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Exam Review

Key Facts: Catalonia PAU Chemistry Exam

EUR 110.00+ access phase (EUR 41.30 exam right + EUR 68.70 access phase; plus EUR 13.80 per admission exercise, Generalitat de Catalunya 2026)

Base registration fee set by Generalitat de Catalunya

Generalitat de Catalunya PAU Rules

90 Mins

Official examination duration

Consell Interuniversitari de Catalunya (CIC)

Min 4.0

Minimum Access Phase score required to combine with Bachillerato GPA

CIC Catalonia PAU Guidelines

7 Blocks

Core chemistry syllabus units

2n Batxillerat LOMLOE Chemistry Curriculum

100

Practice questions available in this OpenExamPrep bank

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Master Catalonia PAU Chemistry (Química 2n Batxillerat) with 100 realistic practice questions and complete numerical step-by-step solutions.

Sample Catalonia PAU Chemistry Practice Questions

Try these sample questions to review concepts for the Catalonia PAU Chemistry exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which set of quantum numbers (n, l, ml, ms) represents a valid valence electron in the highest-energy populated orbital of a ground-state chlorine atom (Z = 17)?
A.(3, 1, 0, +1/2)
B.(3, 2, 0, -1/2)
C.(2, 1, -1, +1/2)
D.(3, 0, +1, -1/2)
Explanation: Chlorine (Z = 17) has the ground-state electron configuration 1s² 2s² 2p⁶ 3s² 3p⁵. The highest-energy valence electrons reside in the 3p subshell, corresponding to principal quantum number n = 3 and azimuthal quantum number l = 1. For l = 1, magnetic quantum number ml can be -1, 0, or +1, and spin quantum number ms can be +1/2 or -1/2, making (3, 1, 0, +1/2) valid.
2What is the correct ground-state electron configuration of a neutral chromium atom (Z = 24)?
A.[Ar] 4s² 3d⁴
B.[Ar] 3d⁵ 4s¹
C.[Ar] 4s² 3d⁵
D.[Ar] 3d⁶
Explanation: Chromium (Z = 24) exhibits an anomaly to the standard Aufbau ordering because transferring one electron from the 4s orbital to the 3d subshell creates a half-filled 3d subshell ([Ar] 3d⁵ 4s¹), which confers extra exchange stability.
3How does atomic radius vary across Period 3 of the periodic table from Sodium (Na, Z = 11) to Chlorine (Cl, Z = 17)?
A.Atomic radius increases because additional electrons increase electron-electron repulsion.
B.Atomic radius remains constant because electrons are added to the same principal shell n = 3.
C.Atomic radius decreases because increasing nuclear charge increases effective nuclear charge (Zeff), pulling valence shell electrons closer.
D.Atomic radius decreases initially then increases sharp at Phosphorus due to subshell half-filling.
Explanation: Across Period 3, atomic radius decreases from Sodium to Chlorine because nuclear charge Z increases while inner-shell shielding remains nearly constant. The resulting higher effective nuclear charge (Zeff) exerts a stronger electrostatic pull on the n = 3 valence electrons, drawing them closer to the nucleus.
4Why is the first ionization energy of Magnesium (Z = 12, 738 kJ/mol) higher than that of Aluminum (Z = 13, 578 kJ/mol)?
A.Magnesium has a larger nuclear charge than Aluminum.
B.Aluminum's valence electron is removed from a higher-energy 3p subshell that is shielded by filled 3s orbitals.
C.Magnesium has a smaller atomic radius than Aluminum.
D.Aluminum forms a stable noble gas core upon losing one electron.
Explanation: Magnesium has a ground-state configuration of [Ne] 3s², whereas Aluminum is [Ne] 3s² 3p¹. The 3p electron removed during Aluminum's first ionization is higher in energy and shielded by the fully filled 3s subshell, requiring less energy to remove than a 3s electron from Magnesium.
5Why is the electron affinity of Chlorine (-349 kJ/mol) more negative (more exothermic) than that of Fluorine (-328 kJ/mol)?
A.Fluorine has a lower electronegativity than Chlorine.
B.Chlorine has a smaller nuclear charge than Fluorine.
C.Fluorine's compact 2p subshell experiences strong electron-electron repulsion, weakening the net attraction for an incoming electron.
D.Chlorine's 3p subshell can accommodate an extra electron without requiring spin pairing.
Explanation: Fluorine is extremely small, resulting in high electron density within its 2p subshell. The strong inter-electronic repulsions in this compact region partially offset the attractive force of the nucleus, making Fluorine's electron affinity slightly less exothermic than Chlorine's 3p subshell addition.
6Which of the following orders represents the correct trend of decreasing ionic radius for the isoelectronic series S²⁻, Cl⁻, K⁺, Ca²⁺?
A.Ca²⁺ > K⁺ > Cl⁻ > S²⁻
B.S²⁻ > Cl⁻ > K⁺ > Ca²⁺
C.Cl⁻ > S²⁻ > Ca²⁺ > K⁺
D.K⁺ > Ca²⁺ > S²⁻ > Cl⁻
Explanation: For an isoelectronic series (all species have 18 electrons, [Ar] configuration), ionic radius decreases as nuclear charge Z increases. S²⁻ (Z=16) has the smallest Z and largest radius, followed by Cl⁻ (Z=17), K⁺ (Z=19), and Ca²⁺ (Z=20) which has the highest nuclear charge pulling electrons tightest.
7What is the energy of a single photon of ultraviolet radiation with a wavelength of λ = 250 nm? (Planck's constant h = 6.63 × 10⁻³⁴ J·s, speed of light c = 3.00 × 10⁸ m/s)
A.7.96 × 10⁻¹⁹ J
B.1.66 × 10⁻³¹ J
C.4.97 × 10⁻¹⁹ J
D.2.65 × 10⁻²⁷ J
Explanation: Using E = hc/λ: λ = 250 × 10⁻⁹ m. E = (6.63 × 10⁻³⁴ J·s × 3.00 × 10⁸ m/s) / (250 × 10⁻⁹ m) = 1.989 × 10⁻²⁵ / 2.50 × 10⁻⁷ = 7.956 × 10⁻¹⁹ J ≈ 7.96 × 10⁻¹⁹ J.
8In the hydrogen atom emission spectrum, what is the wavelength of the light emitted during the Balmer series transition from n = 3 to n = 2? (Rydberg constant R_H = 1.097 × 10⁷ m⁻¹)
A.434 nm
B.656 nm
C.486 nm
D.122 nm
Explanation: Using the Rydberg equation 1/λ = R_H (1/n1² - 1/n2²): 1/λ = 1.097 × 10⁷ (1/4 - 1/9) = 1.097 × 10⁷ (5/36) = 1.5236 × 10⁶ m⁻¹. Inverting gives λ = 6.563 × 10⁻⁷ m = 656 nm (H-alpha red visible line).
9What is the de Broglie wavelength of an electron (mass m = 9.11 × 10⁻³¹ kg) moving at a velocity of 2.00 × 10⁶ m/s? (h = 6.63 × 10⁻³⁴ J·s)
A.3.64 × 10⁻¹⁰ m
B.1.21 × 10⁻⁹ m
C.7.28 × 10⁻¹¹ m
D.5.47 × 10⁻⁷ m
Explanation: According to de Broglie's equation λ = h / (m·v): λ = (6.63 × 10⁻³⁴ J·s) / (9.11 × 10⁻³¹ kg × 2.00 × 10⁶ m/s) = 6.63 × 10⁻³⁴ / 1.822 × 10⁻²⁴ = 3.64 × 10⁻¹⁰ m (0.364 nm).
10An element X in Period 3 has the following successive ionization energies (in kJ/mol): IE1 = 578, IE2 = 1817, IE3 = 2745, IE4 = 11577, IE5 = 14842. To which group of the periodic table does element X belong?
A.Group 1 (Alkali metals)
B.Group 2 (Alkaline earth metals)
C.Group 13 (Boron group)
D.Group 14 (Carbon group)
Explanation: A dramatic spike occurs between IE3 (2745 kJ/mol) and IE4 (11577 kJ/mol), over a 4-fold increase. This indicates that element X has 3 valence electrons. Removing the 4th electron requires breaking into a stable noble gas core, identifying element X as Aluminum in Group 13.

About the Catalonia PAU Chemistry Exam

The Catalonia PAU Chemistry examination (Proves d'Accés a la Universitat) is organized by the Consell Interuniversitari de Catalunya (CIC) for 2n de Batxillerat students. While the official exam consists of structured written calculations and problem-solving questions presented in Catalan and Spanish, this question bank offers an English-language multiple-choice adaptation covering all core curriculum blocks: Atomic Structure, Chemical Bonding, Thermochemistry, Chemical Equilibrium, Acid-Base, Electrochemistry, and Organic Chemistry.

Exam sponsor: Consell Interuniversitari de Catalunya (CIC) / Generalitat de Catalunya. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Written 90-minute examination with structured numerical problems and chemical reasoning questions. Note: The official exam is administered in Catalan and Spanish; these practice questions provide an English-language multiple-choice study adaptation.

Time Limit

90 minutes

Passing Score

Marked on a 0-10 scale. Minimum 4.0 required in Access Phase to combine with Bachillerato GPA (60% Bachillerato + 40% PAU Access Phase >= 5.0 to pass).

Exam / Certification Fees

EUR 41.30 examination right + EUR 68.70 access phase + EUR 13.80 per admission-phase exercise (Generalitat de Catalunya, PAU 2026); 50% reduction and full exemption available for eligible groups

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

15%

Atomic Structure & Periodic Properties

Quantum numbers, electron configurations, periodic trends (ionization energy, electron affinity, electronegativity, atomic radius), and photon energy calculations.

15%

Chemical Bonding & Molecular Structure

Ionic bonding & lattice energy (Born-Haber cycle), covalent bonding (Lewis structures, VSEPR theory, hybridization), metallic bonding, and intermolecular forces.

15%

Thermodynamics & Thermochemistry

Reaction enthalpy (Hess's law, standard formation enthalpies), entropy, Gibbs free energy, reaction spontaneity, and temperature dependence.

15%

Chemical Equilibrium & Solubility

Equilibrium constants (Kc, Kp, relation Kp = Kc(RT)^dn), reaction quotient Q, Le Chatelier's principle, solubility product (Ksp), and common ion effect.

15%

Acid-Base Equilibria & pH Calculations

Brønsted-Lowry & Lewis concepts, pH/pOH of strong/weak acids and bases, salt hydrolysis, buffer solutions (Henderson-Hasselbalch), and volumetric titrations.

15%

Redox Reactions & Electrochemistry

Oxidation numbers, balancing redox reactions (ion-electron method), galvanic cell potentials (E°cell), Nernst equation, Gibbs energy (ΔG° = -nFE°), and Faraday's laws of electrolysis.

10%

Organic Chemistry & Functional Groups

IUPAC nomenclature, functional groups, structural/geometric/optical isomerism, reaction types (addition, substitution, elimination, esterification), and oxidation states.

Preparing for the Catalonia PAU Chemistry Exam

What You Need to Know

  • Passing score: Marked on a 0-10 scale. Minimum 4.0 required in Access Phase to combine with Bachillerato GPA (60% Bachillerato + 40% PAU Access Phase >= 5.0 to pass).
  • Assessment: Written 90-minute examination with structured numerical problems and chemical reasoning questions. Note: The official exam is administered in Catalan and Spanish; these practice questions provide an English-language multiple-choice study adaptation.
  • Time limit: 90 minutes
  • Exam / certification fees: EUR 41.30 examination right + EUR 68.70 access phase + EUR 13.80 per admission-phase exercise (Generalitat de Catalunya, PAU 2026); 50% reduction and full exemption available for eligible groups Official sources

Using Our Practice Resources

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

Catalonia PAU Chemistry: Suggested Study Strategy

1Master step-by-step stoichiometric calculations and pay close attention to units, gas constants, and significant figures.
2Practice thermochemical calculations using Hess's Law and Gibbs free energy (ΔG = ΔH - TΔS).
3Ensure fluency in converting between equilibrium constants Kc and Kp using Kp = Kc(RT)^Δn.
4Practice pH calculations for weak acids/bases, salt hydrolysis, and buffer systems using equilibrium expressions.
5Review redox ion-electron balancing methods in acidic and basic media alongside Faraday's laws of electrolysis.

Frequently Asked Questions

What is the format of the official Catalonia PAU Chemistry exam?

The official Catalonia PAU Chemistry exam is a 90-minute written examination administered in Catalan and Spanish. The 100 practice questions on this platform provide an English-language multiple-choice study adaptation designed to help students master core 2nd Bachillerato curriculum concepts.

What is the passing score for Catalonia PAU Chemistry?

The exam is graded on a 0–10 scale. In the Access Phase (Fase de Acceso), a minimum score of 4.0 is required to average with the Bachillerato GPA (which counts for 60% of the final university access score, while PAU counts for 40%, requiring a total average of >= 5.0).

What is the fee for taking the PAU exam in Catalonia?

The Generalitat de Catalunya, through the Consell Interuniversitari de Catalunya (CIC), sets the 2026 PAU ordinary fees at EUR 41.30 examination right, EUR 68.70 access phase, and EUR 13.80 per admission-phase exercise. A 50% reduction and a full exemption are available for eligible groups such as large families (família nombrosa general), scholarship holders, and students with a recognised disability of 33% or more.