Chemistry practice questions by topic, in exam style

Original questions for every topic in Paper 1A and 1B style, with full working.

Paper 1A	Multiple choice, about 2 minutes a question in our timed sets
Paper 1B	Data-based questions: experiments, tables, graphs and uncertainties
Levels	Every question is tagged SL or HL

Try 5 questions

Question 1

Proposed orbital diagram for nitrogen. 1s orbital: two electrons with opposite spins. 2s orbital: two electrons with opposite spins. First 2p orbital: two electrons with opposite spins. Second 2p orbital: one electron. Third 2p orbital: empty.
1s	2s	2p (first)	2p (second)	2p (third)
↑↓	↑↓	↑↓	↑	empty

The table shows a proposed arrangement of the seven electrons of a nitrogen atom in orbitals, with arrows for electron spins. Which statement about it is correct?

Question 2

Ionic radii in pm: Na⁺ 102, K⁺ 138, Mg²⁺ 72, F⁻ 133, Cl⁻ 181, O²⁻ 140.
Ion	Ionic radius / pm
Na⁺	102
K⁺	138
Mg²⁺	72
F⁻	133
Cl⁻	181
O²⁻	140

The table gives the radii of some ions. Which compound has the largest lattice enthalpy?

Question 3

The graph shows the atomic radii of the elements from sodium (Z = 11) to chlorine (Z = 17) in period 3. Which statement explains the trend?

Question 4

Ethene reacts with hydrogen as shown: C₂H₄(g) + H₂(g) → C₂H₆(g). Average bond enthalpies in kJ mol⁻¹: C=C 614, C-C 346, C-H 414, H-H 436. What is ΔH for the reaction?

Question 5

Table of results. W added to X²⁺(aq): reaction; W added to Y²⁺(aq): reaction. X added to W²⁺(aq): no reaction; X added to Y²⁺(aq): no reaction. Y added to W²⁺(aq): no reaction; Y added to X²⁺(aq): reaction.
Metal added	W²⁺(aq)	X²⁺(aq)	Y²⁺(aq)
W	not tested	reaction	reaction
X	no reaction	not tested	no reaction
Y	no reaction	reaction	not tested

A student adds pieces of three metals, W, X and Y, to solutions of their ions, as in the table. What is the order of reactivity, most reactive first?

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The current course was first assessed in 2025, in Structure 1 to 3 and Reactivity 1 to 3. Check older questions against the current topics.