic breakdown of ozone.
Module 4: Core organic chemistry · 4.2 Alcohols, haloalkanes and analysis
- Question 17 1 mark
Determine the number of structural isomers of C5H12O that are secondary alcohols.
Module 4: Core organic chemistry · 4.1 Basic concepts and hydrocarbons · 4.2 Alcohols, haloalkanes and analysis
- Question 18 1 mark
Identify the statement that explains why 1-iodopropane hydrolyses faster than 1-bromopropane.
Module 4: Core organic chemistry · 4.2 Alcohols, haloalkanes and analysis
- Question 19 1 mark
Identify which alkene is likely to produce a fragment ion at m/z = 29 in its mass spectrum.
Module 4: Core organic chemistry · 4.2 Alcohols, haloalkanes and analysis · 4.1 Basic concepts and hydrocarbons
- Question 20 1 mark
Identify which compound corresponds to the given infrared spectrum showing a strong absorption around 1720–1740 cm⁻¹ and no broad O–H peak.
Module 4: Core organic chemistry · 4.2 Alcohols, haloalkanes and analysis
- Question 21 13 marks
Analyze isotopes of sulfur and magnesium, draw and explain metallic bonding in magnesium, and determine the concentration of hydrochloric acid and collision theory factors from reaction rate gas collection data.
Module 2: Foundations in chemistry · Module 3: Periodic table and energy · Module 1: Development of practical skills in chemistry · Practical Activity Groups · 2.1 Atoms and reactions · 2.2 Electrons, bonding and structure · 3.2 Physical chemistry · 1.1 Practical skills assessed in a written examination · PAG 9: Rates of reaction – continuous monitoring method
- Question 22 11 marks
Explain disproportionation using oxidation numbers in bromine's reaction with alkali, explain why chlorine is more reactive than bromine, state a risk of water chlorination, and describe qualitative tests to identify halide ions.
Module 2: Foundations in chemistry · Module 3: Periodic table and energy · Practical Activity Groups · 2.1 Atoms and reactions · 3.1 The periodic table · PAG 4: Qualitative analysis of ions
- Question 23 8 marks
State the features of dynamic equilibrium, calculate the S=O bond enthalpy in sulfur trioxide, and determine the equilibrium constant Kc.
Module 3: Periodic table and energy · 3.2 Physical chemistry
- Question 24 9 marks
Draw repeat units, assess disposal, write a combustion equation, outline the electrophilic addition mechanism with HCl, and explain carbocation stability for alkenes.
Module 4: Core organic chemistry · Module 2: Foundations in chemistry · 4.1 Basic concepts and hydrocarbons · 2.1 Atoms and reactions
- Question 25 9 marks
Identify oxidation products, elimination behaviour, and calculate the volume of carbon dioxide produced from the combustion of isomeric alcohols using the ideal gas equation.
Module 4: Core organic chemistry · Module 2: Foundations in chemistry · 4.2 Alcohols, haloalkanes and analysis · 2.1 Atoms and reactions