100+ Free BARC OCES/DGFS Practice Questions

Pass your BARC Scientific Officer (OCES/DGFS) Online Screening Examination exam on the first try — instant access, no signup required.

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Sample BARC OCES/DGFS Practice Questions

Try these sample questions to test your BARC OCES/DGFS exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which particle has the highest ionising power per unit path length among the common types of nuclear radiation?

A.Gamma photon

B.Beta particle

C.Alpha particle

D.Neutron (thermal)

Explanation: Alpha particles are doubly charged helium nuclei with large mass; they interact strongly with matter and deposit energy over a very short range, giving the highest linear energy transfer among alpha, beta, and gamma. This is why alpha sources are hazardous if ingested but are stopped by a sheet of paper or skin.

2In a nuclear fission chain reaction in a thermal reactor, which material most commonly serves as the moderator?

A.Boron

B.Heavy water or light water

C.Cadmium

D.Lead

Explanation: Moderators slow fast fission neutrons to thermal energies (~0.025 eV) to increase the fission cross-section of U-235. Light water (in PWR/BWR) and heavy water (in PHWR/CANDU-type designs used in India) are standard moderators. BARC training covers PHWR operation extensively.

3The SI unit of radioactivity (activity) is:

A.Gray (Gy)

B.Sievert (Sv)

C.Becquerel (Bq)

D.Curie (Ci)

Explanation: Activity measures disintegrations per second; the SI unit is the becquerel (1 Bq = 1 decay/s). The curie is a legacy unit (3.7×10¹⁰ Bq). Gray measures absorbed dose; sievert measures equivalent dose.

4India's indigenous Pressurised Heavy Water Reactors (PHWRs) use which combination of fuel and moderator/coolant?

A.Enriched U-235 fuel with light water moderator

B.Natural uranium fuel with heavy water moderator and coolant

C.MOX fuel with graphite moderator

D.Thorium fuel with sodium coolant

Explanation: Indian PHWRs (e.g., Rajasthan, Kakrapar, Narora stations) use natural uranium oxide fuel and heavy water (D₂O) as both moderator and coolant. This design avoids enrichment for the initial fuel load and is central to India's nuclear power programme under DAE.

5What is the primary purpose of control rods in a thermal nuclear reactor?

A.Increase neutron flux to raise power

B.Absorb excess neutrons to regulate or shut down the chain reaction

C.Convert thermal neutrons to fast neutrons

D.Shield operators from gamma radiation

Explanation: Control rods contain neutron absorbers (e.g., cadmium, boron, hafnium). Inserting them increases neutron absorption and reduces reactivity; full insertion shuts the reactor down. This is fundamental reactor operation taught at BARC Training Schools.

6According to Einstein's mass-energy relation used in nuclear reactions, energy E is related to mass m by:

A.E = mc

B.E = mc²

C.E = ½mv²

D.E = mgh

Explanation: Nuclear binding energy and fission energy release are understood through E = mc². The mass defect of a nucleus converts to energy when nucleons bind or when fission fragments separate. This relation underpins energy accounting in reactor physics.

7Which isotope is most commonly used as fuel in Indian PHWRs?

A.U-238 only

B.Natural uranium (mostly U-238 with ~0.7% U-235)

C.Pu-239 only

D.Th-232 without conversion

Explanation: Natural uranium contains about 0.72% U-235 and the balance U-238. PHWRs use this without initial enrichment; U-238 converts to plutonium in situ, supporting India's three-stage nuclear programme envisioned by Homi Bhabha.

8Half-life is defined as the time required for:

A.Half the mass of a radioactive sample to convert to energy

B.Half the radioactive nuclei in a sample to decay

C.Radiation intensity to double

D.A reactor to reach criticality

Explanation: Half-life (t½) is the time for half of a large number of identical radioactive nuclei to undergo decay statistically. It is an intrinsic property of each radionuclide and appears in decay heat, waste management, and radiopharmaceutical dosing.

9In nuclear fission of U-235 by a thermal neutron, the typical outcome includes:

A.Fusion of two light nuclei

B.Only gamma emission with no neutron release

C.Complete conversion of mass to a single particle

D.Two fission fragments, neutrons, and energy release

Explanation: Thermal-neutron fission of U-235 produces two medium-mass fission fragments, 2–3 neutrons on average, and ~200 MeV of energy (mostly kinetic energy of fragments and prompt gamma). Sustaining a chain reaction requires a net positive neutron balance after leakage and absorption.

10Which organisation is the parent department of Bhabha Atomic Research Centre (BARC)?

A.Ministry of Power

B.Department of Atomic Energy (DAE)

C.Department of Science and Technology

D.Atomic Energy Regulatory Board (AERB)

Explanation: BARC is a premier DAE unit headquartered at Trombay, Mumbai. DAE oversees nuclear research, power (via NPCIL), fuel cycle entities, and training programmes including OCES/DGFS at BARC Training Schools.

About the BARC OCES/DGFS Exam

The BARC OCES/DGFS online screening recruits Scientific Officers into India's nuclear programme. Successful candidates train at BARC Training Schools and join DAE units (BARC, NPCIL, IGCAR, etc.) as Scientific Officer 'C' (Level 10, ₹56,100 basic under 7th CPC). The CBT tests deep discipline knowledge comparable to GATE difficulty with negative marking — candidates may also screen via GATE score.

Assessment

OCES/DGFS-2026 screening: single online CBT of 100 objective MCQs in 120 minutes (+3 correct, −1 wrong, 0 skipped; 300 marks). Questions match the candidate's selected discipline at B.E./B.Tech. (engineering codes 21–28) or M.Sc. (science codes 41, 42, 43, 45, 46) level. Alternative screening via valid GATE score in the eligible paper. Shortlisted candidates attend selection interviews; selected trainees join OCES-2026 (1-year orientation) or DGFS-2026 (2-year IIT M.Tech. fellowship) at BARC Training Schools.

Time Limit

120 minutes (2 hours) for 100 MCQs

Passing Score

No fixed qualifying percentage published; discipline-wise CBT cutoffs (out of 300) and GATE cutoffs are announced after screening for interview shortlisting

Exam Fee

₹500 non-refundable + bank charges for male General/OBC/Dep-1984/Dom-Kashmir applicants; exempt for female, transgender, SC/ST, DODPKIA, PwBD (40%+) (Bhabha Atomic Research Centre (BARC), Department of Atomic Energy (DAE))

BARC OCES/DGFS Exam Content Outline

18%

Nuclear Science & Radiation

Reactor physics, radiation, shielding, fuel cycle, PHWR, DAE/AERB — cross-cutting nuclear fundamentals

12%

Engineering Mathematics

Calculus, linear algebra, ODEs, probability, numerical methods, transforms

12%

Physics Fundamentals

Mechanics, thermodynamics, electromagnetism, optics, modern physics

10%

Chemistry Fundamentals

Atomic structure, bonding, kinetics, electrochemistry, coordination chemistry

10%

Mechanical & Thermal Engineering

Thermodynamics, fluid mechanics, strength of materials, machine design

10%

Electrical & Electronics

AC circuits, machines, network theorems, semiconductors, 3-phase systems

Civil & Environmental

Soil mechanics, concrete, hydraulics, wastewater, structural analysis

Instrumentation & Control

Sensors, 4–20 mA loops, PID, transfer functions, stability

Computer Science

Algorithms, OS, DBMS, networks, digital logic

DAE/BARC Exam Logistics

Official pattern, fees, disciplines, GATE alternative, posting details

How to Pass the BARC OCES/DGFS Exam

What You Need to Know

Passing score: No fixed qualifying percentage published; discipline-wise CBT cutoffs (out of 300) and GATE cutoffs are announced after screening for interview shortlisting
Assessment: OCES/DGFS-2026 screening: single online CBT of 100 objective MCQs in 120 minutes (+3 correct, −1 wrong, 0 skipped; 300 marks). Questions match the candidate's selected discipline at B.E./B.Tech. (engineering codes 21–28) or M.Sc. (science codes 41, 42, 43, 45, 46) level. Alternative screening via valid GATE score in the eligible paper. Shortlisted candidates attend selection interviews; selected trainees join OCES-2026 (1-year orientation) or DGFS-2026 (2-year IIT M.Tech. fellowship) at BARC Training Schools.
Time limit: 120 minutes (2 hours) for 100 MCQs
Exam fee: ₹500 non-refundable + bank charges for male General/OBC/Dep-1984/Dom-Kashmir applicants; exempt for female, transgender, SC/ST, DODPKIA, PwBD (40%+)

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

BARC OCES/DGFS Study Tips from Top Performers

1Revise your discipline syllabus at GATE-level depth — BARC CBT difficulty is comparable to GATE 2-mark questions with −1 negative marking, so accuracy matters as much as speed.

2Practice 100-question timed mocks in 120 minutes with selective guessing; unattempted (0) beats wrong (−1) when unsure.

3Study nuclear fundamentals (reactor types, radiation safety, DAE structure) regardless of discipline — BARC interviews and training assume atomic-energy context.

4If eligible, register for both the online CBT and GATE screening; historical cutoffs vary widely by discipline (CBT out of 300).

Frequently Asked Questions

What is the BARC OCES/DGFS online exam pattern?

Per the OCES/DGFS-2026 information brochure: 100 MCQs in 120 minutes, +3 marks per correct answer, −1 per wrong answer, 0 for unattempted (300 marks total). Questions are discipline-specific at B.E./B.Tech. or M.Sc. level.

Can I skip the BARC online exam if I have a GATE score?

GATE is an alternative screening channel, not a mandatory exemption. The brochure advises candidates to use both routes to maximise interview shortlist chances. Valid GATE years and eligible papers are listed per discipline in Table-1.

What is the BARC OCES application fee?

Male General/OBC/Dep-1984/Dom-Kashmir applicants pay ₹500 non-refundable plus bank charges. Female, transgender, SC/ST, DODPKIA, and PwBD (40%+) candidates are fee-exempt per Table-5 of the 2026 brochure.

How does this 100-question practice bank relate to the real exam?

The official CBT is 100% discipline-specific. This bank samples cross-disciplinary STEM and nuclear topics common across BARC training backgrounds. For exam prep, prioritise your chosen discipline syllabus (ME, EE, CS, PH, CY, etc.) at GATE-equivalent depth.