WJEC A-Level Chemistry AS Unit 1, June 2025
Every question from WJEC A-Level Chemistry AS Unit 1, June 2025 (2410): 13 questions, 80 marks, each with its mark scheme and topic.
- Question 1 1 mark
Draw a dot and cross diagram using outer electrons only to show the bonding in a diatomic molecule of oxygen.
Physical Chemistry · 1.4 Bonding
- Question 2 1 mark
State why the coordination number of Na⁺ in NaCl differs from that of Cs⁺ in CsCl.
Physical Chemistry · 1.4 Bonding · 1.5 Solid structures
- Question 3 1 mark
Compare the frequency and transition energy of spectral lines in the visible emission spectrum of hydrogen using the terms higher or lower.
Physical Chemistry · 1.2 Basic ideas about atoms
- Question 4 1 mark
Deduce the formula of the chloride of element X using its first four successive ionisation energies.
Physical Chemistry · 1.2 Basic ideas about atoms
- Question 5 1 mark
State the total number of occupied orbitals in a nitrogen atom.
Physical Chemistry · 1.2 Basic ideas about atoms
- Question 6 2 marks
Identify the s-block element that forms the least soluble sulfate and the element whose compounds produce an apple-green flame test.
Inorganic Chemistry · 1.6 The Periodic Table
- Question 7 1 mark
Write the chemical formula of magnesium hydrogencarbonate given the formula of the hydrogencarbonate ion.
Physical Chemistry · Inorganic Chemistry · 1.1 Formulae and equations · 1.4 Bonding · 1.6 The Periodic Table
- Question 8 2 marks
Calculate the number of nitrogen atoms present in 66.0 g of dinitrogen monoxide, N2O.
Physical Chemistry · 1.3 Chemical calculations
- Question 9 15 marks
Identify mass spectrometer components, plot a mass spectrum for lead isotopes, determine radioactive decay and half-life of radon, and calculate the relative atomic mass of radium from precipitation data.
Physical Chemistry · 1.2 Basic ideas about atoms · 1.3 Chemical calculations
- Question 10 13 marks
Determine the water of crystallisation in hydrated strontium chloride from thermal decomposition data, calculate percentage error, predict experimental effects, and suggest improvements.
Physical Chemistry · Practical · 1.3 Chemical calculations · AS Unit 1 practical work
- Question 11 14 marks
Explain trends in boiling temperatures of Group 5 hydrides, use VSEPR theory to deduce the shape and bond angle of PH3, evaluate qualitative tests for halides, and explain a redox reaction using oxidation states.
Physical Chemistry · Inorganic Chemistry · 1.4 Bonding · 1.6 The Periodic Table · 1.1 Formulae and equations
- Question 12 15 marks
Deduce the structure of lithium hydride, determine stoichiometric ratios and an equation for the thermal decomposition of lithium aluminium hydride, calculate the volume of hydrogen gas formed from lithium reacting with water, and calculate the equilibrium constant Kc and equilibrium concentration of methane.
Physical Chemistry · Inorganic Chemistry · 1.1 Formulae and equations · 1.3 Chemical calculations · 1.4 Bonding · 1.5 Solid structures · 1.7 Simple equilibria and acid-base reactions
- Question 13 13 marks
Describe a back titration method to determine the relative formula mass of calcium carbonate, explain acid-base properties, and carry out dilution and pH calculations.
Physical Chemistry · Practical · 1.3 Chemical calculations · 1.7 Simple equilibria and acid-base reactions · AS Unit 1 practical work