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Exam Review

Key Facts: PRC Chemist Exam

70%

Passing Average

RA 10657 Sec. 22

50%

Minimum Per Subject

RA 10657

5

Core Subjects

Board Syllabus

2 days

Exam Duration

PRC Schedule

RA 10657

Governing Law

Chemistry Profession Act

Php 900

Exam Fee

PRC LERIS

The Chemist Licensure Examination is a two-day, computer-based professional board exam administered by the PRC Board of Chemistry under the Chemistry Profession Act (RA 10657). It covers five subjects: Inorganic Chemistry (25%), Analytical Chemistry (25%), Physical Chemistry (20%), Organic Chemistry (15%), and Biochemistry (15%). Passing requires a 70% weighted general average with no rating below 50% in any subject. An examinee who fails but passes any two subjects automatically qualifies as a chemical technician.

Sample PRC Chemist Practice Questions

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

1According to molecular orbital theory, what is the bond order and magnetic behavior of the diatomic oxygen molecule (O2) in its ground state?
A.Bond order 2, paramagnetic
B.Bond order 2, diamagnetic
C.Bond order 1.5, paramagnetic
D.Bond order 2.5, diamagnetic
Explanation: The molecular orbital configuration of O2 is σ1s² σ*1s² σ2s² σ*2s² σ2pz² π2px² π2py² π*2px¹ π*2py¹. The bond order is calculated as (10 bonding electrons - 6 antibonding electrons) / 2 = 2. Because there are two unpaired electrons in the degenerate π* antibonding orbitals, O2 is paramagnetic in its ground state.
2For an octahedral coordination complex of a d5 transition metal ion like Fe(III), which set of conditions favors a low-spin configuration?
A.A strong-field ligand like CN⁻ and large crystal field splitting energy (Δo > P)
B.A weak-field ligand like F⁻ and small crystal field splitting energy (Δo < P)
C.A strong-field ligand like CN⁻ and small pairing energy (Δo < P)
D.A weak-field ligand like Cl⁻ and large pairing energy (Δo > P)
Explanation: A low-spin configuration is favored when the crystal field splitting energy (Δo) is greater than the electron pairing energy (P). Strong-field ligands like cyanide (CN⁻) induce a large splitting Δo, forcing the d-electrons to pair up in the lower-energy t2g orbitals instead of occupying the higher-energy eg orbitals, yielding a t2g⁵ eg⁰ arrangement with one unpaired electron.
3Which of the following d-electron configurations is most susceptible to a strong Jahn-Teller distortion in an octahedral coordination complex?
A.High-spin d4
B.Low-spin d6
C.d3
D.d10
Explanation: Jahn-Teller distortion is most pronounced when there is asymmetric occupancy of the eg orbitals, as they point directly at the ligands. A high-spin d4 complex has a t2g³ eg¹ configuration, which has a single electron in the eg pair (eg orbitals are asymmetrically filled), leading to significant distortion. Low-spin d6 (t2g⁶ eg⁰), d3 (t2g³ eg⁰), and d10 (t2g⁶ eg⁴) complexes have symmetrically filled orbitals and show little or no distortion.
4Under the Hard-Soft Acid-Base (HSAB) principle, which of the following pairs is expected to form the most stable coordination complex?
A.Hg²⁺ (soft acid) and I⁻ (soft base)
B.Fe³⁺ (hard acid) and I⁻ (soft base)
C.Hg²⁺ (soft acid) and F⁻ (hard base)
D.Li⁺ (hard acid) and I⁻ (soft base)
Explanation: The HSAB principle states that hard acids prefer to coordinate with hard bases (primarily electrostatic interactions) and soft acids prefer to coordinate with soft bases (primarily covalent interactions). Hg²⁺ is a large, highly polarizable cation (soft acid) and I⁻ is a large, polarizable anion (soft base), making their interaction highly stable and favorable.
5What is the molecular point group of the sulfur hexafluoride (SF6) molecule?
A.Oh
B.D4h
C.Td
D.C4v
Explanation: Sulfur hexafluoride (SF6) has an octahedral molecular geometry with six equivalent fluorine atoms surrounding a central sulfur atom. The molecule has high symmetry including a center of inversion, multiple C4, C3, and C2 axes, and horizontal/vertical mirror planes, which assigns it to the Oh point group.
6Which of the following represents the correct order of increasing crystal field splitting energy (Δ) according to the spectrochemical series for ligands?
A.Cl⁻ < H2O < NH3 < CN⁻
B.CN⁻ < NH3 < H2O < Cl⁻
C.Cl⁻ < NH3 < H2O < CN⁻
D.H2O < Cl⁻ < NH3 < CN⁻
Explanation: The spectrochemical series ranks ligands based on the magnitude of d-orbital splitting they induce in transition metal complexes. Halide ions (like Cl⁻) are weak-field ligands, oxygen-donors (like H2O) are intermediate, nitrogen-donors (like NH3) are strong, and carbon-donors (like CN⁻ or CO) are very strong π-acceptor ligands, leading to the order: Cl⁻ < H2O < NH3 < CN⁻.
7Based on Wade's rules (polyhedral skeletal electron pair theory), what is the classification of the borane cluster B5H9?
A.Nido-borane
B.Closo-borane
C.Arachno-borane
D.Hypho-borane
Explanation: Wade's rules classify boranes by the relationship between the number of boron atoms (n) and the number of skeletal electron pairs. For B5H9, we assume 5 B-H units contributing 2 skeletal electrons each (10 electrons) and 4 extra hydrogen atoms contributing 1 skeletal electron each (4 electrons), giving a total of 14 skeletal electrons or 7 pairs. Since 7 pairs equals n + 2 skeletal pairs (where n = 5), the cluster is classified as a nido-borane.
8What type of semiconductor is produced when silicon is doped with a small amount of gallium?
A.p-type semiconductor
B.n-type semiconductor
C.Intrinsic semiconductor
D.Degenerate metal
Explanation: Silicon has 4 valence electrons. Doping silicon with gallium (which belongs to Group 13 and has 3 valence electrons) creates electron deficiencies or "holes" in the valence band. Because the dominant charge carriers are positive holes, it is classified as a p-type semiconductor.
9Which of the following compounds displays the highest lattice energy?
A.MgO
B.NaCl
C.LiF
D.KBr
Explanation: Lattice energy is proportional to (Q1 * Q2) / d, where Q1 and Q2 are ionic charges and d is the internuclear distance. MgO is composed of Mg²⁺ and O²⁻ ions (charge product of 4), while NaCl, LiF, and KBr are composed of monovalent ions (charge product of 1). The higher ionic charge in MgO outweighs any difference in ionic radius, resulting in the highest lattice energy.
10According to molecular orbital theory, why is the nitric oxide molecule (NO) paramagnetic, and what happens to its bond order when it is oxidized to the nitrosonium ion (NO⁺)?
A.NO has 1 unpaired electron in a π* orbital; upon oxidation to NO⁺, this electron is removed, increasing the bond order from 2.5 to 3.
B.NO has 1 unpaired electron in a σ orbital; upon oxidation to NO⁺, this electron is removed, decreasing the bond order from 2.5 to 2.
C.NO has 2 unpaired electrons in π* orbitals; upon oxidation to NO⁺, both are removed, increasing the bond order from 2 to 3.
D.NO has 1 unpaired electron in a π* orbital; upon oxidation to NO⁺, this electron remains, and the bond order stays at 2.5.
Explanation: Nitric oxide (NO) is a heteronuclear diatomic molecule with 15 valence electrons. Its molecular orbital configuration places the 15th electron in a π*2p antibonding orbital, making it paramagnetic with one unpaired electron and a bond order of 2.5. Upon oxidation to NO⁺, the electron is removed from this π* orbital, resulting in a diamagnetic ion with a stronger bond order of 3.

About the PRC Chemist Exam

The PRC Chemist Licensure Examination is the national licensing board exam required to practice chemistry in the Philippines under Republic Act No. 10657. It covers five core subjects: Analytical Chemistry, Inorganic Chemistry, Physical Chemistry, Organic Chemistry, and Biochemistry. Candidates must achieve a weighted average of at least 70% with no grade below 50% in any subject to obtain their license and register as a chemist.

Exam sponsor: Professional Regulatory Board of Chemistry under the PRC. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Question count not published by the exam provider

Time Limit

Two-day board examination (16 hours total testing time across five subjects)

Passing Score

70% weighted average, no rating below 50%

Exam / Certification Fees

Php 900.00

Exam sponsor website

Reported exam pass rate: 73.22% (October 2025). 842 of 1,150 examinees passed in October 2025 and 592 of 1,088 in October 2024 (PRC); rates vary by administration 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.

25%

Inorganic Chemistry

Atomic structure, chemical bonding models, transition metal and coordination chemistry, solid state lattice systems, and periodic table trends.

25%

Analytical Chemistry

Measurements and quality assurance, equilibria, separations, gravimetry and titrimetry, electrochemical and instrumental methods (GC, HPLC, AAS, ICP, MS, UV-Vis, IR, NMR), lab safety, and method development.

20%

Physical Chemistry

Chemical thermodynamics, kinetics, phase equilibria, solutions, electrochemistry, and quantum mechanics fundamentals.

15%

Organic Chemistry

IUPAC nomenclature, stereochemistry (R/S and conformations), reaction mechanisms (substitution, elimination, addition), aromaticity, and synthesis.

15%

Biochemistry

Structures of biomolecules (proteins, carbohydrates, lipids, DNA/RNA), enzyme kinetics (Michaelis-Menten), and cellular metabolic pathways.

Preparing for the PRC Chemist Exam

What You Need to Know

  • Passing score: 70% weighted average, no rating below 50%
  • Assessment: Question count not published by the exam provider
  • Time limit: Two-day board examination (16 hours total testing time across five subjects)
  • Exam / certification fees: Php 900.00 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

PRC Chemist: Suggested Study Strategy

1Concentrate on Analytical and Inorganic Chemistry first, as they represent 50% of the total exam weight.
2Drill quantitative calculation problems in Physical Chemistry (thermodynamics and kinetics) and Analytical Chemistry (gravimetry/titrations).
3Understand organic reaction mechanisms (SN1, SN2, E1, E2) and NMR/IR spectral interpretations.
4Review laboratory safety and quality assurance (tested in Analytical Chemistry) and learn the key provisions of RA 10657 for professional practice.
5Take timed mock exams to pace yourself for a two-day, 16-hour testing format.

Frequently Asked Questions

What is the passing score for the PRC Chemist Board Exam?

You must obtain a weighted general average rating of at least 70%, with no rating below 50% in any of the five professional subjects. Earning below 50% in any single subject will result in a failure regardless of how high your overall average is.

Can I register as a Chemical Technician if I fail the Chemist exam?

Yes. Section 22(a) of RA 10657 provides that an examinee who fails the Chemist Licensure Examination but passes any two (2) subjects automatically qualifies as a chemical technician, without a separate exam.

What law regulates the chemistry profession in the Philippines?

The chemistry profession is governed by Republic Act No. 10657, the Chemistry Profession Act, approved on March 27, 2015. It repealed RA 754, defines the scope of practice of chemists and chemical technicians, requires certificates of authority for chemical laboratories, and makes chemistry documents official only when signed by a registered chemist.

How long is the Chemist Licensure Examination?

The exam is administered over two consecutive days, totaling 16 hours of examination time across five subjects: Day 1 covers Inorganic Chemistry (4 hours) and Analytical Chemistry (4 hours); Day 2 covers Physical Chemistry (3 hours), Organic Chemistry (2.5 hours), and Biochemistry (2.5 hours).