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Exam Review

Key Facts: PAU Chemistry (Cantabria) Exam

90 min

Exam time duration for the PAU Chemistry paper

University of Cantabria (UNICAN) PAU Organising Commission

4 Apartados

Compulsory written exam sections, each worth 2.5 of 10 points

UNICAN Chemistry Orientations

0–10 scale

Scoring system (minimum 4.0 required in Access Phase)

Cantabria PAU Regulations

5 Blocks

Core Bachillerato curriculum blocks evaluated in the exam

Real Decreto 243/2022 (LOMLOE)

100

High-quality practice questions in this OpenExamPrep subject bank

OpenExamPrep

Master the 2026 Cantabria PAU Chemistry exam with 100 practice questions covering atomic structure and bonding, thermochemistry, chemical equilibrium, acid-base/redox, and organic chemistry. This English-language MCQ bank is a study adaptation of the theory and calculation knowledge behind the official written exam.

Sample PAU Chemistry (Cantabria) Practice Questions

Try these sample questions to review concepts for the PAU Chemistry (Cantabria) 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) is permissible for an electron occupying a 3d orbital in an atom's ground state?
A.(3, 2, -1, +1/2)
B.(3, 1, +2, -1/2)
C.(3, 3, 0, +1/2)
D.(2, 2, -1, -1/2)
Explanation: For a 3d orbital, the principal quantum number is n = 3 and the azimuthal quantum number is l = 2. The magnetic quantum number ml can range from -l to +l, so ml = -1 is valid, and ms can be +1/2 or -1/2. Therefore, (3, 2, -1, +1/2) satisfies all quantum rules.
2What is the ground-state electron configuration of the neutral copper atom (Z = 29)?
A.[Ar] 4s² 3d⁹
B.[Ar] 4s¹ 3d¹⁰
C.[Ar] 4s⁰ 3d¹⁰
D.[Ar] 4s² 3d¹⁰
Explanation: Copper exhibits an exception to the standard Aufbau ordering by promoting one electron from 4s to 3d. This complete 3d¹⁰ subshell provides enhanced exchange energy stability. Thus, its ground-state configuration is [Ar] 4s¹ 3d¹⁰.
3How does the atomic radius generally change across Period 3 of the periodic table from sodium (Na) to chlorine (Cl)?
A.It increases because electrons are added to higher energy shells with larger principal quantum numbers.
B.It remains constant because the added protons and electrons cancel out each other's effects completely.
C.It decreases because the effective nuclear charge increases while inner shielding remains nearly constant.
D.It decreases because atomic mass decreases across the period from left to right.
Explanation: Moving from Na to Cl across Period 3, protons are added to the nucleus while valence electrons fill the same n = 3 shell. Inner-core shielding stays constant, so the effective nuclear charge Z* increases. This stronger attraction pulls valence electrons closer, decreasing atomic radius.
4Which element has the highest first ionization energy among oxygen (O), fluorine (F), nitrogen (N), and neon (Ne)?
A.Fluorine (F)
B.Nitrogen (N)
C.Oxygen (O)
D.Neon (Ne)
Explanation: First ionization energy generally increases from left to right across a period due to increasing effective nuclear charge. Noble gases have completed electron octets (2s² 2p⁶), making neon the most stable and difficult element to ionize in Period 2. Therefore, neon has the highest first ionization energy.
5Which molecule serves as a classic example of an incomplete octet on the central atom in its ground-state Lewis structure?
A.BF₃
B.NH₃
C.CH₄
D.H₂O
Explanation: In boron trifluoride (BF₃), the central boron atom has only three valence electrons. Boron forms three single covalent bonds with fluorine atoms, surrounded by six valence electrons. This leaves boron with an electron-deficient incomplete octet.
6Why is carbon dioxide (CO₂) nonpolar despite possessing polar carbon-oxygen double bonds?
A.CO₂ has a bent molecular geometry that creates asymmetric charge distribution across the oxygen atoms.
B.CO₂ has a linear geometry (sp hybridization), so its two equal C=O bond dipole vectors point in opposite directions and cancel completely.
C.The electronegativity difference between carbon and oxygen is zero, making the individual bonds nonpolar.
D.CO₂ exists as an ionic crystal lattice at room temperature where dipoles cannot exist.
Explanation: Carbon dioxide has a central sp-hybridized carbon atom forming a linear O=C=O structure (180° bond angle). Although each C=O bond is polar due to oxygen's higher electronegativity, the two equal bond dipole vectors are oriented anti-parallel. Thus, the net molecular dipole moment cancels to zero.
7What 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? (Planck's constant h = 6.626 × 10⁻³⁴ J·s)
A.1.82 × 10⁻¹⁰ m
B.7.27 × 10⁻¹⁰ m
C.3.64 × 10⁻¹⁰ m
D.5.45 × 10⁻⁹ m
Explanation: According to de Broglie's relation λ = h / (m · v), momentum determines wavelength. Substituting the given values yields λ = (6.626 × 10⁻³⁴) / ((9.11 × 10⁻³¹) × (2.00 × 10⁶)) = 3.637 × 10⁻¹⁰ m. This corresponds to 0.364 nm, which falls in the X-ray wavelength range.
8Which transition metal ion is paramagnetic with exactly 5 unpaired electrons in its ground state?
A.Cu²⁺ (Z = 29)
B.Zn²⁺ (Z = 30)
C.Ti³⁺ (Z = 22)
D.Fe³⁺ (Z = 26)
Explanation: Neutral iron (Z = 26) has configuration [Ar] 4s² 3d⁶. When forming Fe³⁺, two 4s electrons and one 3d electron are lost, yielding [Ar] 3d⁵. By Hund's rule, all 5 d-orbitals are singly occupied with parallel spins, producing 5 unpaired electrons and strong paramagnetism.
9According to VSEPR theory, what is the molecular geometry and approximate bond angle of ammonia (NH₃)?
A.Trigonal pyramidal geometry with bond angles of approximately 107°
B.Tetrahedral geometry with bond angles of exactly 109.5°
C.Trigonal planar geometry with bond angles of exactly 120°
D.T-shaped geometry with bond angles of approximately 90°
Explanation: Ammonia has four electron domains around central nitrogen (three N-H single bonds and one lone pair), adopting a tetrahedral electron domain geometry. Because lone pair-bonding pair repulsions are stronger than bonding pair-bonding pair repulsions, the H-N-H bond angles compress from 109.5° to ~107°. This produces a trigonal pyramidal molecular geometry.
10Comparing magnesium oxide (MgO) and sodium chloride (NaCl), why is the lattice energy of MgO significantly larger than that of NaCl?
A.MgO contains covalent double bonds whereas NaCl contains single ionic bonds.
B.Mg²⁺ and O²⁻ have higher ionic charges (+2/-2) and smaller interionic distances than Na⁺ and Cl⁻ (+1/-1).
C.Sodium has a larger electronegativity than magnesium, reducing its ionic bond strength.
D.NaCl forms a face-centered cubic structure whereas MgO forms a liquid crystal structure.
Explanation: Lattice energy by Coulomb's law is proportional to (q₁ · q₂) / r. MgO consists of divalent ions (+2 and -2, product = 4) with smaller ionic radii, while NaCl consists of monovalent ions (+1 and -1, product = 1). The fourfold charge product and smaller radius give MgO a vastly higher lattice energy (~3790 kJ/mol vs ~786 kJ/mol).

About the PAU Chemistry (Cantabria) Exam

Comprehensive 100-question practice test bank for the Cantabria (Universidad de Cantabria / UNICAN) PAU exam in Chemistry (Química). Chemistry is a core 2º Bachillerato subject under Real Decreto 243/2022 (LOMLOE), assessing atomic structure, thermodynamics, equilibrium, acid-base/redox, and organic chemistry as applied by UNICAN.

Exam sponsor: University of Cantabria (UNICAN) PAU Organising Commission. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

The Cantabria PAU exam in Chemistry (UNICAN) runs 90 minutes and is sat by Bachillerato Ciencias y Tecnología students during the Access Phase (or Admission Phase for grade improvement). It evaluates five core content blocks: atomic structure and bonding, thermochemistry, chemical equilibrium, acid-base and redox reactions, and organic chemistry.

Time Limit

90 minutes (1.5 hours)

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 71.09 base registration fee for PAU Access Phase (ordinary sitting, set by Universidad de Cantabria).

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.

20%

Atomic Structure, Periodicity & Chemical Bonding (Estructura Atómica y Enlace)

Quantum numbers, atomic orbitals, electron configurations, periodic trends (atomic radius, ionization energy, electron affinity, electronegativity), ionic, covalent, and metallic bonding, VSEPR molecular geometry, molecular polarity, hybridization, and intermolecular forces.

20%

Thermodynamics & Chemical Energetics (Termoquímica)

Enthalpy changes of reaction, formation, and combustion, Hess's Law, bond enthalpies, standard entropy changes, Gibbs free energy, and thermodynamic criteria for reaction spontaneity.

20%

Chemical Equilibrium & Solubility (Equilibrio Químico)

Reversible reactions, equilibrium constants (Kc, Kp), relation between Kc and Kp, reaction quotient Q, degree of dissociation, Le Chatelier's principle, heterogeneous equilibria, solubility product constant (Ksp), common ion effect, and precipitation.

20%

Acid-Base Equilibria & RedOx Reactions (Ácido-Base y RedOx)

Brønsted-Lowry acid-base theory, pH and pOH calculations, strong and weak acids/bases (Ka, Kb), salt hydrolysis, buffer solutions, acid-base titrations, oxidation numbers, balancing redox equations via ion-electron method, electrochemical cells (E°cell), Nernst equation, and Faraday's laws of electrolysis.

20%

Organic Chemistry: Nomenclature, Isomerism & Reactivity (Química Orgánica)

IUPAC nomenclature of hydrocarbons and functionalized organic compounds, structural and stereoisomerism (optical R/S and geometric E/Z), organic reaction mechanisms (addition, substitution, elimination, oxidation/reduction), Markovnikov and Zaitsev rules, and polymers.

Preparing for the PAU Chemistry (Cantabria) 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: The Cantabria PAU exam in Chemistry (UNICAN) runs 90 minutes and is sat by Bachillerato Ciencias y Tecnología students during the Access Phase (or Admission Phase for grade improvement). It evaluates five core content blocks: atomic structure and bonding, thermochemistry, chemical equilibrium, acid-base and redox reactions, and organic chemistry.
  • Time limit: 90 minutes (1.5 hours)
  • Exam / certification fees: EUR 71.09 base registration fee for PAU Access Phase (ordinary sitting, set by Universidad de Cantabria). 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

PAU Chemistry (Cantabria): Suggested Study Strategy

1Master step-by-step stoichiometric and equilibrium calculations, ensuring correct unit conversions (atm to Pa, K to °C, g to mol) and rounding to appropriate significant figures.
2Practice drawing Lewis structures, determining VSEPR geometries, and assigning molecular polarities for common inorganic species.
3Memorize the key thermochemical and electrochemical relations: ΔG° = ΔH° - TΔS° = -RT ln K = -nFE°cell.
4Develop speed in writing and balancing redox ion-electron half-reactions under both acidic and basic conditions.
5Learn IUPAC organic nomenclature rules systematically, including priority order of functional groups, R/S stereocenters, and major reaction mechanisms (addition, substitution, elimination).

Frequently Asked Questions

Is this practice bank in the same format as the real Cantabria PAU Chemistry exam?

No. The official Cantabria PAU paper for Chemistry is a 90-minute written examination sat in Spanish, consisting of four compulsory sections (apartados) worth 2.5 points each, featuring multi-part numerical problems, chemical reaction balancing, and theoretical justifications. This bank is an English-language multiple-choice study adaptation designed to drill core concepts, stoichiometric calculations, and mechanism rules efficiently.

What is the official syllabus for PAU Chemistry in Cantabria?

The syllabus is established by Real Decreto 243/2022 (LOMLOE) for 2º Bachillerato Chemistry, organized into five key blocks: atomic structure and bonding, thermochemistry, chemical equilibrium, acid-base and redox reactions, and organic chemistry.

How is the Cantabria PAU Chemistry exam scored for university admission?

The exam is graded on a 0 to 10 scale. When taken in the compulsory Access Phase, a minimum mark of 4.0 is required to calculate the PAU average (40% PAU + 60% Bachillerato GPA). When taken in the voluntary Admission Phase, scores above 5.0 can add up to 2 extra points toward specific degree admission cut-offs depending on weighting factors (0.1 or 0.2).

Are quantitative numerical calculations required on the Cantabria PAU Chemistry exam?

Yes. Numerical problems account for a major portion of the marks, including equilibrium constant determinations, enthalpy and free energy calculations, pH of weak acids/buffers, Faraday's electrolysis, and redox stoichiometry.

Can I use a scientific calculator during the Cantabria PAU Chemistry exam?

Yes, standard non-programmable, non-graphing scientific calculators without text-storage capability are permitted according to University of Cantabria PAU commission regulations.

In what language is the official Cantabria PAU examination administered?

Official PAU examinations at the University of Cantabria (UNICAN) are written and administered in Spanish.

When are the PAU sittings held in Cantabria for 2026?

The ordinary sitting takes place in early June (June 2–4, 2026), and the extraordinary sitting takes place in early July (June 30–July 2, 2026).