UPSC 2021 Previous Year GK Questions with Answers

The correct answer is C, Oxbow lake. When a river cuts across the narrow neck of a loop and silt seals both ends, the old loop is left behind as a curved lake. Meanders form in the middle and lower course, where a river flows slowly over flat land, cutting its outer bank and building up its inner bank. Over time the neck of a loop grows thinner until a flood breaks through it and the river takes the shorter path. The abandoned bend is shaped like the U-shaped collar of an ox's yoke, which gives the lake its name; Kanwar Lake (Kabar Tal) in Bihar was left behind in this way by the Burhi Gandak. Option A is wrong because potholes are round holes drilled into a rocky bed by pebbles swirling in a fast upper-course stream. Option B is wrong because levees are raised banks of silt dropped along the river during floods. Option D is wrong because a flood plain is the wide flat land built by repeated floods, not a cut-off loop. Exam tip: meander plus cut-off gives an oxbow lake, a mark of the river's old stage.

The correct answer is A, Nizam Shahis : Bijapur. The Nizam Shahis ruled from Ahmadnagar; Bijapur belonged to the Adil Shahis. The Bahmani Sultanate, founded in 1347 by Alauddin Hasan Bahman Shah, broke up in the late 15th and early 16th centuries into five Deccan Sultanates: Ahmadnagar, Bijapur, Golconda, Bidar and Berar. Four of them joined hands to defeat Vijayanagara at the Battle of Talikota in 1565, while Berar stayed away. Each dynasty is named after the title of its founder, which makes the pairs easy to link. Option B is correctly matched because the Barid Shahis ruled Bidar, the last Bahmani capital. Option C is correctly matched because the Qutb Shahis ruled Golconda, famous for its fort and its diamond trade. Option D is correctly matched because the Imad Shahis ruled Berar, which Ahmadnagar annexed in 1574. Exam tip: Nizam Shahi Ahmadnagar, Adil Shahi Bijapur, Qutb Shahi Golconda, Barid Shahi Bidar, Imad Shahi Berar.

The correct answer is C, 3 only. Members of the State Legislative Councils have no vote in the presidential election. Under Article 54, the President is chosen by an electoral college of the elected members of both Houses of Parliament and the elected members of the Legislative Assemblies of the States. The 70th Amendment Act, 1992 added the elected members of the Assemblies of Delhi and Puducherry. Voting follows proportional representation by the single transferable vote, and the ballot is secret. Nominated members of any House and all members of Legislative Councils stay out, though nominated members of Parliament do vote for the Vice-President. Options A and D are wrong because the elected members of the Rajya Sabha and of the State Assemblies are both part of the electoral college. Option B is wrong because it leaves out the elected Assembly members too, when they cast about half of the total vote value. Exam tip: only elected members of Parliament and the Assemblies vote for the President; Council members and nominated members never do.

The correct answer is C, 1 and 3 only. The cooking temperature is set by the pressure inside the cooker, and that pressure is fixed by the weight sitting on the vent and the area of the hole under it. The boiling point of water rises with pressure. In an open pan water boils at 100°C, but when steam is trapped, pressure builds up until it can lift the weight, the whistle, off the vent. Pressure is force divided by area, so a heavier weight or a smaller hole means a higher pressure before steam escapes, and water then boils at about 120°C, which is why food cooks faster. Statement 2 is wrong because a bigger flame only makes the water boil and the whistle blow sooner; once steam escapes, the temperature stays at the boiling point for that pressure, and extra heat just makes more steam. Statements 1 and 3 are right for the reason above. So options A, B and D, which include statement 2, are wrong. Exam tip: higher pressure means a higher boiling point; the flame changes the speed, not the temperature.

The correct answer is A, it is dipolar in nature. Water is called the universal solvent because its molecule is polar: the oxygen end carries a partial negative charge and the two hydrogen ends carry partial positive charges. The molecule is bent at an angle of about 104.5°, so these charges do not cancel out. When a salt such as sodium chloride is put in water, the negative oxygen ends surround the sodium ions and the positive hydrogen ends surround the chloride ions, pulling the crystal apart; this is called hydration. Water also forms hydrogen bonds with polar substances such as sugar and alcohol, which is why they dissolve easily, while non-polar oil does not. Option B is wrong because water is in fact a poor conductor of heat, and heat conduction has nothing to do with dissolving. Option C is wrong because high specific heat explains why water warms up slowly, not why it dissolves things. Option D is wrong because being an oxide of hydrogen does not by itself make a liquid a good solvent. Exam tip: polar water dissolves polar and ionic substances, because like dissolves like.

The correct answer is C, 1, 3 and 5 only. Earthworms, millipedes and woodlice feed on dead plant and animal matter, called detritus, so they are detritivores. Detritivores break dead leaves and bodies into small pieces, which speeds up the work of decomposers such as bacteria and fungi that finish the breakdown and return nutrients to the soil. Earthworms eat decaying leaves and soil, millipedes chew leaf litter on the forest floor, and woodlice are small land crustaceans that live under logs and eat rotting wood. The key difference is that detritivores swallow detritus, while decomposers digest it outside their bodies. Jellyfish (2) are wrong because they are carnivores that sting and eat plankton and small fish. Seahorses (4) are wrong because they suck in tiny live crustaceans. So options A, B and D, which include jellyfish or seahorses, are wrong. Exam tip: earthworms, millipedes, woodlice and dung beetles are detritivores; bacteria and fungi are decomposers.

The correct answer is A, Carbon captured by oceans and coastal ecosystems. Blue carbon is the carbon stored by marine and coastal ecosystems, especially mangroves, salt marshes and seagrass meadows. These plants take in carbon dioxide, and because their waterlogged soils have little oxygen, dead matter decays slowly and the carbon stays locked in the sediment for hundreds or even thousands of years. Area for area, they can store several times more carbon than tropical forests, which is why protecting the Sundarbans and India's seagrass beds counts as climate action. When these habitats are cleared, the stored carbon goes back into the air. Option B is wrong because carbon held in forest biomass and farm soils is called green carbon. Option C is wrong because carbon in petroleum and natural gas is fossil carbon, which is released as carbon dioxide when burnt. Option D is wrong because carbon dioxide in the air is simply atmospheric carbon, not stored carbon. Exam tip: blue carbon means coasts and oceans, green carbon means forests and soils.

The correct answer is C, Increase in the banking habit of the people. When people keep more of their money in banks instead of as cash, banks can lend more, so each rupee of reserve money creates more money in the economy. The money multiplier is the ratio of broad money (M3) to reserve money (M0). It depends on two leakages: the cash people hold, measured by the currency–deposit ratio, and the reserves banks must keep, measured by the reserve ratios. The smaller the leakage, the bigger the multiplier. A stronger banking habit lowers the currency–deposit ratio, so more of each rupee returns to banks and is lent again. Option A is wrong because a higher Cash Reserve Ratio makes banks park more money with the RBI, which lowers the multiplier. Option B is wrong because a higher Statutory Liquidity Ratio also locks up more of banks' funds and cuts lending. Option D is wrong because population by itself does not change how much of each deposit banks can lend. Exam tip: more money in banks means a bigger multiplier; a higher CRR or SLR means a smaller one.

The correct answer is B, fissure volcanic rock. Black cotton soil, or regur, formed from the weathering of the Deccan Trap basalt, lava that poured out through long cracks in the crust about 65 million years ago. This fissure eruption spread layer after layer of basalt over Maharashtra, western Madhya Pradesh, Gujarat and parts of Karnataka, Telangana and Andhra Pradesh, and the soil is found mainly on this plateau. It is rich in iron, lime, magnesium and potash but poor in nitrogen, phosphorus and organic matter, and its dark colour comes from titaniferous magnetite and humus. It holds moisture well, swells when wet and cracks deeply when dry, so it is said to 'plough itself', and it suits cotton. Option A is wrong because brown forest soil is itself a soil type, not the parent rock of regur. Option C is wrong because granite and schist weather mainly into red soils. Option D is wrong because shale and limestone are sedimentary rocks, not the source of the Deccan soils. Exam tip: regur means Deccan basalt, cotton and self-ploughing cracks.

The correct answer is A, Dholavira. This Harappan city in the Rann of Kutch, Gujarat, is famous for its dams, channels and chain of stone reservoirs. Dholavira stands on Khadir Bet island between two seasonal streams, the Manhar and the Mansar. Its people built check dams across the streams, led the water through channels and stored it in large rock-cut reservoirs around the city, a clever answer to a very dry climate. The site, excavated by R.S. Bisht, also has a signboard of ten large Harappan letters, and it became a UNESCO World Heritage Site in 2021. Option B is wrong because Kalibangan in Rajasthan is known for its ploughed field and fire altars. Option C is wrong because Rakhigarhi in Haryana is known as one of the largest Harappan sites, not for water works. Option D is wrong because Ropar in Punjab is known for a burial of a dog with its master. Exam tip: Dholavira means reservoirs and a signboard; Lothal means a dockyard.

The correct answer is B, Legal right available to any person. Since 1978 property is a constitutional right under Article 300A, and it protects every person, not only citizens. The 44th Amendment Act, 1978 deleted Article 19(1)(f) and Article 31 from Part III and added Article 300A, which says no person shall be deprived of his property save by authority of law. So the State can take property only through a valid law, and a company or a foreigner can also claim this protection. Because it is outside Part III, a person cannot go straight to the Supreme Court under Article 32 for it; the remedy is the High Court under Article 226 or an ordinary suit. Option A is wrong because the word 'person' in Article 300A covers non-citizens too. Option C is wrong because property stopped being a Fundamental Right in 1978. Option D is wrong because it is still a constitutional and legal right. Exam tip: 44th Amendment, property moved from Part III to Article 300A in Part XII.

The correct answer is C, Article 21. The Supreme Court has read privacy into the right to life and personal liberty. In Justice K.S. Puttaswamy v. Union of India (2017), a nine-judge bench unanimously held that privacy is a fundamental right, protected mainly as part of Article 21 and also by the other freedoms in Part III. The same bench overruled the older rulings in M.P. Sharma (1954) and Kharak Singh (1962), which had said the Constitution gives no right to privacy. The case began as a challenge to the Aadhaar scheme, which makes it easy to remember. Option A is wrong because Article 15 bars discrimination on grounds of religion, race, caste, sex or place of birth. Option B is wrong because Article 19 lists six freedoms such as speech and movement, and privacy is not one of them. Option D is wrong because Article 29 protects the language, script and culture of minorities. Exam tip: privacy, like shelter, health and a speedy trial, is a right the courts have read into Article 21.