FIA PAST PAPERS
FIA Past Papers, Syllabus(Download Pdf). FIA Solved Past Papers MCQs section cover and solved the past papers of all FIA posts like AD, SI, Inspector, Computer Operator, UDC, LDC.
A.
Cloud computing is older; edge is newer
B.
Cloud processes data on centralized servers; edge processes data near the source.
C.
Cloud is local; edge is global
D.
Cloud uses cables; edge is entirely wireless
Correct answer is:
B. Cloud processes data on centralized servers; edge processes data near the source.
Explanation:
The correct answer is Cloud processes data on centralized servers; edge processes data near the source. because it accurately reflects the architectural differences in data processing locations.
- Step 1 (Centralized Architecture): Cloud computing relies on massive, geographically centralized data centers to process, store, and manage global consumer data over the internet.
- Step 2 (Decentralized Local Architecture): Edge computing brings computation and storage directly to local hardware nodes or IoT devices, processing data immediately where it is gathered to reduce latency.
- Incorrect Options:
- Cloud computing is older; edge is newer is incorrect because age is an arbitrary timeline detail rather than the core architectural distinction between them.
- Cloud is local; edge is global is incorrect because it reverses reality; cloud resources span global networks while edge environments focus on local proximity.
- Cloud uses cables; edge is entirely wireless is incorrect because both frameworks utilize combinations of fiber optic wiring and wireless communication layers.
Computer MCQs for Competitive Exams Constable Model Past paper 2025 PDF
A.
A bug fixed on the day of software release
B.
A security flaw unknown to the vendor.
C.
A virus that expires within 24 hours
D.
A hardware defect
Correct answer is:
B. A security flaw unknown to the vendor.
Explanation:
The correct answer is A security flaw unknown to the vendor. because the term signifies that the developer or vendor has had zero days to create a security patch for the issue.
- Step 1 (Definition): A zero-day vulnerability is an unpatched software flaw that is completely unknown to the party responsible for fixing it, often discovered by attackers first.
- Step 2 (Exploitation): Because the vendor is unaware of the defect, no official defense or patch exists, making systems highly susceptible to targeted zero-day exploits.
- Incorrect Options:
- A bug fixed on the day of software release is incorrect because bugs patched at launch are known and resolved, not exposed security flaws.
- A virus that expires within 24 hours is incorrect because malware lifetime is not restricted by a mandatory 24-hour self-destruction timer.
- A hardware defect is incorrect because zero-day vulnerabilities primarily refer to flaws discovered within software code and system logic.
Computer MCQs for Competitive Exams Constable Model Past paper 2025 PDF
A.
High-speed internet routing
B.
Decentralized and immutable digital ledger.
C.
Centralized cloud storage system
D.
Automated video editing features
Correct answer is:
B. Decentralized and immutable digital ledger.
Explanation:
The correct answer is Decentralized and immutable digital ledger. because it records transactions sequentially across a peer-to-peer network without relying on a central authority.
- Step 1 (Decentralization): Data is stored across a distributed network of computers (nodes) rather than a single centralized server, ensuring no single entity has total control.
- Step 2 (Immutability): Once a block of data is cryptographically linked to the chain, modifying it requires altering all subsequent blocks, making the records practically unchangeable.
- Incorrect Options:
- High-speed internet routing is incorrect because network routing protocols handle internet traffic speeds, which is entirely separate from cryptographic ledgers.
- Centralized cloud storage system is incorrect because blockchain is inherently decentralized, which is the direct opposite of a centralized framework.
- Automated video editing features is incorrect because media rendering software operates on completely different algorithms unrelated to ledger distribution.
Computer MCQs for Competitive Exams Constable Model Past paper 2025 PDF
A.
Upgrading computer operating systems
B.
Fraudulent messages used to steal personal information.
C.
Backing up network data safely
D.
Sorting files into folders
Correct answer is:
B. Fraudulent messages used to steal personal information.
Explanation:
The correct answer is Fraudulent messages used to steal personal information. because phishing relies on digital deception to manipulate targets into giving up data voluntarily.
- Step 1 (Deceptive Tactics): Attackers distribute fraudulent emails, text messages, or spoofed web links disguised as communications from legitimate organizations like banks, utilities, or employers.
- Step 2 (Credential Harvesting): The goal is to trick users into revealing confidential information, such as login credentials, credit card details, or social security numbers, which are then exploited for identity theft or unauthorized access.
- Incorrect Options:
- Upgrading computer operating systems is incorrect because OS upgrades are regular administrative software maintenance routines.
- Backing up network data safely is incorrect because data backup is a defensive cybersecurity protocol used to preserve files against unexpected loss.
- Sorting files into folders is incorrect because arranging items inside folders is an everyday digital storage organization task.
Computer MCQs for Competitive Exams Constable Model Past paper 2025 PDF
A.
India
B.
Pakistan.
C.
England
D.
Australia
Correct answer is:
B. Pakistan.
Explanation:
The correct answer is Pakistan. because it was designated by the International Cricket Council (ICC) as the official primary host nation for the tournament, marking the return of a major ICC event to the country.
- Step 1 (Official Host Status): The Pakistan Cricket Board (PCB) held the official hosting rights for the 2025 ICC Champions Trophy, scheduling matches across venues in Karachi, Lahore, and Rawalpindi.
- Step 2 (Hybrid Model Context): Due to political tensions and India's refusal to travel to Pakistan, a hybrid hosting model was utilized, resulting in the United Arab Emirates (UAE) co-hosting to stage India's fixtures and the final match.
- Incorrect Options:
- India is incorrect because while India won the tournament, they boycotted travelling to the host nation and singularly host the 2029 edition instead.
- England is incorrect because England last hosted the event in 2017 and was not designated to host the 2025 cycle.
- Australia is incorrect because Australia holds no hosting assignments for this specific edition of the tournament.
Constable Model Past paper 2025 PDF Current Affair General Knowledge MCQs
A.
Iran
B.
India
C.
Afghanistan.
D.
China
Correct answer is:
C. Afghanistan.
Explanation:
The correct answer is Afghanistan. because the Pakistan Air Force executed multiple cross-border air operations targeting safe houses inside Afghan territory.
- Step 1 (Military Operations): Beginning in late February 2026, Pakistan initiated intensive, intelligence-based air operations striking targets across border provinces including Nangarhar, Paktika, and Khost.
- Step 2 (Escalation to Kabul): The cross-border violence escalated further into March 2026, resulting in highly publicized airstrikes extending deep into Afghan territory, including the capital city of Kabul.
- Incorrect Options:
- Iran is incorrect because while historical border skirmishes have occurred, Pakistan's 2026 air campaigns specifically focused northward.
- India is incorrect because no active conventional military airstrikes were executed across the Line of Control or international border with India.
- China is incorrect because China maintains an active strategic economic alliance with Pakistan, presenting completely stable borders.
Constable Model Past paper 2025 PDF Current Affair General Knowledge MCQs
A.
TTP
B.
Balochistan Liberation Army (BLA).
C.
Al-Qaeda
D.
ISIS
Correct answer is:
B. Balochistan Liberation Army (BLA).
Explanation:
The correct answer is Balochistan Liberation Army (BLA). because it operates as a prominent ethno-nationalist separatist militant organization fighting against state forces in Balochistan.
- Step 1 (Group Focus): Established to seek independent separation or greater autonomy for the Baloch people, the BLA specifically restricts its geographical operations and targets to Balochistan and related state infrastructure.
- Step 2 (Tactical Operations): The group regularly claims responsibility for targeted attacks against security forces, infrastructure links, and foreign development projects located within the province.
- Incorrect Options:
- TTP is incorrect because the Tehrik-e-Taliban Pakistan is an Islamist militant umbrella group whose operational base is primarily rooted along the northwestern Khyber Pakhtunkhwa border.
- Al-Qaeda is incorrect because it functions as a global transnational network without a specialized focus on regional Baloch eth-separatist conflicts.
- ISIS is incorrect because ISIS or ISKP acts as a global caliphate network targeting broader ideological entities rather than specific provincial separation.
Constable Model Past paper 2025 PDF Current Affair General Knowledge MCQs
A.
BLA
B.
Tehrik-e-Taliban Pakistan (TTP).
C.
ISKP
D.
JuA
Correct answer is:
B. Tehrik-e-Taliban Pakistan (TTP).
Explanation:
The correct answer is Tehrik-e-Taliban Pakistan (TTP). because Pakistan's Ministry of Information confirmed that the 2026 air campaign sought to dismantle cross-border safe houses belonging to this network.
- Step 1 (Casus Belli): Following a devastating wave of cross-border suicide bombings and armed attacks in Islamabad, Bajaur, and Bannu, Pakistan launched retributive strikes against hideouts on Afghan soil.
- Step 2 (Command Target): The Pakistani military directly engaged seven designated operational camps operated by the banned TTP infrastructure (referred to by authorities as Fitna al-Khawarij) located inside eastern Afghanistan.
- Incorrect Options:
- BLA is incorrect because the Balochistan Liberation Army's primary hideouts are localized or structurally separate from the specific TTP camps targeted in this northern cross-border aerial campaign.
- ISKP is incorrect in this single-choice context because while ISKP hideouts were also hit in the response, the TTP remains the primary focus of Pakistan's cross-border security operations.
- JuA is incorrect because Jamaat-ul-Ahrar operates as a fractional offshoot affiliate rather than the overarching target network identified by state defense commands.
Constable Model Past paper 2025 PDF Current Affair General Knowledge MCQs
A.
Nepal
B.
India
C.
Pakistan.
D.
Sri Lanka
Correct answer is:
C. Pakistan.
Explanation:
The correct answer is Pakistan. because the South Asian Olympic Committees unanimously confirmed Pakistan's hosting rights for the upcoming 14th edition of the multi-sport regional games.
- Step 1 (Hosting Confirmation): Following scheduling delays, a high-level meeting of regional National Olympic Committees held on the sidelines of the OCA General Assembly officially ratified Pakistan as the single destination host.
- Step 2 (Timeline Assignment): The event is formally scheduled to be hosted across multiple cities in Pakistan between March 23 and March 31, 2027.
- Incorrect Options:
- Nepal is incorrect because Nepal hosted the previous iteration of the South Asian Games in 2019 and does not hold the 2027 hosting rights.
- India is incorrect because India acts as a participant state in the tournament structure rather than the upcoming cycle host.
- Sri Lanka is incorrect because Sri Lanka's bids to bring back the games have not overridden Pakistan's ratified assignment.
Constable Model Past paper 2025 PDF Current Affair General Knowledge MCQs
A.
KRL
B.
Army
C.
WAPDA.
D.
Navy
Correct answer is:
C. WAPDA.
Explanation:
The correct answer is WAPDA. because the Water and Power Development Authority squad secured the 2026 championship title by defeating KRL in the grand final.
- Step 1 (Final Result): In the tournament final played at the KPT Football Stadium in Karachi on February 15, 2026, WAPDA defeated Khan Research Laboratories (KRL) with a narrow 1-0 scoreline thanks to a late goal by Muhammad Samnan.
- Step 2 (Historic Hat-trick): With this critical victory, WAPDA successfully defended its championship title and achieved a historic hat-trick of consecutive National Challenge Cup tournament wins (2021, 2024, and 2026).
- Incorrect Options:
- KRL is incorrect because they finished the tournament as runners-up after failing to score in the final match.
- Army is incorrect because the Pakistan Army squad fell short in the semi-finals, losing out before the title match.
- Navy is incorrect because the Pakistan Navy team failed to progress through to the knockout stages from the group rounds.
Constable Model Past paper 2025 PDF Current Affair General Knowledge MCQs
A.
Ministry of Defense
B.
Ministry of Interior.
C.
Ministry of Law and Justice
D.
Ministry of Finance
Correct answer is:
B. Ministry of Interior.
Explanation:
The correct answer is Ministry of Interior. because the Federal Investigation Agency (FIA) is organized as a specialized department under the executive jurisdiction of the Interior Ministry.
- Step 1 (Statutory Mandate): Established under the FIA Act of 1974, the agency is tasked with investigating federal crimes, including counter-intelligence, human trafficking, money laundering, and cybercrime.
- Step 2 (Administrative Chain): The Director-General of the FIA reports directly to the Federal Interior Secretary and the Interior Minister, who oversee its operational funding, policy deployment, and executive appointments.
- Incorrect Options:
- Ministry of Defense is incorrect because Defense commands the conventional armed forces and military intelligence organs like the ISI, not civilian federal investigators.
- Ministry of Law and Justice is incorrect because it deals with legal drafting, judicial affairs, and state prosecution framework rather than active law enforcement operations.
- Ministry of Finance is incorrect because it coordinates macroeconomic planning and federal budgeting, holding no direct law enforcement tracking authority.
Constable Model Past paper 2025 PDF
A.
Cultural exchange program
B.
Economic connectivity between Pakistan and China.
C.
Space exploration research
D.
Military defense alliance
Correct answer is:
B. Economic connectivity between Pakistan and China.
Explanation:
The correct answer is Economic connectivity between Pakistan and China. because CPEC is a massive bilateral infrastructure development program designed to link regional trade routes.
- Step 1 (Infrastructure Backbone): As a flagship project of China's Belt and Road Initiative (BRI), CPEC focuses on upgrading Pakistan's energy infrastructure, transport networks, and deep-sea transit routes.
- Step 2 (Trade Optimization): By building pipelines, highways, and specialized economic zones from Gwadar Port to China's Xinjiang region, the corridor dramatically shortens trade transit times for international cargo shipments.
- Incorrect Options:
- Cultural exchange program is incorrect because while cultural ties are encouraged alongside the project, it is primarily a massive economic and industrial framework.
- Space exploration research is incorrect because aerospace technology programs are managed independently by organizations like SUPARCO and CNSA.
- Military defense alliance is incorrect because CPEC is structurally an economic, commercial, and industrial partnership rather than a mutual defense treaty.
Constable Model Past paper 2025 PDF Current Affair General Knowledge MCQs
A.
United Nations
B.
INTERPOL.
C.
Amnesty International
D.
World Bank
Correct answer is:
B. INTERPOL.
Explanation:
The correct answer is INTERPOL. because the International Criminal Police Organization is the preeminent global body facilitating cooperative cross-border law enforcement actions.
- Step 1 (Global Network): Comprising nearly 200 member countries, INTERPOL connects national police forces through a secure global communications network called I-24/7.
- Step 2 (Operational Tools): The entity manages shared databases containing biometric data, stolen property, and missing persons, while distributing international alerts like Red Notices to track global fugitives.
- Incorrect Options:
- United Nations is incorrect because the UN is a broad intergovernmental body focused on international diplomacy, peacekeeping, and global policy development rather than direct police operations.
- Amnesty International is incorrect because it is an independent non-governmental organization (NGO) focused entirely on human rights advocacy.
- World Bank is incorrect because it functions as an international financial institution providing development loans to developing nations.
Constable Model Past paper 2025 PDF
A.
Carbon-12
B.
Carbon-13
C.
Carbon-14.
D.
Carbon-15
Correct answer is:
C. Carbon-14.
Explanation:
The correct answer is Carbon-14. because it is a radioactive isotope used to determine the age of organic materials.
- Step 1 (Radioactive Decay): Carbon-14 is an unstable, radioactive isotope of carbon that decays over time with a predictable half-life of approximately 5,730 years. Organisms absorb it during their lifetimes, and measuring its remaining amount after death allows scientists to accurately calculate elapsed time.
- Step 2 (Dating Range): Because of its specific decay rate, this isotope is ideal for dating archaeological and organic samples up to roughly 50,000 years old.
- Incorrect Options:
- Carbon-12 is incorrect because it is the most common stable isotope of carbon and does not undergo radioactive decay, making it useless for tracking time.
- Carbon-13 is incorrect because it is also a stable isotope of carbon that does not decay over time.
- Carbon-15 is incorrect because it is a highly unstable synthetic isotope with a half-life of less than 2.5 seconds, meaning it vanishes too quickly to be found in nature.
Constable Model Past paper 2025 PDF Every Day Science
A.
World Economic Forum
B.
IMF.
C.
WTO
D.
UNESCO
Correct answer is:
B. IMF.
Explanation:
The correct answer is IMF. because the International Monetary Fund is the key global institution tasked with providing emergency financial stabilization programs to countries facing balance-of-payments crises.
- Step 1 (Stabilization Funding): Pakistan frequently secures financial assistance packages from the IMF to stabilize its foreign exchange reserves, manage international debt, and bridge fiscal deficits.
- Step 2 (Structural Reform): These financial programs are tied to specific economic conditions, requiring structural reforms such as tax adjustments, energy sector changes, and fiscal discipline to restore long-term stability.
- Incorrect Options:
- World Economic Forum is incorrect because the WEF is a non-profit foundation that hosts global leadership summits rather than providing monetary stabilization loans.
- WTO is incorrect because the World Trade Organization sets and regulates international trade rules without managing macroeconomic financial bailout programs.
- UNESCO is incorrect because it is a specialized UN agency dedicated to promoting global education, science, and cultural heritage preservation.
Constable Model Past paper 2025 PDF Current Affair General Knowledge MCQs
A.
Propane
B.
Butane
C.
Methane.
D.
Ethane
Correct answer is:
C. Methane.
Explanation:
The correct answer is Methane. because it is the primary combustible gas produced during the anaerobic breakdown of organic matter.
- Step 1 (Composition Analysis): Biogas is a renewable energy source primarily composed of Methane (CH₄), which typically makes up 50% to 75% of the total volume, alongside Carbon Dioxide (CO₂).
- Step 2 (Energy Source): Methane is the specific component that gives biogas its energy content, allowing it to be captured and burned for heating, electricity, or vehicle fuel.
- Incorrect Options:
- Propane is incorrect because it is a three-carbon alkane dominant in Liquefied Petroleum Gas (LPG), not biological biogas.
- Butane is incorrect because it is a four-carbon alkane used in lighter fluid and LPG, not generated in large quantities by anaerobic digestion.
- Ethane is incorrect because it is a minor trace component in fossil natural gas, but not a primary element of biogas.
Constable Model Past paper 2025 PDF Every Day Science
A.
Archimedes' Principle
B.
Bernoulli’s Principle.
C.
Pascal's Law
D.
Newton's Third Law
Correct answer is:
B. Bernoulli’s Principle.
Explanation:
The correct answer is Bernoulli’s Principle. because it explains how variations in fluid velocity alter static pressure across an aerodynamic surface.
- Step 1 (Velocity and Pressure): Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure. Curved wing shapes cause air to move faster over the top surface.
- Step 2 (Lift Creation): The high velocity over the top generates a lower pressure zone compared to the slower air underneath, resulting in an upward aerodynamic lift force.
- Incorrect Options:
- Archimedes' Principle is incorrect because it dictates buoyant forces in fluids, explaining why boats float, not how aerodynamic wings function.
- Pascal's Law is incorrect because it deals with pressure transmission in enclosed static fluids, forming the basis for hydraulic systems.
- Newton's Third Law is incorrect in this specific option choice context because, while action-reaction forces do contribute to total lift via downwash deflection, Bernoulli's pressure differential is the intended physical principle here.
Constable Model Past paper 2025 PDF Every Day Science
A.
Joy
B.
Anger
C.
Peace
D.
Love
Correct answer is:
B. Anger
Explanation:
The correct answer is Anger because 'wrath' is defined in English lexicography as deep, intense, or vengeful displeasure and rage.
- Step 1 (Definition Alignment): Wrath describes a state of severe, destructive emotional upset, often associated in historical literature with divine retribution or deep human fury.
- Step 2 (Synonym Choice): Among the provided lexical selections, 'anger' serves as the single accurate conceptual match for a state of aggressive emotional hostility.
- Incorrect Options:
- Joy is incorrect because it represents a state of deep happiness and inner satisfaction, serving as an absolute antonym to wrath.
- Peace is incorrect because it describes a serene state of quietude, harmony, and calm, directly opposing aggressive rage.
- Love is incorrect because it indicates profound affection, care, and positive emotional bonding toward a person or subject.
Constable Model Past paper 2025 PDF English Grammar MCQS
A.
Do
B.
Has
C.
Have
D.
Did
Correct answer is:
C. Have
Explanation:
The correct answer is Have because questions tracking lifetime experiences in the present perfect tense require the auxiliary verb 'have' when paired with the subject pronoun 'you'.
- Step 1 (Tense Identification): The presence of the adverb 'ever' along with the past participle 'been' indicates a present perfect tense framework used to query life history up to the current moment.
- Step 2 (Subject-Verb Agreement): The second-person pronoun 'you' always pairs grammatically with the plural inflection form 'have' rather than the singular variant 'has'.
- Incorrect Options:
- Do is incorrect because 'do' functions as a present simple helping verb that requires a base form main verb rather than the past participle 'been'.
- Has is incorrect because 'has' is restricted exclusively to third-person singular subjects such as he, she, or it.
- Did is incorrect because 'did' introduces a simple past interrogation structure that requires a base form infinitive verb rather than a perfect participle.
Constable Model Past paper 2025 PDF English Grammar MCQS
A.
Agrandise
B.
Aggrandize
C.
Agranzide
D.
Agorandise
Correct answer is:
B. Aggrandize
Explanation:
The correct answer is Aggrandize because it is the orthographically accurate spelling of the verb meaning to augment or enhance the status or wealth of an entity.
- Step 1 (Etymological Roots): Derived from the French word 'agrandir', the accepted standard English spelling requires a double consonant 'gg' at the start and finishes with the conventional suffix 'ize'.
- Step 2 (Semantic Use): The verb is regularly applied in political and historical contexts to characterize leaders or empires seeking to artificially elevate their domain or public image.
- Incorrect Options:
- Agrandise is incorrect due to a missing second 'g' consonant at the prefix stage, along with an unaccepted phonetic ending variant.
- Agranzide is incorrect because it structurally scrambles the final syllable, placing the 'z' consonant before the 'n' nasal phoneme.
- Agorandise is incorrect because it inserts an unnecessary vowel 'o' into the initial root, completely breaking the standard pronunciation layout.
Constable Model Past paper 2025 PDF English Grammar MCQS
A.
Army
B.
Martial
C.
Civil
D.
Naval
Correct answer is:
C. Civil
Explanation:
The correct answer is Civil because it represents matters relating to ordinary citizens and non-military public affairs.
- Step 1 (Conceptual Boundaries): 'Military' encompasses the structured state systems, personnel, and hardware designed specifically for warfare and armed combat operations.
- Step 2 (Antonym Extraction): 'Civil' isolates the non-martial, everyday societal framework governing civilian legal affairs, domestic populations, and private community networks.
- Incorrect Options:
- Army is incorrect because it functions as a core structural branch of the armed military apparatus, making it a close synonym.
- Martial is incorrect because it acts as a direct synonym, referring to war-related or military governance structures (e.g., martial law).
- Naval is incorrect because it is an internal military subcategory that refers explicitly to maritime warfare forces and maritime fleets.
Constable Model Past paper 2025 PDF English Grammar MCQS
A.
A brain cell that stops functioning
B.
Protective caps at the end of chromosomes that shorten as cells divide.
C.
A stomach enzyme that breaks down proteins
D.
A type of white blood cell
Correct answer is:
B. Protective caps at the end of chromosomes that shorten as cells divide.
Explanation:
The correct answer is Protective caps at the end of chromosomes that shorten as cells divide. because telomeres prevent DNA degradation, acting as a biological clock for aging cells.
- Step 1 (Structural Protection): Telomeres consist of repetitive, non-coding DNA sequences (TTAGGG) found at the tips of chromosomes, functioning like plastic aglets on shoelaces to keep genetic strands from unraveling or fusing.
- Step 2 (The Hayflick Limit): Due to the end-replication problem, telomeres shorten slightly with each round of cell division. When they become critically short, the cell hits its replication limit, triggering senescence or programmed death.
- Incorrect Options:
- A brain cell that stops functioning is incorrect because senescent neurons describe dying or degraded nervous system tissue, not a chromosome structure.
- A stomach enzyme that breaks down proteins is incorrect because protein-digesting enzymes in the stomach are classified as proteases, such as pepsin.
- A type of white blood cell is incorrect because immune defense cells traveling through the bloodstream are called leukocytes (such as lymphocytes or neutrophils).
Constable Model Past paper 2025 PDF Every Day Science
A.
Fission joins light nuclei; fusion splits heavy nuclei
B.
Fission splits heavy nuclei; fusion joins light nuclei.
C.
Fission requires higher temperature than fusion
D.
Fission produces no radioactive waste
Correct answer is:
B. Fission splits heavy nuclei; fusion joins light nuclei.
Explanation:
The correct answer is Fission splits heavy nuclei; fusion joins light nuclei. because it accurately defines the opposite atomic mechanics powering both nuclear reactions.
- Step 1 (Fission Mechanics): Nuclear fission occurs when a large, unstable atomic nucleus (such as Uranium-235) is split into smaller, lighter nuclei by a stray neutron, releasing massive amounts of energy and radioactive waste.
- Step 2 (Fusion Mechanics): Nuclear fusion occurs when light atomic nuclei (such as isotopes of Hydrogen) are forced together under extreme heat and pressure to form a heavier nucleus (like Helium), powering stars without generating long-lived waste.
- Incorrect Options:
- Fission joins light nuclei; fusion splits heavy nuclei is incorrect because it completely reverses the true physical definitions of both processes.
- Fission requires higher temperature than fusion is incorrect because fusion requires extreme temperatures exceeding 100 million degrees Celsius to overcome electrostatic repulsion, whereas fission can occur at room temperature.
- Fission produces no radioactive waste is incorrect because fission processes inevitably split heavy atoms into highly radioactive isotopes that require strict long-term containment.
Constable Model Past paper 2025 PDF Every Day Science
A.
Troposphere
B.
Stratosphere
C.
Mesosphere
D.
Thermosphere.
Correct answer is:
D. Thermosphere.
Explanation:
The correct answer is Thermosphere. because its name directly stems from the Greek word 'therme' (meaning heat), driven by intense solar radiation absorption.
- Step 1 (Thermal Mechanics): Located above the mesosphere, the thermosphere absorbs highly energetic ultraviolet and X-ray radiation from the Sun, causing gases to reach extreme temperatures up to 1,500°C (2,700°F).
- Step 2 (Density Factor): Despite these massive atomic kinetic temperatures, the air is so incredibly thin and close to a vacuum that it contains insufficient gas molecules to transfer heat to passing objects.
- Incorrect Options:
- Troposphere is incorrect because it is the lowest, densest atmospheric layer where weather systems occur, characterized by temperatures that decrease with altitude.
- Stratosphere is incorrect because it is the stable middle layer containing the protective ozone layer, experiencing a milder warming trend from UV absorption.
- Mesosphere is incorrect because it is the coldest layer of the entire Earth's atmosphere, where temperatures drop down to nearly -90°C.
Constable Model Past paper 2025 PDF Every Day Science
A.
Carbon dioxide
B.
Chlorofluorocarbons (CFCs).
C.
Nitrogen gas
D.
Methane
Correct answer is:
B. Chlorofluorocarbons (CFCs).
Explanation:
The correct answer is Chlorofluorocarbons (CFCs). because these industrial compounds break down under solar radiation to release destructive chlorine radicals.
- Step 1 (Chemical Dissociation): When non-reactive CFC compounds drift into the stratosphere, they are hit by harsh ultraviolet (UV) light, which breaks their molecular bonds and frees atomic chlorine.
- Step 2 (Catalytic Cycle): A single free chlorine atom acts as a relentless catalyst, systematically breaking apart up to 100,000 vital ozone (O₃) molecules before turning inert.
- Incorrect Options:
- Carbon dioxide is incorrect because CO₂ acts as a prominent greenhouse gas that traps heat in the lower troposphere rather than destroying ozone.
- Nitrogen gas is incorrect because N₂ is an inert, non-destructive element that makes up the vast majority (78%) of Earth's natural atmosphere.
- Methane is incorrect because while CH₄ influences global warming as a potent greenhouse gas, it does not serve as the primary chemical driver of the stratospheric ozone hole.
Constable Model Past paper 2025 PDF Every Day Science
