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100+ Free Public Institution Category C (Natural Sciences) Practice Questions

Prepare for the China Public Institution Recruitment Examination — Category C Natural Sciences Technical (全国事业单位公开招聘分类考试 — 自然科学专技类 C类) exam with instant access — no signup required.

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Public Institution Exam — Category A Comprehensive Management (事业单位 A类 综合管理, China)

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Public Institution Exam — Category B Social Sciences Technical (事业单位 B类 社会科学专技, China)

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Public Institution Exam — Category D Primary & Secondary Teachers (事业单位 D类 中小学教师, China)

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Public Institution Exam — Category E Medical & Health (事业单位 E类 医疗卫生, China)

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2026 Statistics

Key Facts: Public Institution Category C (Natural Sciences) Exam

210 Minutes

Total Unified Examination Sitting Duration (90 min Paper 1 + 120 min Paper 2)

MOHRSS Public Institution Unified Examination Syllabus

300 Points

Total Combined Maximum Score (150 pts Paper 1 + 150 pts Paper 2)

MOHRSS Center for Personnel Testing and Assessment

Category C

Dedicated STEM Track (自然科学专技类) for Scientific Research & Engineering Posts

National Classification Guidelines for Public Institution Recruitment

STEM Degree

Required Educational Background in Science, Engineering, Agronomy, or IT

MOHRSS Eligibility Directory

Semi-Annual

Unified National Examination Sessions (Spring / Autumn Rounds)

CPTA Examination Schedules

MOHRSS CPTA

National Examination Authority and Syllabus Administrator

Ministry of Human Resources and Social Security of the PRC

The China Public Institution Category C (Natural Sciences) Exam is the premier competitive entrance qualification for scientific, technical, and engineering posts across China's state institutions. The unified examination consists of two papers: Occupational Aptitude Test C (100 MCQs, 90 min) and Comprehensive Application Ability C (written experimental design & literature analysis, 120 min), totaling 300 points over 210 minutes. This 100-question practice module provides bilingual Chinese-English mastery across all five core syllabus modules.

Sample Public Institution Category C (Natural Sciences) Practice Questions

Try these sample questions to test your Public Institution Category C (Natural Sciences) exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1During an orbital rendezvous and docking maneuver between the Shenzhou spacecraft and the Tiangong space station, both spacecraft fire micro-thrusters in a vacuum. Which fundamental physical principle directly explains the propulsion generated by expelling reaction mass in the absence of an external medium?
A.Law of Conservation of Momentum (动量守恒定律)
B.Bernoulli's Principle (伯努利原理)
C.Archimedes' Buoyancy Principle (阿基米德浮力定律)
D.Coulomb's Electrostatic Law (库仑定律)
Explanation: Rocket propulsion in a vacuum operates directly on Newton's Third Law of Motion and the Law of Conservation of Momentum (动量守恒定律). In a closed system, the forward momentum gained by the spacecraft is exactly equal and opposite to the backward momentum of the expelled high-velocity exhaust gas (m_spacecraft * Delta_v = - m_gas * v_exhaust). It does not require any ambient atmospheric medium to push against.
2Modern fiber optic communication networks (光纤通信) transmit high-speed data pulses across continental distances. Which optical phenomenon ensures that light signals remain confined inside the fiber's core glass without leaking into the cladding?
A.Total Internal Reflection (全反射)
B.Optical Polarization (光的偏振)
C.Diffraction of Light (光的衍射)
D.Photoelectric Effect (光电效应)
Explanation: Optical fibers rely on Total Internal Reflection (全反射). When light travels from a core medium with a higher refractive index (n_core) toward a cladding medium with a lower refractive index (n_cladding) at an incident angle greater than the critical angle (theta > theta_c = arcsin(n_cladding / n_core)), 100% of the optical energy is reflected back into the core with zero refractive leakage.
3According to the Second Law of Thermodynamics and Carnot's Theorem, what is the theoretical maximum thermal efficiency (eta_max) of a heat engine operating between a high-temperature heat reservoir at 600 K (T_H) and a cooling reservoir at 300 K (T_C)?
A.50%
B.100%
C.33.3%
D.75%
Explanation: Carnot's theorem establishes that the maximum theoretical thermal efficiency of any heat engine operating between two thermal reservoirs at absolute temperatures T_H and T_C is given by eta_Carnot = 1 - (T_C / T_H). Substituting the values: eta = 1 - (300 K / 600 K) = 1 - 0.50 = 0.50 (50%). No real heat engine can exceed this limit due to irreversible entropy generation.
4High-speed maglev trains and electromagnetic braking systems utilize non-contact eddy current brakes (电涡流制动). When a conductive non-magnetic copper/aluminum plate moves through a stationary magnetic field, braking forces arise primarily because:
A.Induced eddy currents generate magnetic fields that oppose the relative motion per Lenz's Law (楞次定律)
B.The plate develops static electrical charge that attracts the permanent magnet poles
C.Frictional contact between air molecules and magnetic flux lines converts kinetic energy into thermal energy
D.The magnetic field alters the nuclear structure of copper atoms, creating permanent ferromagnetism
Explanation: As the conductive metal plate moves across a magnetic field, the changing magnetic flux induces circulating electrical currents (eddy currents / 涡流) within the metal per Faraday's Law. According to Lenz's Law (楞次定律), these induced currents generate their own magnetic field that exerts a Lorentz force opposing the relative motion between the conductor and the magnetic field, smoothly converting mechanical kinetic energy into Joule heating without mechanical friction.
5In the third period (Period 3: Na to Ar) of the Periodic Table of Elements, which of the following elements has the highest first ionization energy (第一电离能)?
A.Argon (Ar)
B.Sodium (Na)
C.Chlorine (Cl)
D.Silicon (Si)
Explanation: First ionization energy is the energy required to remove the most loosely held valence electron from an isolated gaseous atom. Across a period from left to right, effective nuclear charge increases and atomic radius contracts. Argon (Ar, atomic number 18) possesses a stable octet electron configuration (3s^2 3p^6) in its outermost shell, giving it the highest first ionization energy in Period 3.
6In commercial lithium-ion secondary batteries (锂离子电池), what is the primary function of the Solid Electrolyte Interphase (SEI膜 / 固体电解质界面膜) formed on the graphite anode surface during the initial formation cycle?
A.Allowing selective Li+ transport while passivating the anode to prevent ongoing electrolyte decomposition
B.Conducting electrons directly between the anode and cathode to eliminate external wiring
C.Acting as a sacrificial cathode material to donate extra lithium ions during overdischarge
D.Generating hydrogen gas to pressurize the battery casing and lower internal resistance
Explanation: The Solid Electrolyte Interphase (SEI膜) is a passivating passivation layer formed by the reduction decomposition of electrolyte components on the graphite anode during initial charging. A stable SEI layer is an electronic insulator (preventing continuous electron transfer that would consume liquid electrolyte) but a good Li+ ionic conductor, allowing reversible intercalation and de-intercalation of lithium ions while preserving battery cycle life.
7Human blood pH is tightly regulated within the narrow physiological range of 7.35 to 7.45. Which of the following buffer pairs represents the primary extracellular chemical buffer system in human blood plasma?
A.Carbonic acid / Bicarbonate pair (H2CO3 / HCO3-)
B.Dihydrogen phosphate / Hydrogen phosphate pair (H2PO4- / HPO4^2-)
C.Hydrochloric acid / Sodium chloride pair (HCl / NaCl)
D.Acetic acid / Sodium acetate pair (CH3COOH / CH3COONa)
Explanation: The carbonic acid-bicarbonate buffer system (H2CO3 / HCO3- / 碳酸-碳酸氢盐缓冲系统) is the principal extracellular buffer in human blood. It is uniquely effective because it is an open system: excess volatile acid (H2CO3) can be rapidly exhaled as CO2 by the respiratory system, while base (HCO3-) concentration is regulated by renal excretion and reabsorption.
8Polymers are synthesized via different reaction pathways. Which of the following polymers is produced through a step-growth Condensation Polymerization (缩聚反应) that eliminates small molecules such as water or ethylene glycol during chain growth?
A.Polyethylene terephthalate (PET / 聚对苯二甲酸乙二醇酯)
B.Polyethylene (PE / 聚乙烯)
C.Polypropylene (PP / 聚丙烯)
D.Polyvinyl chloride (PVC / 聚氯乙烯)
Explanation: Polyethylene terephthalate (PET) is synthesized via condensation polymerization (polycondensation) between terephthalic acid (or dimethyl terephthalate) and ethylene glycol, forming ester linkages (-COO-) while releasing water (or methanol) as a small byproduct. In contrast, PE, PP, and PVC are formed via addition polymerization (加聚反应) across carbon-carbon double bonds without generating byproducts.
9According to Mitchell's Chemiosmotic Hypothesis (化学渗透假说), what directly drives the catalytic synthesis of ATP by ATP Synthase in both mitochondrial oxidative phosphorylation and chloroplast photophosphorylation?
A.An electrochemical transmembrane proton gradient (质子电化学梯度 / 质子动势)
B.Direct mechanical collision between glucose molecules and the cell nucleus
C.The spontaneous hydrolytic cleavage of nuclear DNA phosphodiester bonds
D.Electrostatic repulsion between sodium and potassium ions in the cytoplasm
Explanation: Peter Mitchell's chemiosmotic hypothesis explains that the electron transport chain pumps protons (H+) across a biological membrane (mitochondrial inner membrane or chloroplast thylakoid membrane), creating a proton concentration gradient and electrical potential difference (proton-motive force). Protons flow back down this electrochemical gradient through the F0 channel of ATP Synthase, driving the rotational mechanical catalysis that phosphorylates ADP into ATP.
10In the CRISPR-Cas9 genome editing system widely used in molecular biology, what determines the specific genomic site where the Cas9 endonuclease introduces a double-strand break (DSB)?
A.Base-pairing complementarity between the single guide RNA (sgRNA) spacer and target DNA, adjacent to a Protospacer Adjacent Motif (PAM)
B.Random non-specific electrostatic adhesion to histone protein tails
C.Restriction endonuclease recognition sequences of exactly 6 base pairs without any RNA involvement
D.Temperature-dependent thermal denaturation of DNA telomere repeats
Explanation: CRISPR-Cas9 target specificity is governed by a synthetic single guide RNA (sgRNA). A 20-nucleotide spacer sequence on the sgRNA hybridizes via Watson-Crick base pairing to the complementary genomic target DNA strand immediately 5' of a 3-nucleotide Protospacer Adjacent Motif (PAM sequence, typically 5'-NGG-3' for SpCas9). Upon PAM recognition and RNA-DNA pairing, the Cas9 endonuclease domains (RuvC and HNH) cleave both DNA strands.

About the Public Institution Category C (Natural Sciences) Exam

The China Public Institution Recruitment Examination — Category C Natural Sciences Technical (全国事业单位公开招聘分类考试 — 自然科学专技类 C类) is the standardized national competitive examination for recruiting technical and scientific research personnel into China's state research institutes, geological and meteorological bureaus, agricultural academies, environmental monitoring centers, IT research laboratories, and engineering institutions. Administered under the unified outline of the Ministry of Human Resources and Social Security (MOHRSS), the exam tests natural science fundamentals, technical text comprehension, quantitative and experimental data analysis, judgment reasoning, scientific literature analysis, experimental design, and empirical error evaluation.

Assessment

Paper 1: 职业能力倾向测验（C类）(Occupational Aptitude Test C: 100 MCQs, 90 mins, 150 pts); Paper 2: 综合应用能力（C类）(Comprehensive Application Ability C: Subjective written sci-tech case & experimental analysis, 120 mins, 150 pts); Total 210 mins.

Time Limit

210 minutes total (Paper 1: 90 minutes; Paper 2: 120 minutes)

Passing Score

Set by the current recruiting jurisdiction and position-ranking rules

Exam Fee

Set by the recruiting jurisdiction (Ministry of Human Resources and Social Security (MOHRSS CPTA) & Provincial Personnel Examination Centers)

Public Institution Category C (Natural Sciences) Exam Content Outline

20%

Science & Technology Foundations (科技与科学常识)

Evaluates fundamental and cutting-edge principles across physics (mechanics, thermodynamics, electromagnetism, optics), chemistry (periodic periodicity, redox mechanisms, polymers, battery chemistry), biology (cellular energetics, genetics, CRISPR, carbon cycles), earth and atmospheric sciences (plate tectonics, meteorology, oceanography), and information technology (computer architecture, networking, quantum computing, and national sci-tech mega-projects).

20%

Scientific Text Comprehension (言语理解与表达)

Assesses analytical comprehension of complex scientific literature, technical abstracts, and research reports: extracting core themes, evaluating logical structure and syntactic flow, identifying precise scientific terminology (such as accuracy vs precision), interpreting causal mechanisms, and detecting rhetorical intent or unwarranted claims.

20%

Quantitative Reasoning & Experimental Data Analysis (数量关系与实验资料分析)

Tests numerical computation in scientific contexts (kinetic energy, molar concentration, gas laws, radioactive decay, circuit resistance) and interpretation of high-density experimental datasets, calibration curves, multi-parameter response plots, chromatography peak metrics, and statistical error propagation formulas.

15%

Judgment & Scientific Reasoning (判断推理)

Focuses on formal deductive and inductive scientific reasoning: matching operational scientific definitions, spatial reasoning of 3D molecular conformations and crystal nets, hypothesis strengthening and weakening analysis, identifying logical fallacies in experimental arguments, and solving multi-premise technical rule systems.

25%

Experimental Design & Scientific Analysis (实验设计与科技文献综合分析)

Covers practical research methodology and comprehensive application ability: defining independent/dependent/controlled variables, establishing positive and negative control groups, setting up double-blind RCT protocols, orthogonal array design, diagnosing systematic versus random errors, identifying instrument calibration drift, selecting analytical blanks, and evaluating methodological validity.

How to Pass the Public Institution Category C (Natural Sciences) Exam

What You Need to Know

  • Passing score: Set by the current recruiting jurisdiction and position-ranking rules
  • Assessment: Paper 1: 职业能力倾向测验（C类）(Occupational Aptitude Test C: 100 MCQs, 90 mins, 150 pts); Paper 2: 综合应用能力（C类）(Comprehensive Application Ability C: Subjective written sci-tech case & experimental analysis, 120 mins, 150 pts); Total 210 mins.
  • Time limit: 210 minutes total (Paper 1: 90 minutes; Paper 2: 120 minutes)
  • Exam fee: Set by the recruiting jurisdiction

Keys to Passing

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

Public Institution Category C (Natural Sciences) Study Tips from Top Performers

1Master Core Multi-Disciplinary Science Fundamentals: Review fundamental concepts across physics, chemistry, biology, earth science, and computing, especially energy conservation, redox potentials, enzyme kinetics, plate tectonics, and network models.
2Understand Experimental Control Methodologies: Be able to instantly identify independent variables, dependent response variables, extraneous confounding factors, positive control groups, and negative control groups in diverse experimental setups.
3Distinguish Error Types & Instrument Calibrations: Learn to clearly differentiate systematic error (instruments drift, calibration offset, parallax) from random error (thermal noise, ambient fluctuations) and know proper mitigation strategies.
4Develop Speed in Technical Data Chart Interpretation: Practice reading multi-axis graphs, calibration curves, spectrometry peaks, and chromatographic metrics quickly without getting bogged down by extraneous background context.
5Internalize Orthogonal Array Design Principles: Understand how orthogonal testing tables (Ln(p^k)) balance factor levels and minimize the required experimental runs while screening key parameter interactions.
6Train on Scientific Literature Argumentation Evaluation: Focus on spotting unsupported extrapolations, non-sequiturs, confusion between correlation and causation, and insufficient statistical sample sizes.

Frequently Asked Questions

What is China's Public Institution Category C (Natural Sciences) Exam and who is it designed for?

The Public Institution Category C Exam (全国事业单位公开招聘分类考试 - 自然科学专技类 C类) is China's official standardized recruitment examination for technical and scientific specialist posts (自然科学专业技术岗位). It is specifically tailored for STEM graduates entering research academies, meteorological services, geological survey bureaus, agricultural research institutes, environmental monitoring stations, software and IT public centers, and engineering design units.

What is the examination structure, duration, and scoring system?

The examination is administered in a single continuous testing session (typically on a Saturday morning) comprising two papers: Paper 1 《职业能力倾向测验（C类）》(Occupational Aptitude Test C, 100 objective questions, 90 minutes, 150 points) and Paper 2 《综合应用能力（C类）》(Comprehensive Application Ability C, subjective written sci-tech literature analysis, experimental design, and data critique, 120 minutes, 150 points). The total combined testing time is 210 minutes with a maximum score of 300 points.

How does Category C differ from Categories A, B, D, and E in Public Institution recruitment?

China's unified public institution recruitment categorizes posts into five distinct tracks: Category A (Comprehensive Management / 综合管理类), Category B (Humanities and Social Sciences / 社会科学专技类), Category C (Natural Sciences and Engineering / 自然科学专技类), Category D (Primary & Secondary Education / 中小学教师类), and Category E (Healthcare & Medical / 医疗卫生类). Category C uniquely emphasizes STEM domain knowledge, scientific literature comprehension, empirical data calculation, and experimental design methodologies.

What educational qualifications and eligibility criteria apply to Category C applicants?

Candidates must hold an MoE-recognized degree (typically Bachelor's, Master's, or PhD) in STEM fields including physics, chemistry, biology, earth sciences, mathematics, computer science, civil/mechanical/electrical engineering, agronomy, or environmental science. Candidates must be PRC citizens under the age threshold (typically 35 years, relaxed to 40 for doctorates or senior professional titles) with a clean background check.

Why is this OpenExamPrep practice bank presented in English?

While the official MOHRSS examination in China is administered in Simplified Chinese, this OpenExamPrep module provides 100 high-yield, technically rigorous multiple-choice questions in English to serve bilingual researchers, international STEM scholars, and dual-language technical personnel. Authentic Chinese terminology (e.g. 职业能力倾向测验, 综合应用能力, 实验设计, 系统误差, 正交试验) is integrated throughout to provide seamless bilingual conceptual alignment.