UPSC Geo-Scientist Prelims 2020 General Studies (Paper I): answer key and solutions

Answer: (b) cannot coexist if they occupy the same niche.

Gause's principle (competitive exclusion): two species competing for the same limiting resources (same niche) cannot coexist indefinitely; one excludes the other. Coexistence needs niche differentiation (resource partitioning). Gause showed it with Paramecium aurelia and P. caudatum in culture.

Answer: (a) Hydrogen sulphide (H₂S).

Vent bacteria are chemosynthetic: they oxidise H₂S to get energy and use it to fix CO₂. H₂S is the energy source they 'feed' on. Tube worms (Riftia) host these bacteria; they are not their food. Remember: chemosynthesis = energy from inorganic oxidation, not light.

Answer: (d) solely from the oxidation of inorganic electron donors in the absence of light.

Chemo = energy from chemical oxidation, not light. Auto = carbon from CO₂, so the electron donors are inorganic (H₂S, NH₃, Fe²⁺, H₂). They work in the absence of light. Options with 'light' are photo-trophs; 'organic donors' are chemo-organotrophs.

Answer: (a) 1 % - 3 %

Plants fix only about 1–3% of incident sunlight (often quoted as ~1–2% of PAR) as gross primary production. The rest is reflected, transmitted or lost as heat and in transpiration. Remember: 10% law applies to transfer between trophic levels, not to light capture.

Answer: (c) water logged wet ground.

A wetland is land that is waterlogged or shallow-flooded long enough for hydric soils and water-tolerant plants (marshes, swamps, bogs, mangroves). The defining feature is saturation of the ground, not the source or speed of the water.

Answer: (d) flocculation of clays resulting in formation of mud deposits.

At the river-sea contact (estuary), dissolved salts neutralise the charge on suspended clay particles. The clays flocculate, settle and build mud flats. Remember: salinity, not just loss of velocity, drives estuarine mud deposition.

Answer: (b) 20,000 lux.

Heliophytes (sun-loving plants) need high light; the mean maximum illumination quoted for them in ecology texts is about 20,000 lux, while sciophytes (shade plants) need far less. Answer as per the official key.

Answer: (c) No nectar

Anemophily = wind pollination. Flowers are small, dull, no nectar, no scent; pollen is light and abundant; stigmas are large and feathery to catch pollen. So bright colour, scent and dwarf stigma are features of insect flowers or wrong.

Answer: (b) chemical exchange between sea water and its substratum as well as hydrothermal emissions.

Sea salt comes from rock weathering brought by rivers, exchange with the sea floor and hydrothermal emissions (Cl⁻ and other volatiles from vents and volcanoes). Evaporation only concentrates salt; it does not supply it. Rain is nearly salt-free.

Answer: (a) natural grasslands.

Natural grasslands carry the highest species richness because they are old, undisturbed and have many niches. Semi-natural, artificial and managed (watered, fertilised) grasslands are dominated by a few species. Remember: management for yield lowers richness.

Answer: (d) Carbon dioxide

CO₂ gives the largest share of anthropogenic radiative forcing (about two-thirds of the forcing from long-lived greenhouse gases), from fossil fuel burning and land-use change. CH₄ is stronger per molecule but far less abundant.

Answer: (a) Wetlands

Wetlands are the largest natural source of methane (anaerobic decay by methanogens). Cattle belching and pipeline leaks are anthropogenic sources; burning wood mainly gives CO₂.

Answer: (b) high latitude regions.

Ozone depletion is greatest at high latitudes, especially the Antarctic ozone hole in spring. Polar stratospheric clouds form in the cold polar vortex and convert stable chlorine into active Cl that destroys O₃ when sunlight returns.

Answer: (c) PM 10 and PM 2.5

NAAQS (2009) notify PM₁₀ (particles ≤ 10 µm) and PM₂.₅ (≤ 2.5 µm) along with SO₂, NO₂, O₃, CO, NH₃, Pb, benzene, benzo(a)pyrene, As and Ni — 12 pollutants in all.

Answer: (d) 40 cm

IPCC projections put global mean sea level rise by 2100 at roughly 0.3–1 m depending on emissions; the broad mid estimate used in texts of that time is about 40 cm (IPCC AR5: 26–82 cm). Main causes: thermal expansion and melting ice.

Answer: (b) causes oxygen starvation.

Solubility of O₂ falls as water temperature rises, while metabolic rate of aquatic animals rises. Result: oxygen starvation (low DO), fish kills. Heat may harm plants and microbes too, but the basic harm is loss of dissolved oxygen.

Answer: (c) less than 5 mg O₂/dm³/5 day.

BOD = O₂ used by microbes to oxidise organic matter in 5 days at 20 °C. Clean, unpolluted river water has BOD < 5 mg/L (often 1–2). Untreated sewage: 100–400 mg/L. Remember: higher BOD = more pollution.

Answer: (c) oxygen inhalation by plants.

Pneumatophores are negatively geotropic breathing roots of mangroves (Avicennia, Rhizophora). Waterlogged mud lacks oxygen, so these roots rise above the surface and take in air through lenticels. Prop/stilt roots give support, not pneumatophores.

Answer: (a) Rain

A bog is ombrotrophic: it gets water only from precipitation (rain, snow). So it is acidic, nutrient-poor and dominated by Sphagnum moss and peat. A fen gets ground or surface water and is less acidic.

Answer: (a) prevent the reduction in photosynthetic activity.

Hedgerows act as windbreaks and give partial shade. In high insolation, excess light and heat cause stomatal closure and photo-inhibition; hedgerows prevent the fall in photosynthetic activity and also cut moisture loss. Key holds (a).

Answer: (b) they act like a greenhouse on the surface of the planet.

The name comes from the greenhouse analogy: like glass, these gases let short-wave sunlight in but trap outgoing long-wave (infrared) radiation, warming the surface and lower atmosphere. Colour has nothing to do with it.

Answer: (c) 2002

India signed the CBD in 1992 (ratified 1994) and enacted the Biological Diversity Act in 2002; Biological Diversity Rules 2004. It set up the National Biodiversity Authority (Chennai), State Biodiversity Boards and BMCs.

Answer: (b) 2030

India's INDC/NDC under the Paris Agreement (2015): cut emission intensity of GDP by 33–35% below 2005 levels by 2030, 40% non-fossil power capacity and a 2.5–3 billion t CO₂ carbon sink. (2022 update raised it to 45%.)

Answer: (c) Fisheries

The 40th Amendment (1976) rewrote Article 297: vests in the Union all lands, minerals and things of value under the ocean within territorial waters and continental shelf, and all other resources of the EEZ. 'Fisheries' as such is not named.

Answer: (c) Nuclear minerals

Nuclear minerals (uranium, thorium) are finite, mined resources → non-renewable. Wind, sunlight and biofuels are replenished naturally. Remember: nuclear power is low-carbon but not renewable.

Answer: (a) North-East monsoon and South-West monsoon

India's climate is controlled by the South-West monsoon (June–Sept, ~75% of rain) and the North-East monsoon (retreating/winter, rain on Tamil Nadu coast). This seasonal reversal of winds defines the 'monsoon type' climate.

Answer: (d) poor and vulnerable.

Ayushman Bharat–PMJAY (2018) gives ₹5 lakh per family per year cover for secondary and tertiary care to poor and vulnerable families identified by SECC 2011 (about 10.74 crore families then). It is not universal.

Answer: (c) It is wage employment scheme for the landless agricultural labour

DAY–NRLM is a self-employment and livelihood mission: mobilise poor households into SHGs, give skills and access to credit. It is not a wage employment scheme; wage employment for unskilled labour is MGNREGA.

Answer: (d) Wool

The Company exported Indian cotton textiles (muslin, calico), silk, indigo, saltpetre, spices. Wool was not an Indian export to Europe; Britain itself was a wool producer.

Answer: (c) Blue water

Blue water = fresh surface and groundwater (rivers, lakes, aquifers) — the source of human withdrawals for irrigation, industry and homes. Green water = soil moisture used by plants; grey water = used/polluted water.

Answer: (a) It is a constitutional position under Article 76 of the Constitution of India

The Attorney General is constitutional (Art. 76). The Solicitor General is a statutory post (Law Officers (Conditions of Service) Rules, 1987), appointed by the ACC, and assists the AG. So statement (a) is wrong.

Answer: (c) Committee on Members of Parliament Local Area Development Schemes

The three financial committees are Estimates, Public Accounts and Public Undertakings. The MPLADS Committee (Lok Sabha) is not one of them.

Answer: (a) Cabinet Secretary

The Civil Services Board (for transfers and postings of senior officers) at the Centre is headed by the Cabinet Secretary; in states, the Chief Secretary heads the state CSB (as directed in T.S.R. Subramanian v. UoI, 2013).

Answer: (a) Rangarajan Commission

The NSC (2006) was set up on the recommendation of the Rangarajan Commission (National Statistical Commission report, 2001) to reform official statistics. First chairman: Suresh Tendulkar.

Answer: (b) India

India set up Asia's first EPZ at Kandla (Gujarat) in 1965. EPZs were later converted into SEZs (SEZ Act, 2005). China's SEZs came only in 1980.

Answer: (c) 5th

Germanwatch's Global Climate Risk Index 2020 (data for 2018) ranked India 5th most affected, after Japan, Philippines, Germany and Madagascar — due to the Kerala floods and cyclones Titli and Gaja.

Answer: (a) immunization of children.

Mission Indradhanush (2014) aims at full immunisation of children (< 2 years) and pregnant women against vaccine-preventable diseases. Intensified Mission Indradhanush followed later.

Answer: (d) It recommends measures regarding the salary of government employees

Under Art. 280, the FC recommends sharing of taxes (vertical and horizontal), principles of grants-in-aid (Art. 275), and measures to augment state consolidated funds for local bodies. Salaries of government employees are fixed by Pay Commissions, not the FC.

Answer: (b) Union, State and Concurrent Lists.

Seventh Schedule (Art. 246) has the Union List, State List and Concurrent List. Languages = 8th Schedule; land reforms = 9th; anti-defection = 10th.

Answer: (b) unorganized workers.

Swavalamban (2010) gave a co-contribution of ₹1,000 a year to unorganised sector workers joining the NPS-Lite pension. It was later replaced by Atal Pension Yojana (2015).

Answer: (b) Assam Rifles

Assam Rifles, raised in 1835 as the Cachar Levy, is the oldest paramilitary force in India. CRPF dates from 1939, BSF 1965, ITBP 1962.

Answer: (b) Women

After the Delhi gang rape (Dec 2012), the Justice J.S. Verma Committee proposed reforms of criminal law on crimes against women. It led to the Criminal Law (Amendment) Act, 2013.

Answer: (c) Supreme Court

Residuary powers lie with Parliament (Art. 248, entry 97 of the Union List). Whether a matter falls under it is a question of interpretation of the Constitution, decided finally by the courts, i.e. the Supreme Court.

Answer: (c) First woman pilot of Indian Navy

Sub-Lt Shivangi (Dec 2019) became the first woman pilot of the Indian Navy, flying the Dornier aircraft at Kochi.

Answer: (a) 2nd Five Year Plan

The 2nd Five Year Plan (1956–61, Mahalanobis model) stressed heavy industry and adopted the goal of a 'socialistic pattern of society' set by the Avadi session of Congress (1955) and Parliament (1954).

Answer: (a) Article 44

Article 44 (DPSP): the State shall endeavour to secure a Uniform Civil Code for citizens throughout India. Art. 40 = village panchayats; 39A = free legal aid; 41 = right to work, education, public assistance.

Answer: (b) A.P.J. Abdul Kalam

PURA (Providing Urban Amenities in Rural Areas) was proposed by Dr. A.P.J. Abdul Kalam: physical, electronic and knowledge connectivity to make villages economically viable.

Answer: (d) Industrialization and participation of private players

Gandhian development: limited wants, self-sufficient villages, cottage industries, decentralisation, harmony with nature. Gandhi opposed large-scale industrialisation and profit-driven private capital. So (d) is not Gandhian.

Answer: (a) The poverty line

Head count ratio = share of population below the poverty line. It counts how many are poor, but not how poor (poverty gap index does that).

Answer: (a) Department of Rural Development and Department of Land Resources

The Ministry of Rural Development has two departments: Department of Rural Development and Department of Land Resources. Drinking Water and Sanitation became a separate ministry (2011; now Jal Shakti).

Answer: (b) Himachal Pradesh

Himachal Pradesh is called the 'Fruit Bowl of India' for apples, plums, peaches, apricots and other temperate fruits grown in its hill districts.

Answer: (c) Godavari and Krishna

Telangana is drained mainly by the Godavari (north) and the Krishna (south), with tributaries such as Manjira, Pranhita and Musi.

Answer: (d) Punjab

Punjab produces far more wheat than it consumes, so it gives the largest marketable surplus and the largest share of central pool procurement. UP produces the most wheat but consumes much of it.

Answer: (a) Bihar

Chhattisgarh borders UP, Jharkhand, Odisha, Andhra Pradesh, Telangana, Maharashtra and Madhya Pradesh (7 states). It does not touch Bihar; Jharkhand lies between them.

Answer: (c) Goa and Haryana

Among the options, Goa has the highest per capita NSDP, and Haryana is among the top major states (ahead of Kerala and Punjab in that period). Sikkim and Delhi are also high but are not offered.

Answer: (a) 42 percent.

Insolation falls with latitude because the sun's rays are more oblique and pass through more air. Annual insolation at the poles is roughly 40% of the equator's (texts quote ~42%). Remember: equator gets the maximum annual total.

Answer: (c) 183 days in a year.

Census of India: Main worker = worked for 6 months or more (≥ 183 days) in the reference year. Marginal worker = worked for less than 183 days.

Answer: (d) Meghalaya

In most of India, women migrate on marriage to the husband's home (patrilocal). In Meghalaya (Khasi and Garo, matrilineal), the husband often moves to the wife's home, so female marriage migration is different.

Answer: (d) China

China is the world's largest producer of cereals (rice, wheat, maize together), followed by the USA and India.

Answer: (a) Three

The National Commission on Agriculture (1976) classified social forestry into three categories: urban forestry, rural forestry and farm forestry.

Answer: (d) Puducherry

Areas (2019, before J&K reorganisation): Puducherry ~490 km², Chandigarh ~114 km², Daman and Diu ~112 km², Lakshadweep ~32 km². So Puducherry is largest among the options.

Answer: (d) annual averages and seasonal variations in temperature and precipitation.

Climate classifications (e.g. Köppen) use annual averages and seasonal patterns of both temperature and precipitation, linked to vegetation. Neither alone is enough.

Answer: (a) USA

FAO data show the USA among the highest per capita food supply, about 3,600–3,700 kcal per person per day, above Australia, the Netherlands and Saudi Arabia.

Answer: (a) Rainforest

Tropical rainforests have the highest NPP per unit area among the options (~2,000 g/m²/yr). Extreme deserts are lowest. (Swamps, estuaries and reefs also rank high, but are not offered.)

Answer: (b) Telangana

Telangana is landlocked, so it has no mangroves. Odisha (Bhitarkanika), AP (Godavari-Krishna delta) and West Bengal (Sundarbans) all have mangrove forests.

Answer: (a) Bande Mataram – Bankim Chandra

Bankim Chandra wrote the song 'Bande Mataram' (Anandamath), but the newspaper Bande Mataram (1905) was started by Bipin Chandra Pal and edited by Aurobindo Ghosh. Others are correct: Kesari–Tilak, Bombay Samachar–Fardunjee Marzban, Al-Hilal–Azad.

Answer: (b) The tribes were declared criminal on the basis of their profession

The Criminal Tribes Act, 1871 labelled whole communities as 'criminal by birth' (hereditary criminality), not by profession. Notified groups had to live in notified settlements and needed a pass to move. So (b) is not a feature.

Answer: (c) Permanent

Under the Permanent Settlement (1793, Bengal), the sunset law let the Company auction estates of zamindars who failed to pay revenue on time. The Raja of Burdwan's lands were auctioned in 1797.

Answer: (b) Kol rebellion, Santhal uprising, Deccan riots

Kol rebellion (1831–32) → Santhal uprising (1855–56) → Deccan riots (1875). Tebhaga is 1946–47, Kuka revolt 1871–72, so other options break the order.

Answer: (d) The Congress did not support the movement

Khilafat movement (1919–24), led by the Ali brothers, demanded the Sultan keep control of holy places and enough territory. Gandhi and the Congress supported it, merging it with Non-Cooperation. So (d) is wrong.

Answer: (a) Sardar Vallabhbhai Patel, Dr. Rajendra Prasad and Dr. M.A. Ansari

After Non-Cooperation ended (1922), no-changers — Vallabhbhai Patel, Rajendra Prasad, M.A. Ansari, C. Rajagopalachari — opposed council entry. Pro-changers (C.R. Das, Motilal Nehru) formed the Swaraj Party.

Answer: (c) 1938

At the Haripura session (1938), Congress declared that purna swaraj included the princely states, and backed people's movements there.

Answer: (a) Ahichchhatra, Uttar Pradesh

Life-size terracotta Ganga and Yamuna figures (Gupta period, ~5th century) come from Ahichchhatra (Bareilly, UP); now in the National Museum, Delhi.

Answer: (d) Anglo-Mohammedan Defence Association – Nawab Muhsin-ul-Mulk

Anglo-Muhammadan Defence Association (1893) was founded by Sayyid Ahmad Khan with Theodore Beck, not Muhsin-ul-Mulk. Others correct: Mohammedan Literary Society–Abdul Latif (1863), CNMA–Ameer Ali, Educational Conference–Sayyid Ahmad Khan.

Answer: (c) Poona pact

The Poona Pact (1932) replaced separate electorates (Communal Award) with reserved seats for Depressed Classes in a joint (general) electorate — 148 seats in provincial legislatures and 18% in the central legislature.

Answer: (a) William Hawkins

William Hawkins reached Jahangir's court (1609) for the English Company. Jahangir liked his Turkish, made him a mansabdar of 400 and gave him a wife, but trading rights were not granted.

Answer: (d) 1, 2 and 3

1 ✔ Shantidas Jhaveri, Jain jeweller-banker of Ahmedabad. 2 ✔ Shah Jahan granted land for poshalas (Jain rest-houses). 3 ✔ Murad Bakhsh granted Palitana (1656); Aurangzeb confirmed it (1660). All correct → (d).

Answer: (d) Mulla Shah

Mulla Shah Badakhshi (Qadiri, disciple of Miyan Mir) was the teacher of Dara Shikoh; his talk on wahdat-al-wujud with Shah Jahan and Dara led Aurangzeb to condemn him.

Answer: (b) Ibrahim Shah Sharqi of Jaunpur

Sangita Shiromani (1428), a Sanskrit music compendium, was compiled under Sultan Ibrahim Shah Sharqi of Jaunpur. (Man Singh Tomar is linked to Mankutuhal.)

Answer: (c) 3, 2, 4, 1

Ashtadhyayi (Panini, ~5th–4th c. BCE) → Sushruta Samhita (core ~6th c. BCE–early CE) → Natyashastra (~200 BCE–200 CE) → Brihat Samhita (Varahamihira, 6th c. CE). Order 3, 2, 4, 1 → (c).

Answer: (b) sugar

Sugar is a solid; in solids molecules are held by the strongest intermolecular forces (here many H-bonds). Water is liquid; CCl₄ liquid (weak dispersion); helium gas (weakest). Order: sugar > water > CCl₄ > He.

Answer: (b) Bromine

At room temperature bromine is a liquid (like water). F₂ and Cl₂ are gases; I₂ is a solid. Remember: Br₂ and Hg are the only elements liquid at room temperature.

Answer: (b) Iron, Honey, Water, Air

Densities (g/cm³): iron ~7.9 > honey ~1.4 > water 1.0 > air ~0.0012. So (b).

Answer: (c) Both of them undergo sublimation

Camphor (organic) and NH₄Cl (inorganic) both sublime on heating — pass from solid to vapour directly. NH₄Cl actually dissociates to NH₃ + HCl and recombines on cooling.

Answer: (c) 5

NCERT counts five states: solid, liquid, gas, plasma and Bose–Einstein condensate. More exotic states exist, but 5 is the textbook answer.

Answer: (c) Tyndall effect

Tyndall effect: colloidal particles (1–1000 nm) scatter light, making the beam path visible. Raman = inelastic scattering by molecules; Compton = X-ray scattering by electrons; Thomson = thermoelectric effect.

Answer: (c) Tincture of iodine

Tincture of iodine (I₂ in alcohol) is a true solution. Milk = emulsion (liquid in liquid), jelly = gel, fog = aerosol (liquid in gas) — all colloids.

Answer: (d) chromatography

Dyes in ink are separated by chromatography: components move at different speeds on paper/column due to different adsorption and solubility. Evaporation leaves all dyes together.

Answer: (b) Robert Bunsen

Periodic classification: Döbereiner (triads), Newlands (octaves), Mendeleev (periodic law), also Lothar Meyer and Moseley. Bunsen is known for the burner and spectroscopy (with Kirchhoff), not periodic classification.

Answer: (a) 4.4 g

CaCO₃ → CaO + CO₂. By conservation of mass: CO₂ = 10 − 5.6 = 4.4 g → (a). Check: 100 g CaCO₃ gives 56 g CaO + 44 g CO₂.

Answer: (b) Endoplasmic reticulum having ribosomes attached to its surface

RER = rough endoplasmic reticulum: studded with ribosomes, makes proteins for secretion and membranes. SER has no ribosomes and makes lipids, detoxifies.

Answer: (a) Leucoplasts

Leucoplasts are colourless storage plastids: amyloplasts (starch), elaioplasts (oils, fats), aleuroplasts (proteins). Chromoplasts carry carotenoid pigments; chloroplasts photosynthesise.

Answer: (d) Cell active with dense cytoplasm, thin cellulose walls and prominent nuclei

Meristematic cells: actively dividing, dense cytoplasm, thin cellulose walls, prominent nuclei, no vacuoles (or very small). Thick walls belong to permanent mechanical tissues.

Answer: (d) kidney tubules.

Squamous epithelium (flat cells) lines the mouth, oesophagus, skin surface (stratified), alveoli and blood vessels. Kidney tubules are lined by cuboidal epithelium.

Answer: (a) Muscular tissue

Muscular tissue has contractile proteins (actin, myosin) that contract and relax, causing movement. Nervous tissue conducts impulses; connective tissue binds; epithelium covers.

Answer: (d) Unicellular algae, diatoms, slime moulds and protozoans

Whittaker's Protista: unicellular eukaryotes — chrysophytes (diatoms), dinoflagellates, euglenoids, slime moulds and protozoans. Bacteria, Nostoc, Anabaena and mycoplasma are prokaryotes (Monera).

Answer: (c) Species → Genus → Family → Order → Class

Ascending hierarchy: Species → Genus → Family → Order → Class → Phylum → Kingdom. Trick: 'Family' must come before 'Order'.

Answer: (a) Buccal cavity, oesophagus, stomach, small intestine, large intestine and anus

Alimentary canal: mouth (buccal cavity) → oesophagus → stomach → small intestine → large intestine → anus.

Answer: (a) Aerenchyma

Aerenchyma = parenchyma with large air spaces; it gives buoyancy and aeration to aquatic plants (Hydrilla, water hyacinth). Tracheids conduct water; sclerenchyma gives strength.

Answer: (b) Earthworm, leech and nereis

Bilateral, triploblastic, true coelom = coelomates. Annelids: earthworm, leech, Nereis → (b). Roundworms/Ascaris are pseudocoelomates; sea cucumber and sea urchin are echinoderms with radial symmetry in adults.

Answer: (c) Ampere - metre

Units of B: tesla (SI), gauss (CGS; 1 T = 10⁴ G). H (magnetising field) is in A/m. Ampere-metre (A·m) is the unit of pole strength, not field strength.

Answer: (d) The magnetic field decreases with an increase from the wire

Field of a long straight wire: B = μ₀I/(2πr). It depends on current I and distance r, not on the wire material. B ∝ 1/r: it decreases with distance from the wire.

Answer: (b) The magnetic field inside the solenoid is uniform at all the points

Inside a long solenoid B = μ₀nI, uniform at all points (parallel field lines). Near the ends it falls to about half. Textbook answer: uniform → (b).

Answer: (b) increase by four times.

B at the centre ∝ n × I. Doubling both: B′ = (2n)(2I) ∝ 4 × B → four times.

Answer: (a) 2R

R = ρl/A. Second wire: ρ(2l)/(2A) = R. In series: R + R = 2R → (a).

Answer: (a) T increases with increase in length of the pendulum

T = 2π√(l/g): T ∝ √l, so T increases with length. It is independent of the mass of the bob (and of amplitude, for small swings).

Answer: (d) It is a longitudinal wave

Infrared is an electromagnetic wave: transverse, travels through vacuum, wavelength longer than visible (700 nm – 1 mm). So 'longitudinal' is false.

Answer: (c) Radiation

Shiny (silvered) walls reflect infrared, cutting heat loss by radiation. The vacuum between walls cuts conduction and convection.

Answer: (b) 4 °C

Water has maximum density at 4 °C (anomalous expansion). That is why lakes freeze from the top and life survives below.

Answer: (d) Sound waves can propagate through vacuum

Sound is a mechanical, longitudinal wave; it needs a medium and cannot travel through vacuum. It travels faster in solids (steel ~5,000 m/s) than in air (~343 m/s).

Answer: (a) Singapore

IMD World Competitiveness Ranking 2019: Singapore 1st, Hong Kong 2nd, USA 3rd; India was 43rd.

Answer: (b) Papua New Guinea

UN (International Year of Indigenous Languages, 2019): Papua New Guinea has the most living languages — about 840.

Answer: (c) Science and Technology

Shanti Swarup Bhatnagar Prize (CSIR, from 1958) honours outstanding Indian scientists under 45 in science and technology.

Answer: (a) Shaliza Dhami

Wing Commander Shaliza Dhami became the IAF's first woman Flight Commander of a flying unit (Chetak helicopter unit, Hindon, 2019).

Answer: (c) 15

CARICOM (Caribbean Community, 1973, HQ Georgetown, Guyana) has 15 member states and 5 associate members.

Answer: (b) Pandit Jasraj

The IAU named minor planet 2006 VP32 as 'Panditjasraj' (2019) — first Indian musician so honoured.

Answer: (c) K K Birla Foundation.

Saraswati Samman (1991) is given by the K.K. Birla Foundation for an outstanding literary work in any Indian language. The foundation also gives the Vyas Samman and Bihari Puraskar.

Answer: (d) Bangladesh

India beat Bangladesh 2–1 in the final of the SAFF U-18 Championship 2019 (Kathmandu).

Answer: (c) September 26

International Day for the Total Elimination of Nuclear Weapons: 26 September (UN, observed since 2014).

Answer: (c) Nepal

Surya Kiran = India–Nepal army exercise. Others: Sampriti (Bangladesh), Mitra Shakti (Sri Lanka), Hand-in-Hand (China), Nomadic Elephant (Mongolia).