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Key Facts: Extremadura PAU Chemistry Exam

EUR 78.26

Ordinary registration fee for PAU

Universidad de Extremadura (UEx)

90 Mins

Official examination duration

Comisión Organizadora de la PAU de Extremadura

Min 4.0

Minimum Access Phase score required to combine with Bachillerato GPA

UEx / Junta de Extremadura

7 Topics

Core chemistry syllabus units

2º Bachillerato LOMLOE Chemistry Curriculum

100

Practice questions available in this OpenExamPrep bank

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Master Extremadura PAU Chemistry with 100 realistic practice questions and complete numerical step-by-step solutions.

Sample Extremadura PAU Chemistry Practice Questions

Try these sample questions to review concepts for the Extremadura 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) is valid for the highest-energy valence electron of a ground-state chlorine atom (Z = 17)?
A.(2, 1, -1, +1/2)
B.(3, 2, 0, -1/2)
C.(3, 0, +1, +1/2)
D.(3, 1, 0, +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 n = 3 and l = 1. For l = 1, ml can be -1, 0, or +1, and ms can be +1/2 or -1/2. Thus, (3, 1, 0, +1/2) is a valid set.
2What is the 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] 4s¹ 3d⁶
Explanation: Chromium (Z = 24) is an exception to the standard Aufbau ordering due to the stability associated with a half-filled 3d subshell. Promoting one electron from 4s to 3d gives [Ar] 3d⁵ 4s¹.
3Which of the following general trends correctly describes the first ionization energy across Period 3 elements from sodium to argon?
A.It decreases systematically because atomic radius increases.
B.It remains constant because electrons fill the same principal quantum shell (n = 3).
C.It increases overall due to increasing effective nuclear charge Z*.
D.It reaches a minimum at argon due to electron shielding.
Explanation: Across Period 3 from Na to Ar, nuclear charge Z increases while core shielding remains relatively constant. This increases effective nuclear charge Z*, pulling valence electrons closer and requiring more energy to remove an electron.
4Calculate 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 = 6.63 × 10⁻³⁴ J·s).
A.0.364 nm
B.1.21 nm
C.3.64 nm
D.0.036 nm
Explanation: According to the de Broglie relation, λ = h / (m · v). Substituting values: 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.
5A metal surface has a work function (threshold energy) W₀ = 4.41 × 10⁻¹⁹ J. What is the threshold frequency f₀ required to emit photoelectrons? (h = 6.63 × 10⁻³⁴ J·s).
A.4.41 × 10¹⁴ Hz
B.6.65 × 10¹⁴ Hz
C.1.50 × 10¹⁵ Hz
D.2.92 × 10⁻¹⁵ Hz
Explanation: The photoelectric effect equation gives W₀ = h · f₀. Rearranging for frequency: f₀ = W₀ / h = (4.41 × 10⁻¹⁹ J) / (6.63 × 10⁻³⁴ J·s) = 6.65 × 10¹⁴ Hz.
6Calculate the energy of a photon emitted when an electron in a hydrogen atom undergoes a transition from the n = 4 level to the n = 2 level. (Rydberg constant / energy level formula Eₙ = -2.18 × 10⁻¹⁸ J / n²).
A.1.36 × 10⁻¹⁹ J
B.5.45 × 10⁻¹⁹ J
C.4.09 × 10⁻¹⁹ J
D.2.18 × 10⁻¹⁸ J
Explanation: E₄ = -2.18 × 10⁻¹⁸ / 4² = -1.3625 × 10⁻¹⁹ J. E₂ = -2.18 × 10⁻¹⁸ / 2² = -5.45 × 10⁻¹⁹ J. ΔE = E₄ - E₂ = (-1.3625 × 10⁻¹⁹) - (-5.45 × 10⁻¹⁹) = +4.0875 × 10⁻¹⁹ J ≈ 4.09 × 10⁻¹⁹ J.
7Which set of isoelectronic species is correctly arranged in order of INCREASING ionic radius?
A.Ca²⁺ < K⁺ < Cl⁻ < S²⁻
B.S²⁻ < Cl⁻ < K⁺ < Ca²⁺
C.K⁺ < Ca²⁺ < S²⁻ < Cl⁻
D.Cl⁻ < S²⁻ < Ca²⁺ < K⁺
Explanation: All four species (Ca²⁺, K⁺, Cl⁻, S²⁻) have 18 electrons (isoelectronic with Ar). As nuclear charge Z increases (Ca=20, K=19, Cl=17, S=16), the electrostatic pull on the 18 electrons increases, making ionic radius smaller. Thus Ca²⁺ (smallest) < K⁺ < Cl⁻ < S²⁻ (largest).
8Why is the second ionization energy of sodium (IE₂ = 4562 kJ/mol) drastically higher than its first ionization energy (IE₁ = 496 kJ/mol)?
A.Sodium forms a covalent network after losing its first electron.
B.The second ionization requires breaking a noble gas core octet of neon by adding an electron.
C.Sodium has a higher electron affinity for cationic states.
D.The second electron is removed from a stable, filled 2p core subshell closer to the nucleus.
Explanation: Neutral Na ([Ne] 3s¹) loses its 3s electron easily to form Na⁺ ([Ne]). Removing a second electron requires pulling an electron from the stable 2p⁶ inner core subshell (n = 2), which experiences a much higher effective nuclear charge Z* and is closer to the nucleus.
9What is the wavelength of the photon emitted in the Lyman series transition from n = 3 to n = 1 in a hydrogen atom? (ΔE = 1.938 × 10⁻¹⁸ J, h = 6.63 × 10⁻³⁴ J·s, c = 3.00 × 10⁸ m/s).
A.103 nm
B.656 nm
C.486 nm
D.121 nm
Explanation: λ = h · c / ΔE = (6.63 × 10⁻³⁴ J·s × 3.00 × 10⁸ m/s) / (1.938 × 10⁻¹⁸ J) = (1.989 × 10⁻²⁵) / (1.938 × 10⁻¹⁸) = 1.026 × 10⁻⁷ m = 103 nm (ultraviolet Lyman line).
10What is the ground-state electron configuration of the iron(III) ion, Fe³⁺ (Z = 26)?
A.[Ar] 4s² 3d³
B.[Ar] 3d⁵
C.[Ar] 4s¹ 3d⁴
D.[Ar] 3d⁶
Explanation: Neutral Fe (Z = 26) has configuration [Ar] 4s² 3d⁶. Transition metals lose valence 4s electrons first during ionization. Removing 3 electrons (two from 4s and one from 3d) yields [Ar] 3d⁵.

About the Extremadura PAU Chemistry Exam

The Extremadura PAU Chemistry (Química 2º Bachillerato) practice question bank covers all core competencies evaluated by Universidad de Extremadura (UEx). Designed to prepare students for the 90-minute university entrance exam, it includes numerical stoichiometry, atomic structure, thermochemistry, chemical equilibrium, acid-base pH calculations, electrochemistry, and organic reaction mechanisms.

Exam sponsor: Comisión Organizadora de la PAU de Extremadura (Universidad de Extremadura - UEx / Consejería de Educación de la Junta de Extremadura). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

90-minute written examination (numerical problem solving, chemical reactions, theory questions; 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 78.26 ordinary registration fee for PAU (50% discount EUR 39.13 for general large family; 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.

15%

Atomic Structure & Periodic Table

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

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

Enthalpy of reaction (Hess's law, standard formation enthalpies), entropy, Gibbs free energy, and reaction spontaneity.

15%

Chemical Equilibrium & Solubilities

Homogeneous and heterogeneous equilibria (Kc, Kp), Le Chatelier's principle, degree of dissociation, solubility product (Ksp), and common ion effect.

15%

Acid-Base Reactions

Brønsted-Lowry & Lewis definitions, pH/pOH calculations for strong and weak acids/bases, salt hydrolysis, buffer solutions, and volumetric titrations.

15%

Redox & Electrochemistry

Oxidation numbers, balancing redox equations (ion-electron method), galvanic cells, standard reduction potentials (E°), Nernst equation, and Faraday's laws of electrolysis.

10%

Organic Chemistry

IUPAC nomenclature, isomerism (structural, geometric/cis-trans, optical/stereoisomerism), reaction types (addition, substitution, elimination, oxidation/reduction, esterification), and polymers.

Preparing for the Extremadura 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 (numerical problem solving, chemical reactions, theory questions; local questions are an English-language MCQ study adaptation)
  • Time limit: 90 minutes (1.5 hours)
  • Exam / certification fees: EUR 78.26 ordinary registration fee for PAU (50% discount EUR 39.13 for general large family; 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

Extremadura PAU Chemistry: Suggested Study Strategy

1Master step-by-step stoichiometric calculations and pay close attention to significant figures and standard units.
2Practice thermochemical calculations using Hess's Law and Gibbs free energy equation (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 both acidic and basic media alongside Faraday's laws.

Frequently Asked Questions

What is the registration fee for the PAU exam in Extremadura?

EUR 78.26 ordinary registration fee for PAU (50% discount EUR 39.13 for general large family; full exemption for special large family, disability, or terrorism victims).

What passing score is required on the PAU Chemistry exam in Extremadura?

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).

What is the duration and format of the PAU Chemistry exam in Extremadura?

90-minute written examination (numerical problem solving, chemical reactions, theory questions; local questions are an English-language MCQ study adaptation)

Which body organizes the PAU exam in Extremadura?

Comisión Organizadora de la PAU de Extremadura (Universidad de Extremadura - UEx / Consejería de Educación de la Junta de Extremadura)