CrackTarget UPSC Scientist-B Atmospheric Sciences 2026 GAT question paper: original PDF, all 100 questions solved, 300 marks, Series A.

UPSC Scientist-B Atmospheric Sciences 2026 Question Paper PDF: All 100 Questions Solved

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CRACKTARGET • SOLVED RECRUITMENT PAPER • SERIES A

Scientist-B Atmospheric Sciences 2026: practise, understand, revise

Download the original GAT paper and work through all 100 questions with clear reasoning, calculations and explanations. Advertisement 05/2026 • Vacancy 26050512623 • 7 posts.

Important note: this is a common UPSC GAT question paper

This question paper is common to the following 12 recruitment posts under UPSC Advertisement No. 05/2026, covering 72 vacancies: 46 Scientist-B vacancies in the Ministry of Earth Sciences and 26 Assistant Director Grade-I/Grade-II (IEDS) vacancies in the Ministry of Micro, Small and Medium Enterprises (MSME).

UPSC lists the question paper against each recruitment entry below, with 12 October 2026 (12/10/2026) as the date of upload. The links below open the corresponding official UPSC PDFs.

Scientist-B — Ministry of Earth Sciences

Recruitment post and vacanciesVacancy number and official UPSC paper
Scientist-B (Atmospheric Sciences)
7 posts
26050512623
Download official PDF
Scientist-B (General Meteorology)
30 posts
26050513623
Download official PDF
Scientist-B (Instrumentation)
9 posts
26050514623
Download official PDF

Assistant Director Grade-I / Grade-II (IEDS) — Ministry of MSME

Recruitment post and vacanciesVacancy number and official UPSC paper
Assistant Director Grade-II (IEDS) (Leather & Footwear)
4 posts
26050526623
Download official PDF
Assistant Director Grade-II (IEDS) (Hosiery)
4 posts
26050524623
Download official PDF
Assistant Director Grade-II (IEDS) (Food)
4 posts
26050522623
Download official PDF
Assistant Director Grade-II (IEDS) (Chemical)
3 posts
26050520623
Download official PDF
Assistant Director Grade-I (IEDS) (Metal Finishing)
1 post
26050527623
Download official PDF
Assistant Director Grade-I (IEDS) (Leather & Footwear)
3 posts
26050525623
Download official PDF
Assistant Director Grade-I (IEDS) (Hosiery)
2 posts
26050523623
Download official PDF
Assistant Director Grade-I (IEDS) (Food)
3 posts
26050521623
Download official PDF
Assistant Director Grade-I (IEDS) (Chemical)
2 posts
26050519623
Download official PDF

How to use these solutions: All 100 question-wise explanations on this page apply to the common GAT paper for the recruitments listed above. The answer letters follow Series A, T.B.C. HCLM-B-NPT; match the question text and option order before using them for another booklet series.

Looking for the UPSC Scientist B Atmospheric Sciences 2026 question paper PDF with solutions? This CrackTarget study post brings together the original Series A booklet, a question-wise explanatory answer key and worked solutions for the complete paper. It is relevant to the Scientist-B (Atmospheric Sciences) recruitment in the India Meteorological Department, Ministry of Earth Sciences, under Vacancy No. 26050512623. The cover identifies it as the shared GAT combined recruitment paper for Assistant Director Grade I/II and Scientist-B.

Answer-key status: These are CrackTarget’s independently prepared educational solutions, not a UPSC-issued official answer key. The original question paper is supplied unchanged. Stems below are lightly condensed for readability; question numbers and option order follow Series A, T.B.C. HCLM-B-NPT. Other booklet series must be matched by question text, not by number alone. Reviewed on 25 October 2026.

Paper overview and marking scheme

ItemDetails
RecruitmentScientist-B (Atmospheric Sciences), IMD, Ministry of Earth Sciences
Advertisement / vacancy05/2026 / 26050512623
Posts7
Test date11 October 2026, afternoon; cover annotation
Paper / bookletGAT / Series A / HCLM-B-NPT
Questions / maximum marks100 / 300
Duration2 hours
Marking from booklet instructions+3 for a correct response; −1 for an incorrect response; 0 for an unattempted item
Original PDF20 scanned pages; about 14.5 MiB; questions on booklet pages 2–16

All 100 questions carry equal marks. Since the total is 300, each correct answer carries 3 marks; the stated one-third penalty therefore deducts 1 mark for a wrong answer. Multiple marked responses are treated as incorrect. For self-evaluation, use score = 3 × correct − wrong, subject to any UPSC final-key or question-deletion decision.

Download the original UPSC question paper

The download preserves the uploaded scan, including the instructions, all options and rough-work pages. Use it for a timed 120-minute attempt before opening the explanations below. The test provides an average of 72 seconds per question; individual questions will require different amounts of time.

Official reference: UPSC recruitment-test question-paper archive. Check the UPSC recruitment-test answer-key section separately for any official release. This post does not claim that an official answer key has been issued.

Jump to the section you need

Quick answer key: UPSC Scientist-B GAT 2026, Series A

Letters refer to the original Series A option order. Review means that the exact calculation has no matching printed choice. An asterisk marks a material interpretation or model note explained under that question. Click any question number for its worked solution.

Questions 1–20

QAnswerQAnswer
1A11A
2C12A
3C13A
4B14B
5B15B
6C16B
7A17A
8B18D
9C19C
10B20B

Questions 21–40

QAnswerQAnswer
21A31C
22C32C
23B33D
24D34D
25C35C
26B36B
27D37A
28B38C
29C39D
30B40C*

Questions 41–60

QAnswerQAnswer
41D51A
42B52A
43A53D
44B54A*
45D*55A
46D56C
47B57C
48Review*58A
49A59C
50D60D

Questions 61–80

QAnswerQAnswer
61A71C
62B72D
63C73D
64D74B
65C75C
66A*76D
67B77A
68A78B
69C79C
70D80A*

Questions 81–100

QAnswerQAnswer
81C91B
82A92B
83D93D*
84A94C
85A95C
86C96C
87C97D
88B98C
89C99C
90B100B

Before scoring: Q48 has no exact matching option. Q40, Q45, Q54, Q66, Q80 and Q93 include interpretation or modelling notes. These notes explain what the selected option assumes; they are not announcements of an official objection outcome.

Q1–Q8: Environment, ecology and mechanics

Q1. Greenwashing

What is disinformation used by an organisation to present an environmentally responsible public image called?

  • (A) Greenwashing
  • (B) Imaging
  • (C) Ecocriticism
  • (D) Bootlegging
View answer and explanation

Answer: (A) Greenwashing

Greenwashing means creating a misleading impression that an organisation, product or activity is environmentally responsible. The key clue is the gap between the public claim and the underlying environmental performance. A claim may use vague language, selective disclosure or unsupported labels. Ecocriticism is an approach to studying literature and the environment; it is not the marketing practice described here. Remember: a green claim needs evidence, not merely green branding.

Source: United Nations: greenwashing

Q2. Energy source for photosynthesis

The energy processes in photosynthesis depend on which of the following?

  • (A) Universal constant
  • (B) Velocity of light
  • (C) Photons of solar radiation
  • (D) Temperature
View answer and explanation

Answer: (C) Photons of solar radiation

Chlorophyll and associated pigments absorb photons. The absorbed light energy drives the light-dependent reactions, producing ATP and reducing power that support carbon fixation. Temperature affects the rate of enzyme-controlled reactions, but it is not the original energy input. The speed of light is relevant to the photon-energy relationship E = hc/λ; the actual energy arriving at the photosynthetic system is carried by photons.

Q3. Rotational kinetic energy

What is the kinetic energy of a rotating flywheel?

  • (A) Moment of inertia multiplied by half the angular velocity
  • (B) One-fourth of the angular velocity
  • (C) Half the product of moment of inertia and the square of angular velocity
  • (D) Product of mass and concentrated radius
View answer and explanation

Answer: (C) K = ½Iω²

For a small mass element, kinetic energy is ½mv². In rotation, v = rω, so summing over all mass elements gives K = ½(Σmr²)ω² = ½Iω². Moment of inertia plays the role that mass plays in translational kinetic energy. A common error is to forget the square on angular velocity. Doubling ω, while I remains fixed, makes the stored energy four times as large.

Q4. US Soil Taxonomy

Which soil-order description is incorrect?

  • (A) Histosols: organic soils in bogs and swamps
  • (B) Inceptisols: old soils often found in dry conditions
  • (C) Entisols: little or no horizon development, including recent deposits
  • (D) Vertisols: clay soils that swell when wet and crack when dry
View answer and explanation

Answer: (B) The description of Inceptisols is incorrect

Inceptisols show relatively early or weak soil-profile development. Calling them old soils typical of dry conditions reverses their defining developmental character. Entisols have still less horizon development; Histosols contain substantial organic material; Vertisols have pronounced shrink-swell behaviour associated with clay. In soil-taxonomy questions, identify the diagnostic property of the order rather than assigning every order to a single climate.

Source: USDA NRCS: Inceptisols

Q5. Environmental institutions

Which institution-location pair is incorrect?

  • (A) Wildlife Institute of India — Dehradun
  • (B) Kalpavriksh — Belgaum
  • (C) Salim Ali Centre for Ornithology and Natural History — Coimbatore
  • (D) World Wide Fund for Nature — New Delhi
View answer and explanation

Answer: (B) Kalpavriksh — Belgaum

Kalpavriksh’s published contact address is in Pune, Maharashtra, making the Belgaum pairing incorrect. The other listed locations correspond to the institutions named in the question. Institution-location MCQs are best revised as matched pairs: organisation, main location and field of work. Do not confuse the location of an institution’s project, field camp or occasional event with its principal contact location.

Source: Kalpavriksh: official contact address

Q6. Meaning of ecology

Ecology primarily studies the relationship between which entities?

  • (A) Plants and animals only
  • (B) Soil and water only
  • (C) Living organisms and their environment
  • (D) Atmosphere and deserts only
View answer and explanation

Answer: (C) Living organisms and their environment

Ecology examines interactions among organisms and between organisms and their physical surroundings. It therefore includes biotic relationships, such as competition and predation, and abiotic influences, such as temperature, water and soil. Each of the other options selects only a narrow part of this wider field. The phrase “organisms and environment” is the most complete description.

Q7. Hazardous-waste characteristics

Which is not a separately named criterion in the standard four-characteristic classification of hazardous waste?

  • (A) Lethality
  • (B) Flammability
  • (C) Corrosivity
  • (D) Reactivity
View answer and explanation

Answer: (A) Lethality

The familiar four characteristics are ignitability, corrosivity, reactivity and toxicity. Flammability corresponds to ignitability in the choices. Lethality can describe a toxic effect or enter toxicity assessment, but it is not a separate heading in this four-characteristic framework. This is a terminology question: the answer does not mean that a lethal waste is harmless or cannot be hazardous.

Source: US EPA: hazardous-waste characteristics

Q8. Acid rain

Which substance accounts for the stated 60–70% share of acidity in the conventional acid-rain description?

  • (A) HCl
  • (B) H₂SO₄
  • (C) NH₃
  • (D) HNO₃
View answer and explanation

Answer: (B) Sulphuric acid, H₂SO₄

Sulphur dioxide can be oxidised in the atmosphere and contribute to sulphuric acid formation. Nitrogen oxides contribute nitric acid, the other major acid-rain component. Ammonia is basic and can partly neutralise acids. The percentage in the question is a conventional textbook description, not a universal proportion: the sulphuric-to-nitric-acid contribution varies with emissions, location and atmospheric chemistry. The intended choice is H₂SO₄.

Back to the answer key • Section navigation

Q9–Q16: Production and operations management

Q9. Modern cost leadership

Which action best represents a modern approach to cost leadership?

  • (A) Reduce employee-training expenditure
  • (B) Defer machine replacement
  • (C) Eliminate only non-value-adding activities
  • (D) Reduce vendor-development activities
View answer and explanation

Answer: (C) Eliminate non-value-adding activities

Sustainable cost leadership removes avoidable waste while protecting activities that deliver customer value. Cutting training, delaying necessary replacement or weakening suppliers may reduce immediate spending but increase defects, downtime or lifecycle cost. Value analysis asks whether an activity contributes to the required function and customer benefit. The best option therefore targets non-value-adding work rather than applying indiscriminate spending cuts.

Q10. HMMS model

Which mathematical functions are used to represent different costs in the Holt–Modigliani–Muth–Simon model?

  • (A) Linear
  • (B) Quadratic
  • (C) Exponential
  • (D) Logarithmic
View answer and explanation

Answer: (B) Quadratic functions

The classical HMMS aggregate-planning model approximates relevant costs with quadratic functions. These costs can include inventory-related and workforce-adjustment costs. Optimising a quadratic objective can produce linear decision rules, which explains a common trap: the decision rule may be linear even though the cost functions are quadratic. The question asks specifically about the representation of costs.

Source: INFORMS: quadratic production-inventory planning

Q11. Make-or-buy analysis

Which is not a standard approach to a make-or-buy decision?

  • (A) Sales revenue analysis
  • (B) Simple cost analysis
  • (C) Economic analysis
  • (D) Break-even analysis
View answer and explanation

Answer: (A) Sales revenue analysis

A make-or-buy choice compares the relevant cost and implications of internal production against external purchase. Simple cost comparison, broader economic analysis and break-even analysis can all help. Sales revenue alone usually does not distinguish the alternatives when the same final product is sold in either case. Capacity, quality, supplier reliability and opportunity cost still matter; the answer concerns the named analytical approaches, not a claim that revenue is never relevant.

Q12. Cumulative delivery schedule

A cumulative delivery schedule graph is associated with which technique?

  • (A) Line of Balance
  • (B) Assembly Line Balancing
  • (C) PERT
  • (D) Six Sigma
View answer and explanation

Answer: (A) Line of Balance

Line of Balance links planned deliveries of repetitive units with progress at key production or completion stages. A cumulative delivery schedule shows how many completed units are required by successive dates. Assembly-line balancing allocates tasks among workstations; PERT studies activity networks and project timing; Six Sigma focuses on variation and defects. The word “cumulative delivery” points to Line of Balance.

Q13. Economic order quantity

Annual demand is 600 units, ordering cost ₹30 per order and carrying cost ₹10 per unit per year. Find EOQ.

  • (A) 60 units
  • (B) 43 units
  • (C) 14 units
  • (D) 20 units
View answer and explanation

Answer: (A) 60 units

Use EOQ = √(2DS/H), where D is annual demand, S is ordering cost per order and H is annual holding cost per unit. Substitution gives √[(2 × 600 × 30)/10] = √3600 = 60 units. At this quantity the basic model balances annual ordering and holding costs. Check the units: an annual demand requires a holding cost expressed for the same annual period.

Q14. Aggregate plan and MPS

What is the relationship between aggregate planning and the master production schedule?

  • (A) MPS comes before aggregate planning
  • (B) Aggregate planning precedes MPS
  • (C) Both must be developed simultaneously
  • (D) There is no relationship
View answer and explanation

Answer: (B) Aggregate planning precedes MPS

An aggregate plan sets a broad output, workforce and inventory framework, often for product families. The master production schedule disaggregates that framework into specific end items, quantities and dates. Thus the logical planning sequence is aggregate plan followed by MPS, which then supports more detailed material and capacity planning. Actual organisations use feedback between levels, but this does not reverse the basic hierarchy.

Q15. CRAFT objective

What is the principal objective of the Computerized Relative Allocation of Facilities Technique?

  • (A) Maximise material-handling costs
  • (B) Minimise material-handling costs
  • (C) Maximise machine utilisation
  • (D) Minimise labour costs
View answer and explanation

Answer: (B) Minimise material-handling costs

CRAFT improves a facility layout by evaluating exchanges of departments or activity areas. Its objective commonly reflects material flow multiplied by travel distance and handling cost. Placing strongly connected departments closer together can reduce total handling cost. Labour cost and utilisation may be important to management, but they are not the specific objective identified by CRAFT in this question.

Q16. Decision levels

Product improvement through value analysis is an example of which type of decision?

  • (A) Strategic
  • (B) Tactical
  • (C) Operational
  • (D) Policy
View answer and explanation

Answer: (B) Tactical decision

In the standard production-management classification, improving an existing product through value analysis is a tactical decision. It translates broad competitive objectives into a practical improvement programme. Strategic decisions define major long-term directions, such as a new plant or product domain; operational decisions concern routine execution and daily scheduling. The focus here is an improvement initiative within an existing operating framework.

Back to the answer key • Section navigation

Q17–Q24: Materials science and manufacturing

Q17. BCC atomic packing factor

What is the atomic packing factor of a body-centred cubic structure?

  • (A) 0.68
  • (B) 0.74
  • (C) 0.95
  • (D) 1.00
View answer and explanation

Answer: (A) Approximately 0.68

A BCC unit cell contains two atoms effectively. The body diagonal gives √3a = 4r. Therefore APF = [2 × (4πr³/3)]/a³ = π√3/8 ≈ 0.680. FCC and ideal HCP structures have an APF of about 0.74. An APF of 1 would mean no unoccupied space, which is not achieved by these arrangements of equal spheres.

Q18. Slip casting

A clay-water slurry is poured into a porous mould; water absorption creates a clay layer on the mould wall. Identify the process.

  • (A) Die casting
  • (B) Centrifugal casting
  • (C) Investment casting
  • (D) Slip casting
View answer and explanation

Answer: (D) Slip casting

The clay suspension is called a slip. A porous mould absorbs liquid, leaving a consolidated layer of clay particles against its wall. Excess slip may be drained to produce a hollow component. Die casting involves forcing material into a die, centrifugal casting uses rotational effects, and investment casting uses an expendable pattern. The slurry-plus-porous-mould description is characteristic of slip casting.

Q19. Specific modulus

Which material has the highest specific modulus among the listed choices?

  • (A) Steel
  • (B) Silica
  • (C) Alumina
  • (D) Cement
View answer and explanation

Answer: (C) Alumina

Specific modulus is elastic modulus divided by density, E/ρ. It measures stiffness per unit mass, which matters in lightweight structures. Typical dense alumina combines a high elastic modulus with substantially lower density than steel, giving a higher specific modulus than the listed alternatives. Do not select steel solely because it is strong: strength, modulus and modulus-to-density ratio are different properties. Exact values depend on grade and porosity.

Q20. Cold working

Which factor is important in shaping metals by cold working?

  • (A) Recrystallisation
  • (B) Strain hardening
  • (C) Thermal expansion
  • (D) Solid-solution strength
View answer and explanation

Answer: (B) Strain hardening

Cold working plastically deforms metal below its recrystallisation temperature. Dislocation density increases, and dislocations obstruct one another, increasing strength and hardness while generally reducing ductility. This is strain hardening, also called work hardening. Recrystallisation can later restore ductility during appropriate heating, but it is not the strengthening mechanism that characterises cold deformation.

Q21. Modulus of rupture

Which listed material typically has the highest modulus of rupture?

  • (A) Alumina
  • (B) Borosilicate glass
  • (C) Steatite
  • (D) Mullite
View answer and explanation

Answer: (A) Alumina

Modulus of rupture is a flexural-strength measure: the maximum bending stress calculated at fracture in a specified test. In standard comparisons of these engineering ceramics and glass, dense alumina has the highest typical flexural strength among the choices. It should not be confused with Young’s modulus, which measures stiffness. Ceramic strength depends strongly on flaws, porosity, specimen preparation and test conditions, so this is a typical-material comparison rather than an absolute ranking of every commercial grade.

Q22. Quenching steel

Which transformation occurs when steel is rapidly quenched from the austenitic condition?

  • (A) Pearlitic
  • (B) Bainitic
  • (C) Martensitic
  • (D) Spheroidite
View answer and explanation

Answer: (C) Martensitic transformation

Rapid cooling can suppress the diffusion-controlled formation of pearlite and allow austenite to transform into martensite. This is a diffusionless transformation involving a coordinated change in crystal structure. Carbon trapped in the transformed structure contributes to high hardness and internal strain. The usual exam association is rapid quenching → martensite; the actual structure also depends on composition, cooling rate and section size.

Q23. Bonding and electronegativity

Which bonding type is associated with a small electronegativity difference between the bonded atoms?

  • (A) Metallic
  • (B) Covalent
  • (C) Ionic
  • (D) Secondary
View answer and explanation

Answer: (B) Covalent bonding

When electronegativities are similar, neither atom overwhelmingly attracts the bonding electrons, so electron sharing is favoured. This is the basic description of covalent bonding. A large electronegativity difference favours ionic character. Metallic bonding is described by delocalised electrons in a metal, while secondary bonding includes weaker interactions between atoms or molecules. The clue is the small difference and resulting sharing tendency.

Q24. Mass percentage in Cu₅Si

Given atomic weights Cu = 63.54 and Si = 28.09, find the mass percentage of copper in Cu₅Si.

  • (A) 8.12%
  • (B) 30.66%
  • (C) 69.34%
  • (D) 91.88%
View answer and explanation

Answer: (D) 91.88%

One formula unit contains five copper atoms and one silicon atom. Copper contributes 5 × 63.54 = 317.70 mass units; the total is 317.70 + 28.09 = 345.79. Hence copper percentage = (317.70/345.79) × 100 ≈ 91.88%. The subscript 5 is essential. Using a 1:1 Cu:Si ratio would solve a different chemical formula.

Back to the answer key • Section navigation

Q25–Q32: Computers, networks and satellite communication

Q25. BIOS storage

Where is the BIOS stored, in the conventional classification used by this question?

  • (A) RAM
  • (B) Cache memory
  • (C) ROM
  • (D) Hard disk
View answer and explanation

Answer: (C) ROM

The BIOS must retain its firmware when power is switched off, so the textbook answer is non-volatile ROM. Modern motherboards generally use rewritable flash memory for firmware updates, but flash is still non-volatile firmware storage. Ordinary RAM and cache lose their contents without power, and the operating-system disk is not the conventional location of motherboard BIOS firmware.

Q26. Wi-Fi standard

Wi-Fi products are based on which IEEE standards family?

  • (A) 802.3
  • (B) 802.11
  • (C) 802.15
  • (D) 802.16
View answer and explanation

Answer: (B) IEEE 802.11

IEEE 802.11 specifies wireless local-area networking, the standards family underlying Wi-Fi. IEEE 802.3 is associated with Ethernet, 802.15 with wireless personal-area networking, and 802.16 with broadband wireless metropolitan-area networking. New Wi-Fi generations add or update capabilities within the 802.11 family; they do not change the basic family number asked here.

Q27. Wardriving

What is searching for unsecured Wi-Fi networks while driving around called?

  • (A) Phishing
  • (B) Packet switching
  • (C) Spoofing
  • (D) War driving
View answer and explanation

Answer: (D) Wardriving

Wardriving involves moving through an area, traditionally in a vehicle, while detecting wireless networks. In this question the search is specifically for unsecured Wi-Fi. Phishing deceives users into revealing information; spoofing impersonates an identity or address; packet switching is a method of transmitting data. Recognise the terminology without confusing network discovery with those separate activities.

Q28. Image pixels

Increasing the number of pixels in a digital image primarily improves which property?

  • (A) Brightness
  • (B) Resolution
  • (C) Contrast
  • (D) Refresh rate
View answer and explanation

Answer: (B) Resolution

A larger pixel grid can represent finer spatial detail, which is the idea of resolution in this question. Brightness concerns intensity, contrast concerns differences between tones, and refresh rate concerns display updates over time. More pixels do not automatically make a poor source image sharper: optics, focus, sensor quality and processing also matter. Nevertheless, resolution is the property directly associated with pixel count.

Q29. Packet switching

Packet switching shares network resources on which basis?

  • (A) Dedicated
  • (B) Fixed allocation
  • (C) Demand
  • (D) Permanent
View answer and explanation

Answer: (C) Demand basis

In packet-switched networks, traffic is divided into packets that use shared links as needed. Resources are statistically multiplexed rather than permanently reserved for one communication. This makes packet switching suitable for bursty data traffic. A dedicated end-to-end resource reservation is more characteristic of the basic circuit-switching model. Demand-based sharing can also create queues when packets compete for a busy link.

Q30. Spectrum symmetry

What symmetry does the spectrum of a real-valued signal exhibit?

  • (A) Circular
  • (B) Conjugate
  • (C) Time
  • (D) Linear
View answer and explanation

Answer: (B) Conjugate symmetry

For a real-valued time signal x(t), its Fourier transform satisfies X(−f) = X*(f), where the star denotes complex conjugation. Consequently, the magnitude spectrum is even and the phase spectrum is odd where phase is well defined. A real time-domain signal does not have to be even in time. Conjugate symmetry is therefore the general frequency-domain property.

Q31. Geostationary altitude

Approximately how high above the equator is a geostationary satellite?

  • (A) 2,230 miles
  • (B) 10,000 miles
  • (C) 22,300 miles
  • (D) 42,300 miles
View answer and explanation

Answer: (C) 22,300 miles

A geostationary satellite orbits at an altitude of roughly 35,786 km, or about 22,236 miles, conventionally rounded to 22,300 miles in this option. Its orbital period matches Earth’s sidereal rotation, and the orbit is circular and equatorial. Distinguish altitude above Earth’s surface from distance measured from Earth’s centre, which is about 42,164 km.

Q32. Ku-band satellite links

Which uplink/downlink pair is typically associated with Ku-band satellite communication?

  • (A) 6 GHz / 4 GHz
  • (B) 8 GHz / 6 GHz
  • (C) 14 GHz / 12 GHz
  • (D) 30 GHz / 20 GHz
View answer and explanation

Answer: (C) Uplink about 14 GHz; downlink about 12 GHz

The conventional Ku-band pairing is approximately 14 GHz for uplink and 12 GHz for downlink. The familiar C-band pairing is 6/4 GHz, and the common Ka-band pairing is 30/20 GHz. Actual assigned frequency ranges depend on region and service. The question seeks the standard approximate band pairing, not one universal operating frequency for every satellite.

Back to the answer key • Section navigation

Q33–Q40: Engineering ethics, safety and sustainability

Q33. Core human values

Which is not included in the conventional five-core-human-values list?

  • (A) Right conduct
  • (B) Truth
  • (C) Non-violence
  • (D) Simplicity
View answer and explanation

Answer: (D) Simplicity

The commonly taught five values in this framework are truth, right conduct, peace, love and non-violence. Simplicity may be a valuable personal quality, but it is not one of these five named headings. Such questions test a specified educational classification rather than judging whether an excluded quality is ethically undesirable. Truth, right conduct and non-violence are all present in the conventional list.

Q34. Industrial standardisation

What helps manufacturers, customers and the public maintain competitiveness and quality simultaneously?

  • (A) Experimentation
  • (B) Balanced outlook on law
  • (C) Competition
  • (D) Industrial standardisation
View answer and explanation

Answer: (D) Industrial standardisation

Standards provide shared specifications, terminology, test methods and quality expectations. They can improve compatibility, reduce unnecessary variety and help buyers compare products. Manufacturers benefit from clearer production requirements, while users gain greater predictability and safety. Competition alone does not establish common technical requirements. Industrial standardisation is therefore the best match for the combined benefits described.

Q35. Law in engineering practice

Which concept stresses the necessity of rules and regulations in engineering practice?

  • (A) Standardisation
  • (B) Experimentation
  • (C) Balanced outlook on law
  • (D) Competition
View answer and explanation

Answer: (C) Balanced outlook on law

A balanced outlook recognises that law is necessary for safety, accountability and orderly professional practice, while also recognising the engineer’s responsibility to exercise ethical judgment. Compliance is a foundation, not a substitute for all professional reasoning. Standardisation concerns common technical requirements, whereas the question directly asks about the role of rules and regulations.

Q36. Testing to failure

Which testing approach continues until a component fails and may be expensive but realistic and useful?

  • (A) Prototype testing
  • (B) Destructive testing
  • (C) Simulation testing
  • (D) Safety-system component testing
View answer and explanation

Answer: (B) Destructive testing

Destructive testing deliberately loads, stresses or otherwise tests a specimen until damage or failure occurs. It can reveal actual failure loads, failure mechanisms and margins, but the tested specimen may be unusable afterwards. Prototype testing is a wider category and need not destroy the prototype. Simulation predicts behaviour through a model rather than necessarily producing a physical failure.

Q37. FMEA

Which analysis studies system components and their modes of failure?

  • (A) Failure Mode and Effects Analysis
  • (B) Scenario Analysis
  • (C) Fault-tree Analysis
  • (D) Event-tree Analysis
View answer and explanation

Answer: (A) Failure Mode and Effects Analysis

FMEA proceeds systematically through components or functions, identifies how each may fail and examines the effects of those failures. It is often described as a bottom-up approach. A fault tree starts from an undesirable top event and works backwards through combinations of causes; an event tree follows outcomes after an initiating event. The component-by-component emphasis identifies FMEA.

Q38. Hardware and human failures

Which analysis can combine hardware failures and human failures within one logical model?

  • (A) Failure Mode and Effects Analysis
  • (B) Scenario Analysis
  • (C) Fault-tree Analysis
  • (D) Event-tree Analysis
View answer and explanation

Answer: (C) Fault-tree Analysis

Fault-tree analysis represents an undesirable top event using logical combinations of contributing events, commonly with AND and OR gates. Basic events can include equipment malfunctions and human errors. This makes it useful for examining how different categories of failure can jointly produce an accident. FMEA is primarily organised around individual failure modes; the question’s focus is a combined causal logic.

Q39. Earth Day

Who among the listed people is associated with proposing the modern April Earth Day movement?

  • (A) John Muir
  • (B) Edward Abbey
  • (C) Aldo Leopold
  • (D) Gaylord Nelson
View answer and explanation

Answer: (D) Gaylord Nelson

US Senator Gaylord Nelson is associated with initiating the April 22 Earth Day environmental teach-in movement, first held in 1970. The other options are important environmental writers or conservation figures but are not the intended answer. Historically, an equinox Earth Day proposal is also associated with John McConnell; he is not among the choices. The standard April 22 context makes Gaylord Nelson the correct selection.

Q40. Brundtland and sustainability

Which is not an appropriate sustainable-development goal as phrased in the question?

  • (A) Fair distribution of resources to sustain development
  • (B) More democratic political systems
  • (C) Increased use of resources to supply increasing needs of underdeveloped countries
  • (D) Population levels compatible with ecological means
View answer and explanation

Answer: (C) Unqualified increased resource use

The intended distinction is between meeting essential needs sustainably and treating increasing resource consumption itself as the goal. The Brundtland framework stresses equity, participation, a sustainable population and conservation of the resource base. It does not forbid development or all increases in resource use in poorer countries. Read option C as an unqualified resource-consumption objective, which omits the ecological limits central to sustainable development.

Review note: Interpretation: option C is the best available answer; meeting essential needs in developing countries remains a central Brundtland objective.

Source: Brundtland Report, Chapter 2: needs, equity and ecological limits

Back to the answer key • Section navigation

Q41–Q60: Engineering mathematics and probability

For numerical questions, follow the setup before the arithmetic. C(n,r) denotes combinations, H denotes the unit-step function, and all infinite Fourier sums start at n = 1 unless another index is stated.

Q41. Inverse Laplace transform

Evaluate the inverse Laplace transform of 2s²/[(s² + 1)(s − 1)²].

  • (A) −cos t + e^(−t) − te^t
  • (B) −cos t − e^t + te^(−t)
  • (C) cos t + e^t + te^t
  • (D) −cos t + e^t + te^t
View answer and explanation

Answer: (D) −cos t + e^t + te^t

Resolve the rational function into partial fractions: 2s²/[(s² + 1)(s − 1)²] = −s/(s² + 1) + 1/(s − 1) + 1/(s − 1)². The standard inverse transforms are cos t, e^t and te^t respectively, with the first term carrying a minus sign. Adding them gives −cos t + e^t + te^t. The repeated factor (s − 1)² is what creates the te^t term.

Q42. Third-order differential equation

Solve y‴ + y″ = e^t + t + 1 with y(0) = y′(0) = y″(0) = 0.

  • (A) t³/6 + t + e^(2t)/2 − e^(−2t)/2
  • (B) t³/6 − t + e^t/2 − e^(−t)/2
  • (C) t³/6 − t − e^t/2 + e^(−2t)/2
  • (D) t^(−3)/6 − t + e^(2t)/2 − e^(−t)/2
View answer and explanation

Answer: (B) y = t³/6 − t + (e^t − e^(−t))/2

Set z = y″. Then z′ + z = e^t + t + 1. Multiplication by the integrating factor e^t and integration give z = e^t/2 + t + Ce^(−t). The condition z(0) = 0 gives C = −1/2. Integrating twice and applying the remaining zero initial conditions yields y = t³/6 − t + e^t/2 − e^(−t)/2. As a quick check, y″ = t + sinh t and y‴ = 1 + cosh t, whose sum is t + 1 + e^t.

Q43. Fourier series of |x|

Find the period-2 Fourier series of f(x) = x for 0 ≤ x ≤ 1 and f(x) = −x for −1 ≤ x < 0.

  • (A) ½ + Σ[2((−1)^n − 1)/(n²π²)]cos(nπx)
  • (B) ½ − Σ[2((−1)^n + 1)/(n²π²)]cos(nπx)
  • (C) ½ + Σ[((−1)^n + 1)/(n²π²)]cos(nπx)
  • (D) ½ − Σ[((−1)^n − 1)/(n²π²)]cos(nπx)
View answer and explanation

Answer: (A) ½ + Σ from n = 1 to ∞ of 2((−1)^n − 1)cos(nπx)/(n²π²)

Here f(x) = |x| is even, so all sine coefficients vanish. On −1 ≤ x ≤ 1, a₀ = ∫|x| dx = 1, giving constant term ½. For n ≥ 1, aₙ = 2∫₀¹ x cos(nπx) dx = 2[((−1)^n − 1)/(n²π²)]. Thus only odd harmonics remain, and the equivalent series is |x| = ½ − (4/π²)Σ cos((2k + 1)πx)/(2k + 1)², with k starting at zero. This matches option A.

Q44. Determinant row operations

For f(A) = det(A), which property is correct?

  • (A) f(I) ≠ 1
  • (B) Adding a multiple of one row to another leaves f unchanged
  • (C) The stated “interchanging some row by u” rule
  • (D) Subtracting two rows necessarily changes the determinant sign
View answer and explanation

Answer: (B) A row replacement Rᵢ → Rᵢ + kRⱼ leaves the determinant unchanged

Three rules should be kept distinct. Swapping two rows reverses the determinant’s sign. Multiplying one row by a scalar multiplies the determinant by that scalar. Adding a multiple of one row to a different row leaves the determinant unchanged. Also det(I) = 1. Only option B correctly states a standard determinant property; subtraction as a row replacement is not automatically a sign-changing operation.

Q45. Relative error

For u = 5xy²/z³, find the maximum first-order relative error at x = y = z = 1 when each input error has magnitude 0.001.

  • (A) 0.005
  • (B) 0.015
  • (C) 0.003
  • (D) 0.006
View answer and explanation

Answer: (D) 0.006, or 0.6%

Logarithmic differentiation gives du/u = dx/x + 2dy/y − 3dz/z. For a maximum-error estimate, add the absolute contributions: |Δu/u| ≈ |Δx/x| + 2|Δy/y| + 3|Δz/z|. At x = y = z = 1, this is (1 + 2 + 3) × 0.001 = 0.006. If all errors had specified positive signs, cancellation could occur; the printed options indicate the usual maximum-error interpretation.

Review note: Convention: maximum first-order relative error, not the signed change when all three errors are equal and positive.

Q46. Stopping distance with variable deceleration

A car has velocity 76 m/s at t = 2 s. Its acceleration is a(t) = −12t². How far does it travel before stopping?

  • (A) 81 m
  • (B) 57 m
  • (C) 32 m
  • (D) 43 m
View answer and explanation

Answer: (D) 43 m

Integrate acceleration: v(t) = C − 4t³. Since v(2) = 76, C = 108, so v(t) = 108 − 4t³. The car stops when 108 − 4t³ = 0, giving t = 3 s. Distance after braking is ∫₂³(108 − 4t³)dt = [108t − t⁴]₂³ = (324 − 81) − (216 − 16) = 43 m. Do not reset the given time variable to zero without also changing the acceleration expression.

Q47. Characteristic roots

For ay″ + by′ + cy = 0: statement 1 says complex roots occur when b² − 4ac < 0; statement 2 says a repeated real root occurs when b² − 4ac > 0. Which statement is incorrect?

  • (A) 1 only
  • (B) 2 only
  • (C) Both 1 and 2
  • (D) Neither 1 nor 2
View answer and explanation

Answer: (B) Statement 2 only

The characteristic equation is ar² + br + c = 0. Its discriminant Δ = b² − 4ac determines the roots: Δ < 0 gives a complex-conjugate pair; Δ = 0 gives a repeated real root; Δ > 0 gives two distinct real roots. Statement 1 is correct, but statement 2 uses the condition for distinct roots. The question asks for the incorrect statement, so select 2 only.

Q48. Damaged components: printed-option mismatch

A package contains 20 components, of which 5 are damaged. Four are drawn randomly without replacement. What is the probability that exactly one is damaged?

  • (A) 27/64
  • (B) 29/62
  • (C) 11/64
  • (D) 37/64
View answer and explanation

Calculated answer: 455/969 ≈ 0.46956; no printed option matches

This is a hypergeometric selection. Choose one damaged component in C(5,1) ways and three undamaged components in C(15,3) ways; choose the full sample in C(20,4) ways. Therefore P = C(5,1)C(15,3)/C(20,4) = (5 × 455)/4845 = 455/969. None of A–D equals this value. Even a with-replacement binomial approximation gives 4(¼)(¾)³ = 27/64, but that changes the sampling model. We do not replace the exact answer by that approximation merely to fit an option. Any official key or deletion decision should be checked separately.

Review note: Printed-option mismatch: exact answer is 455/969. A = 27/64 is the with-replacement/binomial result, not the exact answer for the stated finite sample.

Q49. Distance between two points

Find the magnitude of vector AB for A = (5,4) and B = (−3,2).

  • (A) √68
  • (B) √41
  • (C) √38
  • (D) √62
View answer and explanation

Answer: (A) √68 = 2√17

The displacement vector is B − A = (−3 − 5, 2 − 4) = (−8,−2). Its magnitude is √[(−8)² + (−2)²] = √(64 + 4) = √68. Squaring removes the signs of the coordinate differences. Do not add the absolute horizontal and vertical changes; that would measure a different, grid-based distance rather than straight-line Euclidean distance.

Q50. Laplace transform with a delayed term

For f(t) = sin t up to t = π/4 and f(t) = sin t + cos(t − π/4) afterwards, find L{f(t)}.

  • (A) (1 − se^(−πs/4))/(s + 1)
  • (B) (1 + se^(πs/4))/(s² − 1)
  • (C) (1 − se^(−πs/4))/(s² + 1)
  • (D) (1 + se^(−πs/4))/(s² + 1)
View answer and explanation

Answer: (D) (1 + se^(−πs/4))/(s² + 1)

Write f(t) = sin t + H(t − a)cos(t − a), where a = π/4 and H is the unit-step function. The second-shifting theorem gives L{H(t − a)g(t − a)} = e^(−as)G(s). Since L{sin t} = 1/(s² + 1) and L{cos t} = s/(s² + 1), the required transform is [1 + se^(−πs/4)]/(s² + 1). The added delayed term has a plus sign.

Q51. Mode-to-median ratio

A density is f(x) = 3x²/θ³ for 0 ≤ x ≤ θ, with θ > 0. Find mode divided by median.

  • (A) ∛2
  • (B) Fifth root of 2
  • (C) ∛5
  • (D) ∛7
View answer and explanation

Answer: (A) ∛2

The density increases throughout its support, so its mode is at x = θ. Integrating gives F(x) = x³/θ³. The median m satisfies F(m) = ½, so m = θ/∛2. Dividing mode by median gives θ/(θ/∛2) = ∛2. The parameter θ cancels, which is a useful check: changing the scale should not change this dimensionless ratio.

Q52. Binomial probability

Each baby independently has probability 0.1 of weighing below 2547 g. Among 20 babies, find P(X ≤ 1).

  • (A) 2.9(9/10)^19
  • (B) 2.9(1/10)^19
  • (C) 2.9(9/10)^20
  • (D) 2.9(1/10)^20
View answer and explanation

Answer: (A) 2.9(0.9)^19

Model X as Binomial(n = 20, p = 0.1). “At most one” includes zero and one: P(X ≤ 1) = (0.9)²⁰ + C(20,1)(0.1)(0.9)¹⁹. Factoring out (0.9)¹⁹ gives (0.9 + 2)(0.9)¹⁹ = 2.9(0.9)¹⁹. The expression is not P(X = 1) alone, so remember to include the zero-success term.

Q53. Conditional Poisson probability

If X is Poisson with λ = 1, find P(X ≥ 2 | X ≤ 4).

  • (A) 65/98
  • (B) 24/65
  • (C) 17/24
  • (D) 17/65
View answer and explanation

Answer: (D) 17/65

Conditional probability restricts the sample space to X = 0,1,2,3,4. Thus the numerator is P(2) + P(3) + P(4) and the denominator is P(0) + P(1) + P(2) + P(3) + P(4). Every Poisson term contains e^(−1), which cancels. The remaining numerator is 1/2! + 1/3! + 1/4! = 17/24; the denominator is 1 + 1 + 17/24 = 65/24. Their ratio is 17/65.

Q54. Machine breakdowns

There are 35 similar machines, each averaging 0.06 breakdowns per week. Under the intended Poisson model, find the probability of exactly three weekly breakdowns.

  • (A) 1.5435e^(−2.1)
  • (B) 2.1e^(−2.1)
  • (C) 2.205e^(−2.1)
  • (D) 4.305e^(−2.1)
View answer and explanation

Answer: (A) 1.5435e^(−2.1)

For independent Poisson breakdown processes, the total weekly count has mean λ = 35 × 0.06 = 2.1. Hence P(N = 3) = e^(−2.1)(2.1)³/3! = 1.5435e^(−2.1), approximately 0.189. The printed wording says “three machines,” while the offered expressions model three breakdown events. If distinct machines with at least one breakdown were counted exactly, a different model would be required. Option A follows the clearly intended aggregate Poisson calculation.

Review note: Modelling note: the options count breakdown events, not exactly three distinct machines experiencing at least one breakdown.

Q55. Balls distributed among boxes

Twelve balls are independently assigned with equal probability to three boxes. Find the probability that the first box receives exactly three balls.

  • (A) (220/27)(2/3)^9
  • (B) (22/270)(2/3)^9
  • (C) (27/20)(2/3)^9
  • (D) (190/27)(2/3)^8
View answer and explanation

Answer: (A) (220/27)(2/3)^9

For each ball, the probability of entering the first box is 1/3; the probability of entering either other box is 2/3. Therefore X is Binomial(12,1/3). P(X = 3) = C(12,3)(1/3)³(2/3)⁹ = (220/27)(2/3)⁹. This uses the standard interpretation that balls are assigned independently and boxes are equally likely; it does not assign equal probabilities to all possible occupancy triples.

Q56. Alternating dice game

A and B alternately roll two fair dice. A wins by obtaining a total of 6 before B obtains 7. If A starts, find A’s winning probability.

  • (A) 5/36
  • (B) 31/36
  • (C) 30/61
  • (D) 5/16
View answer and explanation

Answer: (C) 30/61

A obtains sum 6 with probability p = 5/36; B obtains sum 7 with probability q = 6/36. If both fail, the game returns to the same situation with A to play. Let W be A’s eventual winning probability. Then W = p + (1 − p)(1 − q)W. Thus W = (5/36)/[1 − (31/36)(30/36)] = 30/61. A’s first-roll success probability alone is not the probability of eventually winning.

Q57. Bayes and sign changes

Sanju initially writes plus with probability 1/3. Three subsequent people independently change the sign with probability 2/3 each. Given a final plus, find the probability that Sanju wrote plus.

  • (A) 13/27
  • (B) 8/27
  • (C) 13/41
  • (D) 18/41
View answer and explanation

Answer: (C) 13/41

An initial plus ends as plus after an even number of changes. That probability is (1/3)³ + C(3,2)(2/3)²(1/3) = 13/27. An initial minus becomes plus after an odd number of changes, with probability 14/27. Bayes’ theorem gives P(initial + | final +) = [(1/3)(13/27)]/[(1/3)(13/27) + (2/3)(14/27)] = 13/41. The prior probabilities 1/3 and 2/3 must be included.

Q58. A second white ball

B1 has 2 black and 1 white ball; B2 has 1 black and 2 white; B3 has 2 black and 2 white. A box is chosen uniformly. After drawing white, find the probability the next ball from that box is white without replacement.

  • (A) 1/3
  • (B) 1/2
  • (C) 2/3
  • (D) 3/5
View answer and explanation

Answer: (A) 1/3

The first-white probabilities for B1, B2 and B3 are 1/3, 2/3 and 1/2. After observing white, the posterior box probabilities are therefore 2/9, 4/9 and 1/3. The corresponding next-white probabilities are 0, 1/2 and 1/3. Multiply and add: (2/9)0 + (4/9)(1/2) + (1/3)(1/3) = 2/9 + 1/9 = 1/3. The observed first colour changes how likely each box is.

Q59. Triangular density

Daily bread sales X, in hundreds of pounds, have density Ax for 0 ≤ x ≤ 5 and A(10 − x) for 5 ≤ x ≤ 10. Find P(250 to 750 pounds).

  • (A) 1/2
  • (B) 3/8
  • (C) 3/4
  • (D) 3/5
View answer and explanation

Answer: (C) 3/4

The density is a triangle with base 10 and height 5A. Its area must equal one: ½ × 10 × 5A = 1, so A = 1/25. Convert the sales limits: 250 and 750 pounds correspond to X = 2.5 and 7.5. Each excluded tail is a small triangle with base 2.5 and height 0.1, hence area 0.125. The required central probability is 1 − 0.125 − 0.125 = 0.75 = 3/4.

Q60. Petrol-tank capacity

Daily sales X, in thousands of litres, have density 5(1 − x)^4 on 0 ≤ x ≤ 1. What capacity makes the probability of exhaustion 0.002?

  • (A) 601.9 litres
  • (B) 714.5 litres
  • (C) 709.1 litres
  • (D) 711.5 litres
View answer and explanation

Answer: (D) Approximately 711.5 litres

Let c be tank capacity measured in thousands of litres. Exhaustion occurs when X > c. The tail probability is ∫c¹ 5(1 − x)⁴ dx = (1 − c)⁵. Set (1 − c)⁵ = 0.002, giving c = 1 − (0.002)^(1/5) ≈ 0.711460. Convert back to litres by multiplying by 1000: approximately 711.46 litres, rounded to 711.5. The complement and the unit conversion are both essential.

Back to the answer key • Section navigation

Q61–Q80: Reasoning and quantitative aptitude

Q61. Increasing letter shifts

If KAVYA is coded as PGCGJ, how is ANITA coded?

  • (A) FTPBJ
  • (B) FTPJB
  • (C) GTBPJ
  • (D) ETPCJ
View answer and explanation

Answer: (A) FTPBJ

Compare successive letter positions: K→P is +5, A→G is +6, V→C is +7 with alphabet wraparound, Y→G is +8 and A→J is +9. Apply these position-specific shifts to ANITA: A+5 = F, N+6 = T, I+7 = P, T+8 = B and A+9 = J. This gives FTPBJ. The same original letter may receive different codes at different positions.

Q62. Directions and displacement

A man walks 4 km north, then 3 km left, 4 km right and finally 9 km right, turning relative to his current direction each time. Find his distance from home.

  • (A) 14 km
  • (B) 10 km
  • (C) 9 km
  • (D) 8 km
View answer and explanation

Answer: (B) 10 km

Track coordinates from (0,0). After 4 km north he is at (0,4). Turning left means west, so he reaches (−3,4). From west, a right turn points north, taking him to (−3,8). The final right turn points east; after 9 km he is at (6,8). Straight-line distance from home is √(6² + 8²) = 10 km. The 20 km total walked is not the displacement.

Q63. Combined work rate

Vishnu completes a job in 10 days and Ram in 15 days. How long do they take together?

  • (A) 9 days
  • (B) 12 days
  • (C) 6 days
  • (D) 8 days
View answer and explanation

Answer: (C) 6 days

Their daily work rates are 1/10 and 1/15 of the job. Together the rate is 1/10 + 1/15 = 3/30 + 2/30 = 1/6. Taking the reciprocal gives six days for the whole job. This assumes both work at their stated constant rates on a divisible task. Adding completion times would be incorrect because it is work rates, not durations, that combine.

Q64. Number-set analogy

Which set follows the same pattern as (3,16,25)?

  • (A) (6,36,64)
  • (B) (4,16,25)
  • (C) (1,14,16)
  • (D) (2,9,16)
View answer and explanation

Answer: (D) (2,9,16)

Read the given set as (n, (n + 1)², (n + 2)²). For n = 3 this produces (3,4²,5²) = (3,16,25). For n = 2 the corresponding set is (2,3²,4²) = (2,9,16). The first term is not itself squared. A useful analogy technique is to explain every term in the given set with one consistent rule before checking the alternatives.

Q65. Flats in a tower

A lives below B; C above D; D below A; B lives with E; F is on the top floor. Who is in the bottom flat?

  • (A) A
  • (B) C
  • (C) D
  • (D) E
View answer and explanation

Answer: (C) D

D is below A, and A is below B and therefore below E’s shared flat. C is explicitly above D, while F is on top. Thus every named person is either directly or indirectly placed above D. The precise position of C among the other middle floors is unnecessary: the available relations already identify D as the bottom occupant.

Q66. Family relationship

Avinash says of a woman’s photograph: “Her grandson Mohan is my brother’s nephew.” What is the intended relationship of the woman to Avinash?

  • (A) Mother
  • (B) Sister
  • (C) Grandmother
  • (D) Niece
View answer and explanation

Answer: (A) Mother, under the standard family-tree assumption

In the conventional exam interpretation, “my brother’s nephew” is taken to be Avinash’s son, Mohan. The woman is Mohan’s grandmother, so she is Avinash’s mother. The wording alone does not uniquely establish this: the grandmother could be on the child’s other parental side, or the nephew could be another sibling’s child. Mother is the intended listed choice, but it relies on the usual simplified family-tree assumption.

Review note: Family-tree ambiguity: Mother is the intended listed answer, not a uniquely forced relationship from the sentence alone.

Q67. Common walking days

Nilesh walks on Monday, Wednesday and Friday; Vicky on Monday, Thursday, Friday and Saturday. How often do their schedules coincide in a 31-day October beginning on Thursday?

  • (A) 8
  • (B) 9
  • (C) 7
  • (D) 10
View answer and explanation

Answer: (B) 9 times

The common days are Monday and Friday. With October 1 on Thursday, Fridays fall on 2,9,16,23 and 30: five Fridays. Mondays fall on 5,12,19 and 26: four Mondays. Therefore they meet on 5 + 4 = 9 scheduled walking days. First find the intersection of the weekly schedules, then count those weekdays in the month.

Q68. Word coding

“mod to bac” means “water and lemon”; “bac soc en” means “orange and tomato”; “en nad toz” means “buy fresh orange.” Which code means tomato?

  • (A) soc
  • (B) bac
  • (C) en
  • (D) nad
View answer and explanation

Answer: (A) soc

The first and second phrases share “and,” and their shared code is bac, so bac = and. The second and third phrases share “orange,” and their shared code is en, so en = orange. In the second phrase, bac and en are now identified, leaving soc for tomato. The order of words need not match the order of codes; shared occurrences provide the reliable deductions.

Q69. Alphabet values

Each letter is worth three times its alphabet position. Find the total for DHLNS.

  • (A) 183
  • (B) 176
  • (C) 171
  • (D) 161
View answer and explanation

Answer: (C) 171

The alphabet positions are D = 4, H = 8, L = 12, N = 14 and S = 19. Their sum is 4 + 8 + 12 + 14 + 19 = 57. Since every position is multiplied by three, the required total is 3 × 57 = 171. Add the positions first and multiply once to reduce arithmetic and avoid accidentally skipping a letter.

Q70. Calendar calculation

January 22, 2026 was Thursday. Which date in the second week of May 2026 was Monday?

  • (A) 14th
  • (B) 12th
  • (C) 10th
  • (D) 11th
View answer and explanation

Answer: (D) 11 May 2026

From January 22 to February 22 is 31 days; then to March 22 is 28 days, to April 22 is 31 days, and to May 11 is 19 days. The total is 109 days, with remainder 4 on division by 7. Four weekdays after Thursday is Monday. Therefore May 11 is the required date. February has 28 days because 2026 is not a leap year.

Q71. Ranks from the bottom

Ravi and Vishal are 8th and 14th from the top in a class of 33. Find their respective ranks from the bottom.

  • (A) 25th and 19th
  • (B) 26th and 19th
  • (C) 26th and 20th
  • (D) 25th and 20th
View answer and explanation

Answer: (C) 26th and 20th

For a class with N students and no ties, rank from bottom = N + 1 − rank from top. Ravi’s rank is 34 − 8 = 26; Vishal’s is 34 − 14 = 20. The extra one appears because the ranked student is included when counting from either end. A quick check is that top rank plus bottom rank must equal N + 1 = 34.

Q72. Round-robin matches

Ten teams each play every other team exactly once. How many matches take place?

  • (A) 90
  • (B) 60
  • (C) 35
  • (D) 45
View answer and explanation

Answer: (D) 45 matches

Each match corresponds to an unordered pair of teams. The count is C(10,2) = 10 × 9/2 = 45. Multiplying 10 by 9 alone counts every match twice, once from each team’s perspective. Dividing by two removes that duplication. For n teams in a single round-robin competition, the general formula is n(n − 1)/2.

Q73. Circular seating after swaps

Six people face the centre. F faces C; C is right of B and left of D; D is left of A; E is right of F. D swaps with E, and A swaps with B. Who is then left of C?

  • (A) E
  • (B) B
  • (C) D
  • (D) A
View answer and explanation

Answer: (D) A

One valid clockwise order before the swaps is C, B, E, F, A, D. For people facing the centre, a person’s immediate left is clockwise in this representation. Swapping D with E gives C, B, D, F, A, E. Swapping A with B gives C, A, D, F, B, E. A is now immediately to C’s left. Alternatively, C’s original left-hand neighbour B is replaced by A in the second swap.

Q74. Volumes of spheres

Two spheres have radii in the ratio 5:3. What is their volume ratio?

  • (A) 27:125
  • (B) 125:27
  • (C) 5:3
  • (D) 25:9
View answer and explanation

Answer: (B) 125:27

Sphere volume is V = (4/3)πr³. When taking the ratio, the common factor (4/3)π cancels, leaving the cube of the radius ratio: 5³:3³ = 125:27. Squaring would give the surface-area ratio, not volume. Remember the dimensional relationship: lengths scale as k, areas as k² and volumes as k³.

Q75. Contradictory reports

A speaks truth with probability 0.4 and B with probability 0.3. Under the standard independent binary-report model, how often do they contradict each other?

  • (A) 16%
  • (B) 36%
  • (C) 46%
  • (D) 26%
View answer and explanation

Answer: (C) 46%

Contradiction occurs when A tells the truth and B lies, or A lies and B tells the truth. Under independence these mutually exclusive cases have probabilities (0.4)(0.7) and (0.6)(0.3). Their sum is 0.28 + 0.18 = 0.46, or 46%. The calculation assumes the usual true/false reporting framework; unrestricted different false accounts of a complex incident would require more information.

Q76. Committee with at least two women

A 3-member committee is chosen uniformly from 5 men and 3 women. Find the probability it contains at least 2 women.

  • (A) 3/5
  • (B) 2/5
  • (C) 2/9
  • (D) 2/7
View answer and explanation

Answer: (D) 2/7

Total committees = C(8,3) = 56. The favourable cases are exactly two women and one man, or all three women. Their counts are C(3,2)C(5,1) = 15 and C(3,3) = 1. Therefore P = (15 + 1)/56 = 16/56 = 2/7. “At least two” includes three; overlooking that final committee changes the answer.

Q77. Sundays in a leap year

What is the probability that a leap year contains 53 Sundays?

  • (A) 2/7
  • (B) 5/7
  • (C) 3/7
  • (D) 2/9
View answer and explanation

Answer: (A) 2/7

A leap year has 366 days = 52 complete weeks + 2 extra days. Those extra days are consecutive weekdays. There will be 53 Sundays if the extra pair is Saturday–Sunday or Sunday–Monday. Two of the seven possible starting weekdays satisfy this condition. Assuming the seven starting weekdays are equally likely in the question’s standard model, the probability is 2/7.

Q78. Number series

Find the missing term in 1, 4, ?, 364.

  • (A) 9
  • (B) 19
  • (C) 12
  • (D) 17
View answer and explanation

Answer: (B) 19

A consistent rule is “square the previous term and add 3.” Starting with 1 gives 1² + 3 = 4. Next, 4² + 3 = 19. Finally, 19² + 3 = 361 + 3 = 364. The last step confirms the pattern and selects option B. Checking the rule against every transition is more reliable than choosing a number from only the first two terms.

Q79. Range of an integer expression

If n is an integer between 30 and 90, which value cannot be n + 7?

  • (A) 39
  • (B) 92
  • (C) 98
  • (D) 88
View answer and explanation

Answer: (C) 98

Subtract seven from each candidate. The implied n values are 32,85,91 and 81 respectively. Only 91 lies outside the stated interval, so 98 cannot be n + 7. This remains true whether “between” is interpreted strictly or with endpoints included. Directly recovering n from each option avoids unnecessary argument over endpoint conventions.

Q80. Maximum with positive natural numbers

If X + Y + Z = 13 and X,Y,Z are natural numbers, what is the maximum X under the positive-integer convention?

  • (A) 11
  • (B) 9
  • (C) 13
  • (D) 10
View answer and explanation

Answer: (A) 11

To maximise X, minimise the sum Y + Z. With natural numbers interpreted as 1,2,3,…, the smallest choices are Y = Z = 1. Then X = 13 − 1 − 1 = 11. Some mathematical conventions include zero among natural numbers, which would allow X = 13. The intended school-exam convention here is positive natural numbers; this assumption is stated so the reasoning remains explicit.

Review note: Convention: natural numbers are taken as positive integers. If zero were allowed, option C (13) would be possible.

Back to the answer key • Section navigation

Q81–Q100: Current affairs 2026 with primary sources

Each answer in this section is linked to a government or institutional primary source. Interpret the answers in the context of the dated event or announcement asked in the paper.

Q81. IREL rare-earth recycling plant

Where is the Rare Earth and Titanium Theme Park at which IREL established the recycling plant?

  • (A) Vijayapura
  • (B) Chamoli
  • (C) Bhopal
  • (D) Kottayam
View answer and explanation

Answer: (C) Bhopal

The Department of Atomic Energy’s parliamentary reply, published on 29 January 2026, identifies Bhopal as the location of the Rare Earth and Titanium Theme Park recycling plant. The plant recovers magnetic rare earths from end-of-life magnets. The same release distinguishes this facility from the samarium-cobalt permanent-magnet plant at Vizag. This distinction is the useful revision point: do not interchange the recycling-plant location and the magnet-manufacturing location.

Source: DAE/PIB, 29 January 2026: rare-earth minerals

Q82. AgriStack workshop venue

Where was the 29 January 2026 national workshop “AgriStack & AI in Agriculture: Now, Next & Beyond” held?

  • (A) New Delhi
  • (B) Mumbai
  • (C) Chennai
  • (D) Kolkata
View answer and explanation

Answer: (A) New Delhi

The Ministry of Agriculture and Farmers’ Welfare held the workshop at Sushma Swaraj Bhawan, New Delhi. AgriStack was discussed as digital public infrastructure for agriculture, connecting farmer identification, land information and service delivery. To retain this current-affairs fact, link the event to its organising ministry, date and exact venue. The question asks for the city, so New Delhi is the required level of detail.

Source: Agriculture Ministry/PIB, 29 January 2026: AgriStack workshop

Q83. GMPCS licence application

Which listed company’s application for a Unified Licence with GMPCS authorisation was rejected by DoT in the cited update?

  • (A) OneWeb India Communications Private Limited
  • (B) Jio Satellite Communications Limited
  • (C) Starlink Satellite Communications Private Limited
  • (D) Yotta Network Services Private Limited
View answer and explanation

Answer: (D) Yotta Network Services Private Limited

The 29 January 2026 parliamentary reply lists OneWeb, Jio Satellite Communications and Starlink among the companies issued the relevant authorisation. It lists Yotta and Nelco among rejected applications. Of the four choices, Yotta is therefore correct. GMPCS means Global Mobile Personal Communication by Satellite. This answer is tied to the dated government update; licensing positions should not be treated as permanently fixed.

Source: Communications Ministry/PIB, 29 January 2026: satellite services

Q84. First Training Squadron visit

Which port visit by the Indian Navy’s First Training Squadron concluded on 28 January 2026?

  • (A) Phuket Deep Sea Port, Thailand
  • (B) Port Klang, Malaysia
  • (C) Changi, Singapore
  • (D) Yangon, Myanmar
View answer and explanation

Answer: (A) Phuket Deep Sea Port, Thailand

The Defence Ministry’s release states that the squadron’s Phuket visit concluded with a passage exercise involving HTMS Huahin on 28 January 2026. The release itself was published the following day. This is a useful date-reading lesson: an event date and its publication date need not be identical. Associate Phuket with Thailand, which is the country specified in the correct option.

Source: Defence Ministry/PIB, 29 January 2026: Phuket visit

Q85. Leh civil aviation project

On which date was the cited civil aviation infrastructure project at Air Force Station Leh inaugurated?

  • (A) 28 January 2026
  • (B) 13 February 2026
  • (C) 21 March 2026
  • (D) 21 April 2026
View answer and explanation

Answer: (A) 28 January 2026

The government release dated 29 January 2026 records the inauguration as taking place on 28 January. The question asks when the project was inaugurated, so the event date, not the press-release date, must be selected. The project concerned civil aviation infrastructure at Air Force Station Leh. Keeping a separate “event date” column in a current-affairs notebook prevents this common one-day error.

Source: Defence Ministry/PIB, 29 January 2026: Leh infrastructure

Q86. Jal Jeevan Mission 2.0 extension

Up to when was the Jal Jeevan Mission period extended under JJM 2.0?

  • (A) December 2026
  • (B) December 2027
  • (C) December 2028
  • (D) December 2030
View answer and explanation

Answer: (C) December 2028

The Cabinet approved the restructured JJM framework on 10 March 2026, extending the mission to December 2028. The updated approach emphasises reliable water-service delivery and sustainability alongside infrastructure creation. The month matters because all four choices are expressed as December deadlines. The answer should be read in the context of this 2026 approval, rather than an earlier mission target.

Source: Cabinet/PIB, 10 March 2026: JJM extension

Q87. Budget cloud-services incentive

According to Budget 2026–27, until which year was the tax holiday announced for eligible foreign providers of global cloud services using Indian data centres?

  • (A) 2035
  • (B) 2040
  • (C) 2047
  • (D) 2050
View answer and explanation

Answer: (C) 2047

The Budget announcement identifies 2047 as the horizon for the specified foreign cloud-service providers using data-centre services from India. This is a targeted policy provision, not a blanket tax exemption for every technology company or every data-centre activity. For this MCQ, connect three elements: foreign provider, global cloud services and India-based data-centre services. The year completing that statement is 2047.

Source: Finance Ministry/PIB: Budget 2026–27 cloud-services provision

Q88. SOAR expansion

The President conferred SOAR certificates on 1 January 2026. What does SOAR stand for?

  • (A) Skill Optimization and AI Research
  • (B) Skilling for AI Readiness
  • (C) Smart Opportunities for AI Revolution
  • (D) Skill-Oriented Artificial Intelligence Reform
View answer and explanation

Answer: (B) Skilling for AI Readiness

The President of India’s official release expands SOAR as Skilling for AI Readiness. It records the launch of the #SkilltheNation challenge under this initiative on 1 January 2026. The initiative is associated with the Ministry of Skill Development and Entrepreneurship.

Source: President of India, 1 January 2026: SOAR and #SkilltheNation

Q89. Badalta Bharat campaign

The “Badalta Bharat Mera Anubhav” campaign is aligned with which vision?

  • (A) Digital India 2030
  • (B) Atmanirbhar Bharat 2035
  • (C) Viksit Bharat@2047
  • (D) Make in India 2040
View answer and explanation

Answer: (C) Viksit Bharat@2047

The Ministry of Information and Broadcasting describes the campaign as aligned with Viksit Bharat@2047. It invited citizens to express experiences of India’s transformation through creative formats, in collaboration with MyGov. The question tests the overarching vision rather than a specific technology or manufacturing scheme. Remember the campaign name together with its public-participation format and the 2047 development horizon.

Source: Information & Broadcasting Ministry/PIB, 3 January 2026: campaign winners

Q90. VYOMA Innovation Challenge

Which organisations collaborated with Digital India BHASHINI Division on the VYOMA Innovation Challenge?

  • (A) NITI Aayog and C-DAC
  • (B) Current AI and Kalpa Impact
  • (C) IndiaAI Mission and NIC
  • (D) ISRO and C-DOT
View answer and explanation

Answer: (B) Current AI and Kalpa Impact

The launch release of 2 June 2026 names Current AI and Kalpa Impact as BHASHINI’s partners. The challenge promotes multilingual, voice-first AI that can work in offline or low-connectivity environments. The context is edge AI and linguistic access, which helps distinguish it from unrelated space, telecom or general digital-governance partnerships appearing in the distractors.

Source: MeitY/PIB, 2 June 2026: VYOMA launch

Q91. Breast-cancer nanocarrier research

Which institute developed the reported biodegradable nanocarrier platform for targeted gene therapy in breast cancer?

  • (A) Indian Institute of Science, Bengaluru
  • (B) Agharkar Research Institute, Pune
  • (C) National Centre for Cell Science, Pune
  • (D) Tata Memorial Centre, Mumbai
View answer and explanation

Answer: (B) Agharkar Research Institute (ARI), Pune

The Department of Science and Technology’s release attributes the reported work to the Nanobioscience Group at Agharkar Research Institute, Pune. The platform is designed to deliver a targeted gene-silencing approach using biodegradable nanocarriers. This is a research-development report; it should not be read as an announcement of a routinely available or clinically proven treatment. The exam’s factual target is the institute and city.

Source: DST/PIB, 3 June 2026: nanocarrier research

Q92. India–South Africa technology priorities

Which trio was highlighted as the key priority for the next phase of India–South Africa cooperation in the cited announcement?

  • (A) Nuclear energy and defence manufacturing
  • (B) Artificial Intelligence, Digital Infrastructure and Advanced Manufacturing
  • (C) Agriculture and food processing
  • (D) Space exploration and fisheries
View answer and explanation

Answer: (B) AI, Digital Infrastructure and Advanced Manufacturing

The 3 June 2026 government announcement explicitly foregrounds these three fields as key priorities. It also describes a wider science-and-technology relationship. The question’s wording asks for the highlighted trio, not every field in which the countries cooperate. Revise the announcement as a linked set: partner country South Africa; future-technology focus; AI, digital infrastructure and advanced manufacturing.

Source: DST/PIB, 3 June 2026: bilateral technology priorities

Q93. Reading the priority list precisely

Which option was not one of the three headline priorities identified in the preceding India–South Africa announcement?

  • (A) Artificial Intelligence
  • (B) Digital Infrastructure
  • (C) Advanced Manufacturing
  • (D) Quantum Computing
View answer and explanation

Answer: (D) Quantum Computing

AI, digital infrastructure and advanced manufacturing are the three headline priorities. Quantum computing is therefore the intended exclusion from that particular list. However, the same release also discusses quantum technologies in the wider partnership context. The correct inference is “not one of the named headline trio,” not “the countries never discussed quantum cooperation.” This wording distinction prevents an overbroad conclusion.

Review note: Wording note: quantum technologies are discussed in the wider release, although not in its three-item headline priority list.

Source: DST/PIB, 3 June 2026: full announcement and wider context

Q94. BHASHINI’s Nepal MoU

With which Nepal institution did Digital India BHASHINI Division sign the cited MoU?

  • (A) Tribhuvan University
  • (B) Nepal Academy of Science and Technology
  • (C) Kathmandu University’s Centre for Digital Public Infrastructure and Artificial Intelligence
  • (D) Pokhara University
View answer and explanation

Answer: (C) Kathmandu University’s DPI-AI Centre

The 6 June 2026 release identifies Kathmandu University’s Centre for Digital Public Infrastructure and Artificial Intelligence as the partner. The collaboration concerns language AI, multilingual public infrastructure and digital inclusion across India and Nepal. The institutional sub-unit matters: the option names the centre within Kathmandu University, rather than merely a broad bilateral government arrangement.

Source: MeitY/PIB, 6 June 2026: BHASHINI–Kathmandu University MoU

Q95. BRICS Science Academies Forum

Who convened the first meeting of the BRICS Science Academies Forum 2026?

  • (A) NITI Aayog
  • (B) Department of Science and Technology
  • (C) Indian National Science Academy
  • (D) Council of Scientific and Industrial Research
View answer and explanation

Answer: (C) Indian National Science Academy (INSA)

The official 9 June 2026 release states that INSA convened the first meeting as part of India’s BRICS Presidency. The meeting addressed responsible AI, sustainable development and Global South cooperation. Distinguish the convening academy from the government department that published or supported the announcement. The presence of the Science and Technology Ministry’s name on a release does not make DST the convenor.

Source: DST/PIB, 9 June 2026: INSA convenes BRICS academies

Q96. Distance of NGC 2139

Approximately how far from Earth is spiral galaxy NGC 2139 in the cited report?

  • (A) 45.3 million light-years
  • (B) 60.2 million light-years
  • (C) 90.7 million light-years
  • (D) 120.5 million light-years
View answer and explanation

Answer: (C) 90.7 million light-years

The DST report on supernova SN 2023zcu gives the host galaxy’s approximate distance as 90.7 million light-years. A light-year is a distance: the distance light travels in one year. Astronomical distance estimates can vary with measurement methods; the question refers to the rounded figure in this report. Associate NGC 2139 with SN 2023zcu and the reported 90.7-million-light-year scale.

Source: DST/PIB, 12 June 2026: NGC 2139 and SN 2023zcu

Q97. Type IIP supernova progenitor

Which type of star typically produces a Type IIP supernova?

  • (A) White dwarf
  • (B) Blue giant
  • (C) Brown dwarf
  • (D) Red supergiant
View answer and explanation

Answer: (D) Red supergiant

Type IIP supernovae are typically core-collapse explosions of massive red supergiants that retain a substantial hydrogen envelope. The P refers to a plateau in the light curve, linked to the evolving hydrogen-rich envelope after the explosion. A white dwarf is the standard association for Type Ia supernovae, not Type IIP. The source report explains this red-supergiant origin in connection with the study of SN 2023zcu.

Source: DST/PIB, 12 June 2026: Type IIP supernova explanation

Q98. Varya video AI model

Which company launched the distilled video AI model Varya with IndiaAI Mission support?

  • (A) Sarvam AI
  • (B) Krutrim AI
  • (C) Avataar AI
  • (D) Hanooman AI
View answer and explanation

Answer: (C) Avataar AI

The 12 June 2026 MeitY release identifies Avataar as Varya’s developer. It describes support through the IndiaAI Mission and a distillation approach intended to make video generation more efficient and relevant to Indian contexts. In machine learning, distillation transfers capabilities from a larger teacher model to a more compact student model. For this MCQ, retain the direct association Varya → Avataar → IndiaAI Mission support.

Source: MeitY/PIB, 12 June 2026: Varya launch

Q99. SME-led semiconductor facility

Which state inaugurated its first semiconductor plant, described as India’s first SME-led semiconductor facility?

  • (A) Gujarat
  • (B) Karnataka
  • (C) Rajasthan
  • (D) Tamil Nadu
View answer and explanation

Answer: (C) Rajasthan

The 15 May 2026 MeitY release identifies Sahasra Semiconductors’ facility at Bhiwadi, Rajasthan. The question’s distinguishing phrase is “SME-led,” so it should not be confused with separate large semiconductor investments in other states. In revision, connect the state Rajasthan, the location Bhiwadi and the company Sahasra. Avoid enlarging the claim into a statement that this was India’s first semiconductor activity of any kind.

Source: MeitY/PIB, 15 May 2026: Rajasthan semiconductor plant

Q100. Great Indian Bustard breeding

Where were the two new chicks in the cited Great Indian Bustard captive-breeding update hatched?

  • (A) Desert National Park, Jaisalmer
  • (B) Conservation Breeding Centre, Jaisalmer
  • (C) National Zoological Park, New Delhi
  • (D) Keoladeo National Park, Bharatpur
View answer and explanation

Answer: (B) Conservation Breeding Centre, Jaisalmer

The 13 March 2026 environment-ministry update reports two new chicks at Rajasthan’s Conservation Breeding Centre, corresponding to option B. It distinguishes one chick from natural mating and one from artificial insemination. The key distinction is a managed conservation-breeding facility rather than simply a national park or a zoo. Read the question as referring to that dated two-chick update; later programme totals do not change the event being asked about.

Source: Environment Ministry/PIB, 13 March 2026: two GIB chicks

Back to the answer key • Section navigation

Review notes: printed options, wording and assumptions

QuestionHow to interpret the solution
Q40Interpretation: option C is the best available answer; meeting essential needs in developing countries remains a central Brundtland objective.
Q45Convention: maximum first-order relative error, not the signed change when all three errors are equal and positive.
Q48Printed-option mismatch: exact answer is 455/969. A = 27/64 is the with-replacement/binomial result, not the exact answer for the stated finite sample.
Q54Modelling note: the options count breakdown events, not exactly three distinct machines experiencing at least one breakdown.
Q66Family-tree ambiguity: Mother is the intended listed answer, not a uniquely forced relationship from the sentence alone.
Q80Convention: natural numbers are taken as positive integers. If zero were allowed, option C (13) would be possible.
Q93Wording note: quantum technologies are discussed in the wider release, although not in its three-item headline priority list.

These notes are part of the explanation, so learners can distinguish an exact mathematical result from an intended approximation or a conventional exam assumption. They should not be represented as UPSC-confirmed errors or accepted objections.

What this paper teaches about preparation

The uploaded GAT paper is broad. Its first 40 questions move across environment and ecology, mechanics, production management, materials, computing, communication, safety and ethics. Questions 41–60 require engineering mathematics and probability; Questions 61–80 emphasise reasoning and quantitative aptitude; Questions 81–100 test dated current affairs. These are editorial topic groupings of this paper, not an official syllabus or a prediction of future weightage.

  • Numerical foundations: revise partial fractions, Laplace transforms, differential equations, Fourier series and error propagation. The working in Q41–46 shows why formula recall must be paired with correct initial conditions and limits.
  • Probability model selection: distinguish binomial, hypergeometric and Poisson models before calculating. Q48 is particularly useful for understanding why finite sampling without replacement differs from independent trials.
  • Reasoning accuracy: draw coordinates for direction questions, track actual seats after swaps and state the convention used for family relations or natural numbers.
  • Current-affairs source reading: record the event date, announcement date, institution and location separately. Several questions can be answered accurately by reading the exact scope of the official release.

A practical revision plan using these 100 solutions

  • Attempt: take the original paper in one 120-minute sitting and record both your response and confidence level.
  • Diagnose: classify every error as a concept gap, a calculation mistake, a misread condition or a factual recall gap. Avoid treating all wrong answers alike.
  • Rebuild: use the worked explanation to write the governing rule in one sentence, then solve a changed-number version of the question.
  • Retest: revisit incorrect and low-confidence items after a short gap, without looking at the key first. Keep Q48 and the other review-note questions separate from routine score comparisons.

For deeper practice on CrackTarget, use the PYQ study method, the time, work and speed practice set and the mock-test analysis guide. The Science archive and Quantitative Aptitude archive provide related revision material.

Frequently asked questions

Which recruitment does this question paper cover?

This post focuses on Scientist-B (Atmospheric Sciences), India Meteorological Department, Ministry of Earth Sciences: Advertisement 05/2026, Vacancy No. 26050512623, seven posts. The booklet is the shared GAT combined recruitment paper for Assistant Director Grade I/II and Scientist-B.

How many questions and marks are in the uploaded paper?

The Series A booklet has 100 questions, a maximum of 300 marks and a two-hour time limit. Its one-third negative marking means +3 for a correct response and −1 for a wrong response, with no penalty for an unattempted question.

Does CrackTarget provide explanations for all 100 questions?

Yes. Every numbered question from 1 to 100 has a question-wise solution. Numerical questions include the setup and calculation. Current-affairs answers include primary-source links. Q48 is solved explicitly even though none of its printed choices matches the exact result.

Is this the official UPSC answer key?

No. The downloadable file is the original uploaded question-paper scan; the explanations and key are independently prepared by CrackTarget. Check UPSC separately for its official answer key and any final decisions.

Can I use these answer letters for another booklet series?

Only after matching the question and its option order. The numbering and answer letters on this page apply to Series A, T.B.C. HCLM-B-NPT.

Is this a specialised Atmospheric Sciences subject paper?

The cover is labelled GAT and the questions span general engineering, mathematics, aptitude and current affairs. Do not treat this upload as a separate specialist atmospheric-science theory paper.

Found a point to discuss? Comment with the Series A question number, your calculation or primary source, and the proposed correction. A reasoned explanation helps other learners understand the issue.


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