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Free Practice Questions for Galicia PAU Chemistry / Química 2º Bachillerato CIUG

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Key Facts: Galicia PAU Chemistry / Química 2º Bachillerato CIUG Exam

90 min

Exam duration (1.5 hours)

CIUG PAU Guidelines

0–10

Grading scale

CIUG Evaluation Criteria

4.0

Minimum Access Phase mark required

Spanish University Access Regulations

63.67 €

Ordinary registration fee

CIUG Official Fees

100

Practice questions in this OpenExamPrep bank

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Galicia PAU Chemistry (CIUG 2026) is a 90-minute examination assessing 2º Bachillerato chemistry competencies across 5 key domain areas under LOMLOE guidelines.

Sample Galicia PAU Chemistry / Química 2º Bachillerato CIUG Practice Questions

Try these sample questions to review concepts for the Galicia PAU Chemistry / Química 2º Bachillerato CIUG 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 allowed for a valence electron in a ground-state sulfur atom (Z = 16)?
A.n = 3, l = 1, ml = -1, ms = -1/2
B.n = 3, l = 2, ml = 0, ms = +1/2
C.n = 2, l = 1, ml = +1, ms = -1/2
D.n = 3, l = 1, ml = +2, ms = +1/2
Explanation: Sulfur (Z = 16) has the ground-state electron configuration 1s² 2s² 2p⁶ 3s² 3p⁴. The valence electrons occupy the n = 3 shell. For 3p electrons, n = 3 and l = 1. Permissible values for ml range from -l to +l (-1, 0, +1), and ms can be +1/2 or -1/2. Therefore, n = 3, l = 1, ml = -1, ms = -1/2 is a valid set.
2What is the ground-state electron configuration of the iron(III) ion, Fe³⁺ (Z = 26)?
A.[Ar] 3d⁵
B.[Ar] 4s² 3d³
C.[Ar] 4s¹ 3d⁴
D.[Ar] 3d⁶
Explanation: Neutral iron (Z = 26) has the electron configuration [Ar] 4s² 3d⁶. When transition metals ionize, electrons are removed first from the outermost 4s subshell, then from the 3d subshell. Removing three electrons yields Fe³⁺ with configuration [Ar] 3d⁵, representing a stable half-filled d subshell.
3Why is the first ionization energy of phosphorus (Z = 15) higher than that of sulfur (Z = 16)?
A.Phosphorus has a stable half-filled 3p³ subshell, whereas sulfur has paired electrons in one 3p orbital experiencing electron-electron repulsion.
B.Sulfur has a smaller nuclear charge than phosphorus, resulting in weaker attraction for valence electrons.
C.Phosphorus has a significantly smaller atomic radius than sulfur.
D.Sulfur's valence electrons are shielded by an extra inner electron shell.
Explanation: Phosphorus ([Ar] 3s² 3p³) has three unpaired electrons in three degenerate 3p orbitals, giving an extra exchange energy stability due to a half-filled subshell. Sulfur ([Ar] 3s² 3p⁴) has two paired electrons in one 3p orbital. The interelectronic repulsion between these paired electrons lowers the energy required to remove one electron from sulfur.
4Which list arranges the isoelectronic species N³⁻, O²⁻, F⁻, Na⁺, Mg²⁺ in order of DECREASING ionic radius?
A.N³⁻ > O²⁻ > F⁻ > Na⁺ > Mg²⁺
B.Mg²⁺ > Na⁺ > F⁻ > O²⁻ > N³⁻
C.F⁻ > O²⁻ > N³⁻ > Mg²⁺ > Na⁺
D.N³⁻ > F⁻ > O²⁻ > Na⁺ > Mg²⁺
Explanation: All five species are isoelectronic with 10 electrons (configuration 1s² 2s² 2p⁶). The ionic radius in an isoelectronic series is determined by nuclear charge (Z). As Z increases from N (Z=7) to Mg (Z=12), the greater nuclear pull contracts the electron cloud. Thus, N³⁻ (Z=7) is largest and Mg²⁺ (Z=12) is smallest.
5Given standard enthalpies for NaCl formation: Sublimation of Na(s) = +107 kJ/mol, 1st Ionization Energy of Na(g) = +496 kJ/mol, Bond dissociation of Cl₂(g) = +244 kJ/mol, Electron affinity of Cl(g) = -349 kJ/mol, and Standard enthalpy of formation ΔH°f(NaCl, s) = -411 kJ/mol. Calculate the lattice enthalpy (ΔH_lattice) for NaCl(s) → Na⁺(g) + Cl⁻(g).
A.+787 kJ/mol
B.+665 kJ/mol
C.+388 kJ/mol
D.+909 kJ/mol
Explanation: According to Hess's Law applied to the Born-Haber cycle: ΔH°f = ΔH_sub(Na) + IE₁(Na) + 1/2 ΔH_diss(Cl₂) + EA₁(Cl) - ΔH_lattice -411 = +107 + 496 + 1/2(244) + (-349) - ΔH_lattice -411 = 107 + 496 + 122 - 349 - ΔH_lattice = +376 - ΔH_lattice ΔH_lattice = +376 - (-411) = +787 kJ/mol.
6In the preferred Lewis structure of the sulfate ion, SO₄²⁻, with expanded octet to minimize formal charges, what are the formal charges on the sulfur atom and the double-bonded oxygen atoms?
A.Formal charge on S = 0; formal charge on double-bonded O = 0
B.Formal charge on S = +2; formal charge on double-bonded O = -1
C.Formal charge on S = +1; formal charge on double-bonded O = 0
D.Formal charge on S = 0; formal charge on double-bonded O = -1
Explanation: In SO₄²⁻, sulfur has 6 valence electrons. In the structure with two S=O double bonds and two S-O⁻ single bonds, sulfur forms 6 covalent bonds (12 shared electrons) and has no lone pairs: FC(S) = 6 - 0 - 6 = 0. The double-bonded oxygens have 2 lone pairs and 2 bonds: FC(O=) = 6 - 4 - 2 = 0. The single-bonded oxygens have 3 lone pairs and 1 bond: FC(O⁻) = 6 - 6 - 1 = -1.
7According to VSEPR theory, what are the electron domain geometry and molecular geometry of sulfur tetrafluoride, SF₄?
A.Trigonal bipyramidal electron domain geometry; seesaw molecular geometry
B.Tetrahedral electron domain geometry; tetrahedral molecular geometry
C.Square planar electron domain geometry; square planar molecular geometry
D.Octahedral electron domain geometry; square pyramidal molecular geometry
Explanation: Sulfur in SF₄ has 6 valence electrons + 4 single bonds = 10 electrons around S (5 electron pairs: 4 bonding pairs and 1 lone pair). 5 electron domains adopt a trigonal bipyramidal domain geometry. To minimize lone pair-bonding pair repulsions, the lone pair occupies an equatorial position, giving a seesaw molecular shape.
8What are the hybridizations of the carbon atoms in ethyne (acetylene, C₂H₂), ethene (ethylene, C₂H₄), and ethane (C₂H₆), respectively?
A.C₂H₂: sp; C₂H₄: sp²; C₂H₆: sp³
B.C₂H₂: sp²; C₂H₄: sp³; C₂H₆: sp
C.C₂H₂: sp³; C₂H₄: sp²; C₂H₆: sp
D.C₂H₂: sp; C₂H₄: sp³; C₂H₆: sp²
Explanation: In ethyne (H-C≡C-H), each carbon forms 2 σ-bonds (linear shape, 180° bond angle) requiring sp hybridization. In ethene (H₂C=CH₂), each carbon forms 3 σ-bonds (trigonal planar shape, 120° bond angle) requiring sp² hybridization. In ethane (H₃C-CH₃), each carbon forms 4 σ-bonds (tetrahedral shape, 109.5° bond angle) requiring sp³ hybridization.
9Which of the following molecules has a non-zero net dipole moment (is polar)?
A.Sulfur dioxide, SO₂
B.Carbon dioxide, CO₂
C.Boron trifluoride, BF₃
D.Carbon tetrachloride, CCl₄
Explanation: SO₂ has a bent molecular shape due to 1 lone pair and 2 bonding domains on sulfur (VSEPR angle ~119°). The S-O bond dipoles do not cancel out, resulting in a net dipole moment μ > 0. CO₂ (linear), BF₃ (trigonal planar), and CCl₄ (tetrahedral) are highly symmetric, causing their bond dipoles to cancel out completely (μ = 0).
10Which of the following compounds has the highest boiling point, and what is the primary intermolecular force responsible?
A.Ethanol (CH₃CH₂OH); hydrogen bonding
B.Dimethyl ether (CH₃OCH₃); dipole-dipole interactions
C.Ethane (CH₃CH₃); London dispersion forces
D.Fluoromethane (CH₃F); ion-dipole interactions
Explanation: Ethanol contains an -OH group where hydrogen is covalently bonded to highly electronegative oxygen, allowing strong intermolecular hydrogen bonding. Dimethyl ether (polar, dipole-dipole) and ethane (nonpolar, London dispersion) lack hydrogen bond donors, giving ethanol a significantly higher boiling point (78 °C vs -24 °C for dimethyl ether).

About the Galicia PAU Chemistry / Química 2º Bachillerato CIUG Exam

The Galicia PAU Chemistry examination (Química CIUG) evaluates university applicants on 2º Bachillerato LOMLOE Chemistry syllabus. Main areas assessed include quantum structure, chemical bonding, thermochemistry, reaction kinetics, chemical equilibrium, acid-base chemistry, electrochemistry, and organic reaction mechanisms.

Exam sponsor: Comisión Interuniversitaria de Galicia (CIUG). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

The PAU Chemistry examination administered by the Comisión Interuniversitaria de Galicia (CIUG) consists of written chemical problems and theoretical questions lasting 90 minutes. Students complete mandatory and elective tasks covering the 2º Bachillerato Chemistry curriculum under LOMLOE. Practice items in this bank adapt CIUG open and semi-constructed tasks into a standardized 100-question multiple-choice review.

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 >= 5.0 to pass).

Exam / Certification Fees

EUR 63.67 ordinary registration fee for PAU (50% discount EUR 31.84 for general large family status; full exemption for special large family, disability, or terrorism victims).

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 & Chemical Bonding

Quantum numbers, electronic configurations, periodic trends (ionization energy, electronegativity, atomic radius), ionic and covalent bonding models, Lewis structures, VSEPR geometry, orbital hybridization, and intermolecular forces.

20%

Thermodynamics & Chemical Kinetics

Thermochemistry, enthalpy of reaction, Hess's law, bond enthalpies, entropy, Gibbs free energy spontaneity, reaction rates, rate laws, order of reaction, half-life, and Arrhenius activation energy.

20%

Chemical Equilibrium & Le Chatelier

Equilibrium constants (Kc and Kp), degree of dissociation, reaction quotient (Qc), Le Chatelier's principle, heterogeneous equilibria, and solubility product constant (Ksp) with common ion effect.

20%

Acid-Base Equilibria & pH Calculations

Arrhenius and Brønsted-Lowry acid-base concepts, pH and pOH, weak acid/base ionization constants (Ka, Kb), salt hydrolysis, buffer solution pH (Henderson-Hasselbalch), and acid-base titration curves/indicators.

20%

Redox Reactions, Electrochemistry & Organic Chemistry

Oxidation states, ion-electron method for balancing redox equations, galvanic cells, standard reduction potentials, Nernst equation, Faraday's electrolysis laws, IUPAC organic nomenclature, isomerism, and organic reaction mechanisms.

Preparing for the Galicia PAU Chemistry / Química 2º Bachillerato CIUG 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 >= 5.0 to pass).
  • Assessment: The PAU Chemistry examination administered by the Comisión Interuniversitaria de Galicia (CIUG) consists of written chemical problems and theoretical questions lasting 90 minutes. Students complete mandatory and elective tasks covering the 2º Bachillerato Chemistry curriculum under LOMLOE. Practice items in this bank adapt CIUG open and semi-constructed tasks into a standardized 100-question multiple-choice review.
  • Time limit: 90 minutes (1.5 hours)
  • Exam / certification fees: EUR 63.67 ordinary registration fee for PAU (50% discount EUR 31.84 for general large family status; full exemption for special large family, disability, or terrorism victims). 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

Galicia PAU Chemistry / Química 2º Bachillerato CIUG: Suggested Study Strategy

1Master multi-step stoichiometric and thermochemical calculations using Hess's Law and standard enthalpies of formation.
2Practice solving ICE tables for chemical equilibrium constants (Kc, Kp) and weak acid-base dissociation systems.
3Be confident in balancing redox reactions in both acidic and basic media using the ion-electron method.
4Memorize standard IUPAC organic nomenclature rules and practice identifying functional groups, isomerism, and reaction mechanisms.
5Review VSEPR theory and hybridization to quickly determine molecular geometries, bond angles, and polarity.

Frequently Asked Questions

What is the Galicia PAU Chemistry exam?

It is the university entrance exam for Chemistry (Química) in Galicia, organized by the Comisión Interuniversitaria de Galicia (CIUG) for 2º Bachillerato Science track students.

What is the format and duration of the official CIUG exam?

The official exam lasts 90 minutes and consists of written chemical calculations, multi-part numerical problems, chemical reaction equations, and theoretical concept questions.

How is the final PAU grade calculated for university admission?

The PAU exam is graded from 0 to 10 points. Students must achieve at least 4.0 in the Access Phase so that 40% of the PAU score combines with 60% of the Bachillerato GPA to reach a minimum passing total of 5.0.

In which languages can the CIUG exam be taken?

Students in Galicia can request the official exam paper in Galician (gl) or Spanish (es).