Science & Technology

Correct answer: (C) Pregnancy & child birth

An obstetrician is a doctor specialising in pregnancy, childbirth and the postpartum period.

Correct answer: (C) Plutonium

Plutonium-238 is the radioactive element used as the power source in nuclear (radioisotope) heart pacemakers.

Correct answer: (B) 14/6 C

Carbon-14 (¹⁴₆C), a radioactive isotope, is used in radiocarbon dating to determine the age of archaeological remains.

Correct answer: (B) 32 °F

Pure water freezes at 0°C, which equals 32°F on the Fahrenheit scale.

Correct answer: (B) AIDS antibodies

ELISA (Enzyme-Linked Immunosorbent Assay) detects antibodies in blood; its best-known use is as the screening test for HIV/AIDS antibodies. It relies on an enzyme-linked antigen-antibody colour reaction.

Correct answer: (C) Salvinia

Salvinia is a free-floating aquatic fern (a water fern), whereas Adiantum, Dryopteris and Equisetum are terrestrial pteridophytes.

Correct answer: (A) Radioactivity

The Curie (Ci) is a unit of radioactivity, defined as 3.7×10^10 disintegrations per second, named after Marie and Pierre Curie.

Correct answer: (A) Peripatus

Peripatus (velvet worm) is called a 'living fossil' because it is a connecting link between annelids and arthropods, showing characters of both and surviving almost unchanged over geological time.

Correct answer: (D) K

Vitamin K is essential for the synthesis of clotting factors (like prothrombin) in the liver, so it helps blood coagulation.

Correct answer: (D) None of the above

The human ovum is a haploid gamete carrying only 23 chromosomes, not 36/46/48, so the correct answer is 'None of the above'.

Correct answer: (C) Fish

The seahorse (genus Hippocampus) is a bony fish that breathes through gills and has fins, despite its horse-like head.

Correct answer: (B) Gamma rays

Gamma rays have the shortest wavelength and highest frequency in the electromagnetic spectrum, and since energy is proportional to frequency (E=hf), they carry the maximum energy.

Correct answer: (D) Butane

Liquefied Petroleum Gas (LPG) is chiefly a mixture dominated by butane (with some propane), used as domestic cooking fuel.

Correct answer: (C) Mitochondria

The mitochondrion is called the 'powerhouse of the cell' because it generates most of the cell's ATP through cellular respiration.

Correct answer: (A) Iron

Haemoglobin contains iron (in the haem group), which binds oxygen for transport in the blood.

Correct answer: (C) Lens

The crystalline lens has the highest refractive index (about 1.41) among the eye's optical components.

Correct answer: (D) Chlorofluorocarbon

Chlorofluorocarbons (CFCs) have been the common refrigerant gases used in refrigerators.

Correct answer: (C) Copper and Tin

Bronze is an alloy of copper and tin.

Correct answer: (A) F-

O2- has 10 electrons (8 + 2). F- also has 10 electrons (9 + 1), so the two are isoelectronic.

Correct answer: (A) Bird

Ornithology is the branch of zoology dealing with the study of birds.

Correct answer: (D) Toad

The toad is an amphibian and is cold-blooded (poikilothermic); hen, tiger and bat are warm-blooded.

Correct answer: (A) Tobacco

Tobacco was the first transgenic (genetically engineered) crop, developed in 1983.

Correct answer: (B) Current

A step-down transformer reduces voltage; since power is conserved, lowering the voltage increases the current in the secondary coil.

Correct answer: (D) V²/r

In uniform circular motion the speed is constant but direction changes, giving a centripetal acceleration directed to the centre of magnitude V²/r.

Correct answer: (B) Zymase

Yeast ferments sugar to alcohol and carbon dioxide chiefly through the enzyme zymase, a complex it produces.

Correct answer: (C) √3 : √2

For an ideal gas the rms speed is sqrt(3RT/M) and the most probable speed is sqrt(2RT/M), so their ratio is sqrt(3):sqrt(2). This ordering (v_mp < v_avg < v_rms) is a standard result of Maxwell's speed distribution.

Correct answer: (A) 1 : 12

The hour hand completes one revolution in 12 hours while the minute hand does so in 1 hour, so their angular (velocity) ratio is 1:12. The minute hand is twelve times faster.

Correct answer: (C) insulator

At absolute zero (0 K) pure (intrinsic) silicon has no thermally excited charge carriers, so its valence band is full and conduction band empty, making it behave as a perfect insulator. It conducts only when heated or doped.

Correct answer: (B) 50 cm, convex

Focal length = 1/power = 1/2.0 = 0.5 m = 50 cm. A positive power (+2.0 D) means a converging lens, i.e. convex.

Correct answer: (C) Diffraction

The rainbow colours seen on a CD arise from diffraction: the closely spaced data tracks act as a reflection diffraction grating that splits white light into its component colours.

Correct answer: (A) SARS-CoV-2

The virus causing COVID-19 was officially named SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) by the ICTV; 'COVID-19' is the name of the disease, not the virus.

Correct answer: (B) the Mars

NASA's Perseverance rover landed in Jezero Crater on Mars on 18 February 2021, carrying the Ingenuity helicopter, to search for signs of ancient microbial life and collect rock samples.

Correct answer: (B) high k and low δ

Diamond has very high thermal conductivity (its rigid covalent lattice transmits lattice vibrations/phonons extremely efficiently) but very low electrical conductivity, because all valence electrons are locked in covalent bonds leaving none free to carry current - so high k and low sigma.

Correct answer: (C) 6V

When cells are in series, each wrongly connected (reversed) cell subtracts twice its emf from the total. Total for 10 cells = 10V; reversing 2 cells subtracts 2 x (2 x 1V) = 4V, giving 10 - 4 = 6V.

Correct answer: (B) Bharati

'Bharati' is India's third Antarctic research station, commissioned in March 2012. Dakshin Gangotri (1983) and Maitri (1989) were the earlier stations.

Correct answer: (B) Pascal's law

The hydraulic press works on Pascal's law: pressure applied to a confined fluid is transmitted equally in all directions, so a small force on a small piston produces a large force on a larger piston.

Correct answer: (C) decreases

Standing up raises the person's centre of mass, shortening the effective length L of the pendulum. Since the time period T = 2 pi root(L/g), a smaller L decreases the period.

Correct answer: (D) Solid CO2

Dry ice is solid carbon dioxide (CO2); it sublimes directly from solid to gas without melting, which is why it is used for refrigeration and fog effects.

Correct answer: (D) convection currents are set up.

The freezer is placed at the top so that the cooled, denser air sinks and warmer air rises, setting up convection currents that circulate and cool the whole cabinet.

Correct answer: (C) longitudinal and transverse

Water surface waves produced by a moving motor boat are of the combined type: water particles move in circular/elliptical paths, so the motion has both transverse (up-down) and longitudinal (back-forth) components. Hence they are both longitudinal and transverse.

Correct answer: (D) Sn and Pb

Solder used to join metal parts is a fusible alloy of tin (Sn) and lead (Pb), valued for its low melting point which lets it flow and bond without damaging the joined pieces.

Correct answer: (C) Greenhouse

A solar cooker works on the greenhouse principle: the glass cover lets in short-wave sunlight but traps the re-radiated long-wave infrared heat inside, raising the internal temperature to cook food.

Correct answer: (B) increase by about 11%

Power P = V^2/R and resistance R is proportional to length. Reducing length by 10% gives R' = 0.9R, so P' = V^2/(0.9R) = P/0.9 ≈ 1.111P, an increase of about 11%.

Correct answer: (B) Science and Technology

The Shanti Swarup Bhatnagar Prize, instituted by CSIR and named after its founder-director, is India's top honour for outstanding research in science and technology, given annually to scientists under 45. It is not a peace, medicine or economics award.

Correct answer: (A) Nipah

An ICMR study reported finding antibodies to the Nipah virus in fruit bats (Rousettus and Pteropus) sampled from a cave at Mahabaleshwar, Maharashtra, flagging the risk of a future Nipah spillover. Nipah, not Ebola or Zika, was the virus detected.

Correct answer: (D) It will remain same.

The water the passengers drink leaves the tank but is now carried inside the floating boat, which sinks a little deeper and displaces exactly that much extra water; the two effects cancel, so the tank's water level stays the same.

Correct answer: (D) √6 times slower.

A pendulum's period T = 2π√(L/g), so it varies inversely with √g. The Moon's gravity is about g/6, making √g smaller by √6, so T becomes √6 times larger and the clock runs √6 times slower.

Correct answer: (A) Sulphur

Cutting an onion releases sulphur-containing compounds that enzymes convert into syn-propanethial-S-oxide, a volatile gas that irritates the eyes and triggers tears; the key element is sulphur.

Correct answer: (C) 2k

Spring constant is inversely proportional to length. Cutting a spring into two equal halves halves each length, so each half becomes twice as stiff, giving a spring constant of 2k.

Correct answer: (D) 2v1v2 / (v1 + v2)

When equal distances are covered at different speeds, the average speed is the harmonic mean: total distance over total time = 2d / (d/v1 + d/v2) = 2v1v2/(v1+v2).

Correct answer: (C) 1 : 4

The Moon's diameter is about 3,474 km and the Earth's about 12,742 km, giving a ratio of roughly 1:3.67, which is nearest to 1:4 among the options.

Correct answer: (A) heavy body has greater momentum.

Momentum p = √(2m·KE). For equal kinetic energy, p increases with mass, so the heavier body has the greater momentum.

Correct answer: (D) Jiffy

Light year, parsec and furlong are all units of length/distance; a 'jiffy' is a unit of time (a very short time interval), so it is not a unit of distance.

Correct answer: (C) dimensional change in material

A dilatometer measures dimensional (volume or length) changes in a material caused by temperature or other conditions, i.e. thermal expansion/contraction, not electrical, mechanical or thermal energy directly.