PracticeVideosBlogFlashcardsEspañol
All Practice Exams

Free Practice Questions for Castilla y León PAU Chemistry

Exam-style questions and explanations by OpenExamPrep.

✓ No registration✓ No credit card
Exam pass rate: High (~85-95% PAU overall pass rate in Castilla y León)
100+ Questions
100% Free

Loading practice questions...

Same family resources

Explore More Spain Castilla y León PAU (Prueba de Acceso a la Universidad)

Continue into nearby exams from the same family. Each card keeps practice questions, study guides, flashcards, videos, and articles in one place.

Castilla y León PAU Applied Mathematics for Social Sciences II

Practice Questions

Castilla y León PAU Artistic Drawing II

Practice Questions

Castilla y León PAU Artistic Foundations

Practice Questions

Castilla y León PAU Biology

Practice Questions

Castilla y León PAU Business and Business Model Design

Practice Questions

Castilla y León PAU Choir and Vocal Technique II

Practice Questions
Exam Review

Key Facts: Castilla y León PAU Chemistry Exam

90 min

Exam Time Limit

Junta de Castilla y León

0–10

Grading Scale

USAL / UVA / UBU / ULE

4.0

Min. Access Phase Score

Comisión PAU Castilla y León

EUR 76.82

Base Registration Fee

Junta de Castilla y León

5 Core Units

Curriculum Content Areas

2º Bachillerato Chemistry Syllabus

The Castilla y León PAU Chemistry exam (Química) is administered by public universities in Castilla y León (USAL, UVA, UBU, ULE) for students completing 2nd Bachillerato. The exam lasts 90 minutes and is graded on a 0–10 scale (minimum 4.0 required in the Access Phase). Note that local questions on this platform are an English-language MCQ study adaptation created to help students master the underlying 2nd Bachillerato curriculum.

Sample Castilla y León PAU Chemistry Practice Questions

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

1Which specific atomic orbital is characterized by the set of quantum numbers n = 3, l = 1, and ml = 0?
A.3s orbital
B.3p orbital
C.3d orbital
D.4p orbital
Explanation: The principal quantum number n = 3 specifies the third electron shell. The angular momentum quantum number l = 1 corresponds specifically to a p subshell. Therefore, n = 3 and l = 1 designate a 3p orbital.
2What is the ground-state electron configuration of a neutral iron atom (Fe, atomic number Z = 26)?
A.[Ar] 3d⁶ 4s²
B.[Ar] 3d⁸
C.[Ar] 3d⁵ 4s³
D.[Ar] 4s² 4p⁶
Explanation: Argon has 18 electrons. Iron has 26 electrons, meaning 8 valence electrons beyond the noble gas core. Following the Aufbau principle, the 4s orbital fills first with 2 electrons, and the remaining 6 electrons enter the 3d subshell, yielding [Ar] 3d⁶ 4s².
3How does the first ionization energy generally change across Period 3 of the periodic table from Sodium (Na) to Argon (Ar)?
A.It decreases continuously because atomic mass increases.
B.It increases generally due to increasing effective nuclear charge.
C.It remains constant because electrons are added to the same principal shell.
D.It fluctuates unpredictably with no observable trend.
Explanation: Across Period 3, protons are added to the nucleus, increasing the nuclear charge while core shielding remains relatively constant. This increases the effective nuclear charge (Zeff), pulling valence electrons more tightly and requiring more energy to remove an electron.
4Which of the following statements correctly compares the atomic/ionic radii of Na vs Na⁺ and Cl vs Cl⁻?
A.Na⁺ is larger than Na, and Cl⁻ is smaller than Cl.
B.Na⁺ is smaller than Na, and Cl⁻ is larger than Cl.
C.Both Na⁺ and Cl⁻ are larger than their neutral parent atoms.
D.Both Na⁺ and Cl⁻ are smaller than their neutral parent atoms.
Explanation: Cations are smaller than their parent neutral atoms because removing electrons decreases electron-electron repulsion and often removes an entire outer shell (Na → Na⁺). Anions are larger than their parent atoms because adding electrons increases electron-electron repulsion, expanding the electron cloud (Cl → Cl⁻).
5According to Hund's rule of maximum multiplicity, how do electrons populate degenerate 2p orbitals in a ground-state carbon atom (Z = 6)?
A.They pair up in a single 2p orbital with antiparallel spins.
B.They occupy two separate 2p orbitals with parallel spins.
C.They occupy two separate 2p orbitals with antiparallel spins.
D.They enter the 3s orbital before filling the 2p subshell.
Explanation: Hund's rule states that when electrons enter degenerate orbitals (orbitals of equal energy), one electron enters each orbital until all degenerate orbitals are singly occupied, and all singly occupied electrons have parallel spins to minimize electron repulsion.
6Which of the following sets of quantum numbers (n, l, ml, ms) is physically impossible for an electron in an atom?
A.n = 3, l = 2, ml = -1, ms = +1/2
B.n = 2, l = 2, ml = 0, ms = -1/2
C.n = 4, l = 0, ml = 0, ms = +1/2
D.n = 1, l = 0, ml = 0, ms = -1/2
Explanation: The angular momentum quantum number l can only take integer values from 0 up to n - 1. For n = 2, the maximum allowed value of l is 1 (2s or 2p). A value of l = 2 would require n ≥ 3 (d subshell).
7What is the ground-state electron configuration of the ferric cation Fe³⁺ (atomic number Z = 26)?
A.[Ar] 3d⁵
B.[Ar] 3d³ 4s²
C.[Ar] 3d⁶
D.[Ar] 3d⁴ 4s¹
Explanation: Neutral Fe is [Ar] 3d⁶ 4s². When transition metals ionize, electrons are removed first from the outermost principal shell (4s) before removing electrons from 3d. Removing 3 electrons takes 2 from 4s and 1 from 3d, leaving [Ar] 3d⁵.
8Which element on the Pauling scale has the highest electronegativity value (3.98)?
A.Oxygen (O)
B.Chlorine (Cl)
C.Fluorine (F)
D.Helium (He)
Explanation: Fluorine is the most electronegative element in the periodic table (assigned ~4.0 on the Pauling scale) due to its small atomic radius and high effective nuclear charge.
9Arranging the isoelectronic species O²⁻, F⁻, Na⁺, and Mg²⁺ in order of decreasing ionic radius yields which sequence?
A.O²⁻ > F⁻ > Na⁺ > Mg²⁺
B.Mg²⁺ > Na⁺ > F⁻ > O²⁻
C.F⁻ > O²⁻ > Mg²⁺ > Na⁺
D.Na⁺ > Mg²⁺ > O²⁻ > F⁻
Explanation: All four species are isoelectronic with 10 electrons (configuration 1s² 2s² 2p⁶). In an isoelectronic series, ionic radius decreases as nuclear charge (atomic number Z) increases. O²⁻ (Z=8) has the smallest Z and largest radius, while Mg²⁺ (Z=12) has the largest Z and smallest radius.
10What is effective nuclear charge (Zeff), and how does core electron shielding affect it?
A.Zeff is the total charge of all neutrons; shielding increases it.
B.Zeff is the net positive charge felt by a valence electron, reduced by core electron shielding (Zeff = Z - S).
C.Zeff is equal to the atomic mass number minus the number of valence electrons.
D.Zeff is the negative charge exerted by outer shell electrons on the nucleus.
Explanation: Effective nuclear charge (Zeff) represents the net positive attractive force experienced by valence electrons from the nucleus. Core electrons shield valence electrons from the full nuclear charge Z, giving Zeff = Z - S, where S is the shielding constant.

About the Castilla y León PAU Chemistry Exam

The Castilla y León PAU Chemistry exam (Química 2º Bachillerato) evaluates secondary school graduates across Castilla y León on core chemical principles including atomic structure, chemical bonding, thermodynamics, kinetics, chemical and acid-base equilibrium, electrochemistry, and organic chemistry. Please note: The official PAU exam features written numerical and theoretical questions in Spanish; the 100 questions provided here are an English-language multiple-choice study adaptation designed for self-assessment and core concept mastery.

Exam sponsor: Universidades de Castilla y León (USAL, UVA, UBU, ULE) / Consejería de Educación de la Junta de Castilla y León. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

90-minute written examination (traditionally open-ended numerical and conceptual problems; local questions are an English-language MCQ study adaptation)

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 76.82 base registration fee for PAU Access Phase (plus EUR 10.33 per voluntary subject) set by Junta de Castilla y León.

Exam sponsor website

Reported exam pass rate: High (~85-95% PAU overall pass rate in Castilla y León). This describes exam candidates, not OpenExamPrep users or results from using our resources. 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 and Periodic Properties

Bohr model, quantum numbers (n, l, ml, ms), atomic orbital shapes, electron configurations, Aufbau principle, Pauli exclusion principle, Hund's rule, periodic properties (atomic and ionic radii, first ionization energy, electron affinity, electronegativity), and periodic trends across periods and groups.

20%

Chemical Bonding and Molecular Structure

Ionic bond formation, lattice energy, Born-Haber thermochemical cycles, covalent bonding, Lewis electron dot structures, formal charges, resonance, VSEPR molecular geometry, valence bond theory, hybrid orbitals (sp, sp2, sp3), bond polarity and dipole moments, metallic bonding, and intermolecular forces (hydrogen bonding, dipole-dipole, London dispersion).

20%

Chemical Thermodynamics and Kinetics

State functions, first law of thermodynamics, reaction enthalpy (ΔH), standard enthalpies of formation and combustion, Hess's Law, bond dissociation energies, second law, standard entropy (ΔS), Gibbs free energy equation (ΔG = ΔH - TΔS), reaction spontaneity criteria, reaction rate definitions, rate laws, reaction order, activation energy (Ea), Arrhenius equation, and catalysis.

25%

Chemical Equilibria: Acid-Base and Solubility

Reversible reactions, dynamic equilibrium, equilibrium constants (Kc, Kp) and their relation (Kp = Kc(RT)^Δn), degree of dissociation (α), Le Chatelier's principle, Brønsted-Lowry acid-base theory, pH and pOH scale, water autoionization (Kw), weak acid/base constants (Ka, Kb), salt hydrolysis, buffer solutions (Henderson-Hasselbalch equation), volumetric titrations, and solubility product constant (Ks) with common ion effect.

15%

Electrochemistry and Organic Chemistry

Oxidation state determination, balancing redox equations using the ion-electron method in acidic and basic media, galvanic cells, standard reduction potentials (E°), cell electromotive force (EMF), Nernst equation, electrolytic cells, Faraday's laws of electrolysis, IUPAC organic nomenclature, structural and stereoisomerism, and main organic reaction types (substitution, addition, elimination, oxidation-reduction, esterification).

Preparing for the Castilla y León 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 >= 5.0 to pass).
  • Assessment: 90-minute written examination (traditionally open-ended numerical and conceptual problems; local questions are an English-language MCQ study adaptation)
  • Time limit: 90 minutes (1.5 hours)
  • Exam / certification fees: EUR 76.82 base registration fee for PAU Access Phase (plus EUR 10.33 per voluntary subject) set by Junta de Castilla y León. 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

Castilla y León PAU Chemistry: Suggested Study Strategy

1Practice balancing redox equations using the ion-electron method in both acidic and basic solutions until seamless.
2Master equilibrium expressions: solve Kc and Kp calculations, degree of dissociation (α), and solubility product (Ks) problems.
3Understand acid-base behavior: learn to derive pH for weak acids/bases, salt hydrolysis reactions, and buffer systems.
4Apply Hess's Law and free energy equations (ΔG = ΔH - TΔS) to determine thermodynamic spontaneity under standard and non-standard conditions.
5Memorize IUPAC organic nomenclature rules and practice predicting major products for addition, substitution, elimination, and esterification reactions.

Frequently Asked Questions

What is the format of the official Castilla y León PAU Chemistry exam?

The official Castilla y León PAU Chemistry exam is a 90-minute written examination administered in Spanish, consisting of numerical calculation problems and theoretical questions. Note that the 100 questions available on this site are an English-language multiple-choice practice adaptation developed to help students test their knowledge of the official curriculum.

What is the passing score for Castilla y León 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 Castilla y León?

The base registration fee for the PAU Access Phase in Castilla y León is set by the Junta de Castilla y León at EUR 76.82 (plus EUR 10.33 per subject in the voluntary admission phase), with fee exemptions for large families and specific categories.

Who sets the curriculum for the Castilla y León PAU Chemistry test?

The curriculum and exam criteria are established by the Commission of Public Universities of Castilla y León (USAL, UVA, UBU, ULE) in coordination with the Consejería de Educación de la Junta de Castilla y León based on the 2nd Bachillerato official chemistry syllabus.

Why are the practice questions here in English and in multiple-choice format?

These questions serve as an English-language MCQ study adaptation designed for international students, bilingual program candidates, and revision learners seeking to test core chemistry concepts tested on the Castilla y León curriculum.