UPSC 2018 Previous Year GK Questions with Answers

The correct answer is B, 1, 2 and 4. For small swings the time period is T = 2π√(L/g), which contains the length and gravity but neither the mass nor the amplitude.

Statement 1 is correct: T grows with the square root of length, so a pendulum four times longer takes twice as long per swing. Statement 2 is correct: T falls as g rises, so a pendulum clock runs slow on a hill or on the Moon, where g is smaller. Statement 3 is wrong: the mass of the bob cancels out of the equation, so a heavy and a light bob on equal strings swing together. Statement 4 is correct: for small amplitudes the period is the same however wide the swing, which Galileo noticed and which makes pendulum clocks possible.

A is wrong: it includes statement 3 and leaves out statement 4.

C is wrong: it includes the wrong statement 3 and drops statement 1.

D is wrong: it drops statement 2, though g appears in the formula.

Exam tip: T = 2π√(L/g); independent of mass and (small) amplitude; seconds pendulum ≈ 1 m long, T = 2 s.

The correct answer is B, Active transport of ions and small molecules across cell membrane against concentration gradient requires energy. Moving a substance from low to high concentration is uphill work, and the cell pays for it with ATP.

In active transport, carrier proteins called pumps in the membrane use energy from ATP to push ions such as K+ and nitrate into root hair cells, even when the soil holds far less of them than the cell does. Diffusion and osmosis, by contrast, are passive: substances move down their own gradient, from high to low concentration, without spending energy.

A is wrong: diffusion is passive and needs no energy from the cell.

C is wrong: moving anything against a concentration gradient always needs energy; the cell cannot do it for free.

D is wrong: plant cells do move ions across membranes all the time, through channels, carriers and pumps; that is how roots take up minerals.

Exam tip: down the gradient = diffusion or osmosis, no energy; up the gradient = active transport, needs ATP.

The correct answer is C, Proteins in mammalian cells are synthesized in rough endoplasmic reticulum. The RER is studded with ribosomes, the actual sites where amino acids are joined into proteins.

Ribosomes read the message carried by mRNA and link amino acids in the right order. Those attached to the rough endoplasmic reticulum make proteins meant for membranes or for export, such as enzymes and hormones; the new chains enter the RER, fold, and then move on in vesicles. Free ribosomes in the cytoplasm make proteins used inside the cell.

A is wrong: the cell membrane only controls what enters and leaves; it has no protein-making machinery.

B is wrong: food proteins are digested into amino acids, which are absorbed and then built into the body's own proteins inside cells.

D is wrong: the Golgi apparatus modifies, packages and dispatches proteins made in the RER; it does not make them.

Exam tip: ribosome (on RER) = protein synthesis; Golgi = packaging and secretion; SER = lipid synthesis.

The correct answer is A, 2 and 1. For a 4d orbital, n = 4 and l = 2, which gives l = 2 angular nodes and n − l − 1 = 1 radial node.

A node is a region where the probability of finding the electron is zero. Angular nodes are planes or cones through the nucleus, and their number equals the azimuthal quantum number l. Radial nodes are spherical shells, and their number is n − l − 1. The total number of nodes is always n − 1. For 4d: l = 2 for any d orbital, so 2 angular nodes; radial nodes = 4 − 2 − 1 = 1; total = 3, which equals n − 1. In the same way 3d has 2 angular and 0 radial nodes, and 2s has 0 angular and 1 radial node.

B is wrong: it reverses the two values.

C is wrong: 3 angular nodes belong to an f orbital (l = 3), not a d orbital.

D is wrong: 4 angular nodes would need l = 4, a g orbital, and the total of 4 exceeds n − 1 = 3.

Exam tip: angular nodes = l, radial nodes = n − l − 1, total nodes = n − 1.

The correct answer is B, lowers the boiling point of the liquid. A liquid boils when its vapour pressure equals the pressure above it, so less outside pressure means boiling starts at a lower temperature.

As a liquid is heated, its vapour pressure rises. Boiling begins at the temperature where this vapour pressure matches the external pressure. At sea level, with about 101.3 kPa of pressure, water boils at 100 °C. High in the mountains the air pressure is lower, so water boils at around 70 to 90 °C, which is too cool to cook rice or pulses quickly. A pressure cooker does the opposite: it raises the pressure to about twice the normal value, so water boils near 120 °C and food cooks faster.

A is wrong: raising the pressure, not lowering it, raises the boiling point.

C is wrong: boiling point depends directly on the outside pressure.

D is wrong: with a lower boiling point the liquid reaches boiling sooner, not later.

Exam tip: low pressure, low boiling point (hills); high pressure, high boiling point (pressure cooker).

The correct answer is A, 1 and 3. A compound microscope uses two convex lenses, and its magnification depends on the tube length.

The objective is a convex lens of very short focal length that forms a real, enlarged image of the specimen. The eyepiece is also a convex lens and works like a magnifying glass on that image. The total magnification is roughly (L/fo) × (D/fe), where L is the tube length, D is 25 cm, the least distance of distinct vision, and fo and fe are the focal lengths of the objective and eyepiece. So a longer tube gives more magnification, while a longer focal length gives less.

B is wrong: statement 3 is true, but statement 1 is also true, so 3 alone is incomplete.

C is wrong: statement 4 is false, because the eyepiece is convex, not concave.

D is wrong: statement 2 is false, since magnification falls as the objective's focal length rises, and statement 4 is false as well.

Exam tip: microscope = two convex lenses, objective of short focal length; telescope objective has a long focal length.

The correct answer is C, total internal reflection. Light inside the fibre strikes the boundary at more than the critical angle, so it is reflected back again and again instead of escaping.

An optical fibre has a glass core surrounded by cladding of slightly lower refractive index. Total internal reflection happens when light travels from a denser to a rarer medium and the angle of incidence is greater than the critical angle. Each time the signal meets the core-cladding boundary it is fully reflected, so it zigzags along the fibre with very little loss, even around gentle bends. This is why fibres carry internet and telephone data over long distances and are used in endoscopes.

A is wrong: interference is the overlapping of waves to form bright and dark bands.

B is wrong: scattering spreads light out, as in the blue sky, and is a source of loss in a fibre.

D is wrong: refraction lets light pass out of the core; the fibre works because light does not refract out.

Exam tip: two conditions for total internal reflection are denser to rarer medium and angle above the critical angle; examples are optical fibre, sparkling diamond and mirage.

The correct answer is D, 1, 2 and 3. All three are adaptations of desert plants (xerophytes) that cut down water loss through transpiration.

Plants lose most of their water through the leaves, so desert plants change their leaves to save it. A thick waxy cuticle makes the leaf surface hard and waterproof, as in the oleander and many succulents. Small leaves expose less surface to the hot, dry air, as in acacia and tamarisk. In cacti and some euphorbias the leaves are reduced to spines or thorns, and the green fleshy stem takes over photosynthesis and stores water. Sunken stomata and fewer stomata are other such features.

A is wrong because it leaves out hard, waxy leaves.

B is wrong because tiny leaves are only one of the three adaptations.

C is wrong because thorns are not the only change seen in desert plants.

Exam tip: cactus = leaves turned into spines, stem does photosynthesis; xerophytes = waxy cuticle, small leaves, sunken stomata.

The correct answer is B, 2 only. The first Leader of the Opposition in the Lok Sabha was recognised in 1969, when Ram Subhag Singh of the Congress (O) was given the post.

Statement 1 is wrong: the Swatantra Party was founded only in 1959, years after the first Lok Sabha (1952–57); the largest opposition party then was the Communist Party of India. Statement 3 is wrong: the practice, based on the Speaker's direction, is that a party needs at least one-tenth of the House's strength, that is 55 members, not 75. The Salary and Allowances of Leaders of Opposition in Parliament Act, 1977 later gave the post statutory recognition.

A is wrong because both statements 1 and 3 are false.

C is wrong because the minimum is one-tenth of the House (55), not 75.

D is wrong because only statement 2 is true.

Exam tip: first LoP recognised in 1969; the one-tenth rule means 55 seats in a 543-member Lok Sabha.

The correct answer is A, the Arabian Sea exhibits a high rate of evaporation and a low influx of fresh water. Salinity rises where water leaves as vapour and falls where fresh water is added. The air over the Arabian Sea is dry and hot, evaporation is heavy, rainfall is modest and the only large river reaching it is the Indus, so the salt that stays behind keeps surface salinity around 36 parts per thousand. The Bay of Bengal gets the Ganga, Brahmaputra, Mahanadi, Godavari and Krishna along with very heavy monsoon rain, and all that fresh water dilutes it to about 33 parts per thousand. Option B is wrong because the Arabian Sea is in fact the deeper of the two basins, and depth by itself does not decide salinity. Option C is wrong because the Bay of Bengal is the more enclosed of the two, yet it is the less saline. Option D is wrong because the Arabian Sea receives less rainfall, and rain lowers salinity instead of raising it. Exam tip: evaporation raises salinity; river water and rainfall lower it.

The correct answer is B, Emerald. Emerald is the deep green variety of the mineral beryl, a beryllium aluminium silicate, so beryllium is part of its very formula. Traces of chromium, and sometimes vanadium, give the stone its green colour. Beryl is the chief ore of beryllium, a light, stiff metal used in X-ray windows, aerospace alloys and nuclear reactors; aquamarine is the pale blue variety of the same mineral. Option A is wrong because topaz is an aluminium silicate carrying fluorine and hydroxyl groups, with no beryllium in it. Option C is wrong because ruby is corundum, that is aluminium oxide, which turns red because of chromium impurity. Option D is wrong because blue sapphire is the same corundum, coloured blue by traces of iron and titanium. So ruby and sapphire are two colours of one mineral, while emerald belongs to a different family altogether. Exam tip: emerald = beryl (beryllium); ruby and sapphire = corundum (aluminium oxide).

The correct answer is D, Dual Government. A dual government, one at the centre and one in the units, is the common feature of every federation, so India and the USA do not differ on this point. Both countries divide powers between a national government and state governments through a written constitution, and both let courts settle disputes about that division. The other three features are exactly where the two systems part company, because India has a federation with a strong unitary bias. Option A is wrong because every American state sends two members to the Senate regardless of size, while seats in the Rajya Sabha are allotted according to a state’s population, so representation is unequal. Option B is wrong because an American citizen is a citizen of both the Union and a state, while India gives only single citizenship. Option C is wrong because the USA has separate federal and state courts, while India has one integrated judiciary headed by the Supreme Court. Exam tip: India — single citizenship, integrated judiciary, unequal Rajya Sabha seats.

The correct answer is B, 2 only. The second statement describes the two bodies correctly while the first gets the origin of the Board wrong, so only statement 2 can be accepted. The National Green Tribunal is a specialised court set up by the National Green Tribunal Act of 2010 to decide disputes under the environmental laws quickly, and it does take such cases away from the ordinary courts. The Central Pollution Control Board works on the quality of air and water, promoting the cleanliness of streams and wells, laying down standards and running the national monitoring network. Statement 1 is wrong because the Board was also created by a statute, the Water (Prevention and Control of Pollution) Act of 1974, and not by an executive order; the Air Act of 1981 later added to its work. A and C are wrong because each accepts statement 1. D is wrong because statement 2 is sound. Exam tip: CPCB 1974 under the Water Act, NGT 2010 under its own Act.

The correct answer is D, Kishangarh school. Bani Thani was painted by Nihal Chand in the eighteenth century at Kishangarh in Rajasthan, under Raja Savant Singh, who wrote devotional poetry under the name Nagari Das. The figure has an elongated face, a long neck, a sharply arched eyebrow and a curving eye, and this stylised female type became the mark of the school. The painting is often called the Mona Lisa of India, and Kishangarh work usually sets its lovers beside lotus filled lakes.

Option A, the Bundi school, is recognised by dense blue green vegetation, water and animal life, not by this female type. Option B, the Jaipur or Amber school, worked under strong Mughal influence on large portraits. Option C, the Kangra school, is a Pahari style from the hills, delicate and lyrical, famous for the Gita Govinda series, and geographically far from Rajasthan.