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Free Practice Questions for Angola 12th Grade Chemistry National Exam

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Key Facts: Angola 12th Grade Chemistry National Exam Exam

88

English-language MCQ study adaptations in this bank

OpenExamPrep reviewed bank

15 top-level items

Top-level structure of the published 2026 official paper

INADE published paper

120 + 30

Official minutes plus tolerance

Decreto Executivo 81/26

0–200 → 0–20

Official scoring conversion

Decreto Executivo 81/26

Official paper: 15 top-level items, 120 minutes plus 30 minutes tolerance, scored 0–200 and converted to 0–20. Practice bank: 88 English-language MCQ study adaptations covering topics from the published scope, not an official format simulation.

Sample Angola 12th Grade Chemistry National Exam Practice Questions

Try these sample questions to review concepts for the Angola 12th Grade Chemistry National Exam exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 88+ question experience with AI tutoring.

1How many protons, neutrons, and electrons are present in a neutral atom of phosphorus-31 (atomic number Z = 15, mass number A = 31)?
A.15 protons, 16 neutrons, 15 electrons
B.15 protons, 31 neutrons, 15 electrons
C.16 protons, 15 neutrons, 16 electrons
D.15 protons, 16 neutrons, 16 electrons
Explanation: The atomic number (Z = 15) defines the number of protons in the nucleus, which equals 15. In a neutral atom, the number of electrons equals the number of protons (15 electrons). The number of neutrons is found by subtracting the atomic number from the mass number (A - Z = 31 - 15 = 16 neutrons).
2Which of the following represents a valid set of quantum numbers (n, l, ml, ms) for an electron in a 3d subshell?
A.n = 3, l = 2, ml = -1, ms = +1/2
B.n = 3, l = 3, ml = 0, ms = -1/2
C.n = 3, l = 1, ml = +2, ms = +1/2
D.n = 2, l = 2, ml = -2, ms = -1/2
Explanation: For a 3d subshell, the principal quantum number is n = 3 and the azimuthal (angular momentum) quantum number is l = 2 (where s=0, p=1, d=2). The magnetic quantum number ml can take any integer value from -l to +l (i.e., -2, -1, 0, +1, +2), and the spin quantum number ms must be +1/2 or -1/2. Thus, (3, 2, -1, +1/2) is valid.
3What is the correct ground-state electron configuration of a neutral chromium atom (Cr, Z = 24)?
A.[Ar] 4s1 3d5
B.[Ar] 4s2 3d4
C.[Ar] 3d6
D.[Ar] 4s2 4p4
Explanation: Chromium (Z = 24) exhibits an anomalous ground-state electron configuration due to the enhanced quantum mechanical exchange energy associated with a half-filled 3d subshell. An electron from the 4s orbital is promoted to the 3d subshell, yielding the stable configuration [Ar] 4s1 3d5 rather than [Ar] 4s2 3d4.
4Why is the first ionization energy of nitrogen (N, Z = 7) higher than that of oxygen (O, Z = 8), despite oxygen having a higher nuclear charge?
A.Oxygen has a paired electron in one of its 2p orbitals, resulting in increased electron-electron repulsion that makes it easier to remove
B.Nitrogen has a smaller atomic radius than oxygen, holding its outer electrons more tightly
C.Oxygen's outer electrons experience significantly greater shielding from inner core electrons
D.Nitrogen has a completely filled 2p subshell, giving it noble gas stability
Explanation: Nitrogen has the configuration 1s2 2s2 2px1 2py1 2pz1 with a half-filled 2p subshell where each 2p orbital contains one unpaired electron. Oxygen has the configuration 1s2 2s2 2px2 2py1 2pz1; the pairing of two electrons in the 2px orbital creates mutual electrostatic repulsion, making the removal of one 2p electron from oxygen thermodynamically easier than from nitrogen.
5Which of the following correctly arranges the isoelectronic species S2-, Cl-, K+, and Ca2+ in order of decreasing ionic radius (largest to smallest)?
A.S2- > Cl- > K+ > Ca2+
B.Ca2+ > K+ > Cl- > S2-
C.K+ > Ca2+ > S2- > Cl-
D.Cl- > S2- > Ca2+ > K+
Explanation: All four species possess 18 electrons (isoelectronic with argon). As the nuclear charge (number of protons) increases from S (16) to Cl (17) to K (19) to Ca (20), the greater positive nuclear charge exerts a stronger electrostatic pull on the identical electron cloud, drawing it closer to the nucleus. Therefore, S2- (16 protons) is the largest and Ca2+ (20 protons) is the smallest.
6An unknown Period 3 element X exhibits the following successive ionization energies: IE1 = 738 kJ/mol, IE2 = 1451 kJ/mol, IE3 = 7733 kJ/mol, IE4 = 10543 kJ/mol. In which group of the Periodic Table is element X located?
A.Group 2 (Alkaline earth metals)
B.Group 1 (Alkali metals)
C.Group 13 (Boron group)
D.Group 14 (Carbon group)
Explanation: There is a massive jump in ionization energy between IE2 (1451 kJ/mol) and IE3 (7733 kJ/mol), which is more than a 5-fold increase. This indicates that the first two electrons are relatively easily removed valence electrons from the outer shell (3s2), while the third electron is removed from a stable, inner noble gas core (2p6). Thus, element X has 2 valence electrons and belongs to Group 2 (Magnesium).
7A naturally occurring element X consists of two stable isotopes: 63X (isotopic mass = 62.93 amu, abundance = 69.17%) and 65X (isotopic mass = 64.93 amu, abundance = 30.83%). What is the relative atomic mass of element X?
A.63.55 amu
B.63.93 amu
C.64.00 amu
D.64.31 amu
Explanation: The relative atomic mass is the weighted average of the isotopic masses: Ar = (62.93 * 0.6917) + (64.93 * 0.3083) = 43.5287 + 20.0179 = 63.5466 amu ≈ 63.55 amu. This corresponds to naturally occurring copper (Cu).
8Why does chlorine (Cl) have a more exothermic electron affinity (-349 kJ/mol) than fluorine (F, -328 kJ/mol), contrary to the general periodic trend?
A.Fluorine's 2p subshell is extremely compact, resulting in high electron-electron repulsions that reduce the energy released upon adding an electron
B.Chlorine has a higher electronegativity than fluorine on the Pauling scale
C.Fluorine has more electron shielding than chlorine
D.Chlorine's incoming electron enters an empty 3d orbital rather than a 3p orbital
Explanation: Because fluorine is in Period 2, its 2p orbitals are very small and compact. Adding an extra electron into this small space creates strong interelectronic repulsions among the existing valence electrons, which counteracts some of the nuclear attraction and makes the electron affinity of fluorine less exothermic than that of chlorine.
9According to the Bohr model of the hydrogen atom, an electron transitions from the n = 4 energy level to the n = 2 energy level. Given Rydberg's constant energy factor RH = 2.18 x 10^-18 J and Planck's constant h = 6.626 x 10^-34 J·s, what is the frequency of the emitted photon?
A.6.17 x 10^14 Hz
B.4.09 x 10^14 Hz
C.2.06 x 10^14 Hz
D.8.22 x 10^14 Hz
Explanation: The energy of the emitted photon is given by ΔE = RH * (1/n1^2 - 1/n2^2) = 2.18 x 10^-18 J * (1/2^2 - 1/4^2) = 2.18 x 10^-18 * (1/4 - 1/16) = 2.18 x 10^-18 * (3/16) = 4.0875 x 10^-19 J. Using E = h·ν, the frequency is ν = ΔE / h = (4.0875 x 10^-19 J) / (6.626 x 10^-34 J·s) = 6.169 x 10^14 Hz ≈ 6.17 x 10^14 Hz (corresponding to the H-beta blue-green spectral line at λ = 486 nm).
10Which of the following stable molecules contains an atom that possesses an incomplete (sub-octet) valence shell of six electrons?
A.BF3 (Boron trifluoride)
B.CH4 (Methane)
C.NH3 (Ammonia)
D.SF6 (Sulfur hexafluoride)
Explanation: In BF3, boron (Group 13) has 3 valence electrons and forms three single covalent bonds with fluorine atoms. This leaves boron surrounded by only 6 valence electrons (an incomplete octet), making BF3 an electron-deficient Lewis acid.

About the Angola 12th Grade Chemistry National Exam Exam

This is the INADE 12th-grade national examination in Chemistry (Química), code 127, for eligible students following the Angolan curriculum. The official assessment is an in-person written paper combining selection, chemical representation, calculations, and constructed-response items and uses Portuguese. This page provides an English-language MCQ study adaptation only; official names and target-language material integral to language skills are preserved.

Exam sponsor: Instituto Nacional de Avaliação e de Desenvolvimento da Educação (INADE), Ministério da Educação (MED), Angola. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

INADE administers the 12th-grade Chemistry (Química) paper (code 127) under the 2025/2026 national-exam regulation. The official Information-Prova and published paper define the scope reflected below. The assessment is an in-person written paper combining selection, chemical representation, calculations, and constructed-response items; its official language setting is Portuguese.

Time Limit

120 minutes (+30 minutes tolerance)

Passing Score

The paper is scored from 0 to 200 points and converted to the 0–20 scale. Decreto Executivo 81/26 assigns weighting and progression rules to separate learning-assessment regulations and does not publish a standalone 10/20 pass mark for this paper.

Exam / Certification Fees

No separate candidate exam fee is published in the official 2025/2026 INADE national-exam materials.

Exam sponsor website

Reported exam pass rate: No current subject-specific national pass rate was found in the official INADE materials reviewed.. 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.

Published scope

Reactions, kinetics, and equilibrium

Equations, stoichiometry, reaction rate, equilibrium, acids, bases, and quantitative reasoning.

Published scope

Atomic, molecular, and solution structure

Atomic structure, bonding, intermolecular forces, molecular geometry, solutions, and colligative effects.

Published scope

Electrochemistry

Oxidation and reduction, galvanic and electrolytic cells, electrode potentials, and applications.

Published scope

Coordination and group-14 chemistry

Complex ions, ligands, oxidation states, carbon allotropes, silicon, and group trends.

Published scope

Organic and biological chemistry

Functional groups, reactions, isomerism, carbohydrates, lipids, amino acids, and proteins.

Preparing for the Angola 12th Grade Chemistry National Exam Exam

What You Need to Know

  • Passing score: The paper is scored from 0 to 200 points and converted to the 0–20 scale. Decreto Executivo 81/26 assigns weighting and progression rules to separate learning-assessment regulations and does not publish a standalone 10/20 pass mark for this paper.
  • Assessment: INADE administers the 12th-grade Chemistry (Química) paper (code 127) under the 2025/2026 national-exam regulation. The official Information-Prova and published paper define the scope reflected below. The assessment is an in-person written paper combining selection, chemical representation, calculations, and constructed-response items; its official language setting is Portuguese.
  • Time limit: 120 minutes (+30 minutes tolerance)
  • Exam / certification fees: No separate candidate exam fee is published in the official 2025/2026 INADE national-exam materials. Official sources

Using Our Practice Resources

  • Work through all 88 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

Angola 12th Grade Chemistry National Exam: Suggested Study Strategy

1Use the official Information-Prova to organize review around: Reactions, kinetics, and equilibrium; Atomic, molecular, and solution structure; Electrochemistry; Coordination and group-14 chemistry; Organic and biological chemistry.
2Work through the published official paper and its classification criteria to practise the real response types and required working.
3Use this MCQ bank for concept checks, then practise explanations, calculations, source analysis, or extended writing in the official assessment language.

Frequently Asked Questions

What is the official format?

INADE publishes 15 top-level items for the 2026 paper. It is an in-person written paper combining selection, chemical representation, calculations, and constructed-response items, not a 100-question MCQ test.

How long is the official paper?

The regulation sets 120 minutes plus 30 minutes tolerance for 12th-grade national papers.

How is it scored?

The official paper totals 200 raw points, converted to the 0–20 scale. The current exam regulation refers weighting and progression to separate learning-assessment rules.

Who is eligible?

Eligible 12th-grade students following the Angolan curriculum must be registered in PGDEN and meet the admission conditions in Decreto Executivo 81/26, including the attendance and discipline requirements.

Does this bank reproduce the official exam?

No. These 88 questions are English-language MCQ study adaptations. They are not an official translation, do not reproduce the official item mix, and do not substitute for written-response practice.