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UPSC Prelims 2024 — GS Paper I

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UPSC Prelims 2024 — GS Paper I — solved practice questions

8 UPSC Previous Year Papers questions with step-by-step solutions. Attempt each, then reveal the answer.

  1. Q1medium

    Consider the following statements : Statement-I : The atmosphere is heated more by incoming solar radiation than by terrestrial radiation. Statement-II : Carbon dioxide and other greenhouse gases in the atmosphere are good absorbers of long wave radiation. Which one of the following is correct in respect of the above statements ?

    • ABoth Statement-I and Statement-II are correct and Statement-II explains Statement-I
    • BBoth Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
    • CStatement-I is correct, but Statement-II is incorrect
    • DStatement-I is incorrect, but Statement-II is correct
    Show answer & solution

    Correct answer: (D) Statement-I is incorrect, but Statement-II is correct

    Statement-I is incorrect: the atmosphere is heated mainly by terrestrial (long-wave) radiation, not directly by incoming solar (short-wave) radiation. Most incoming solar radiation passes through the atmosphere and heats the Earth's surface, which then re-radiates heat as long-wave radiation that the air absorbs. Statement-II is correct because CO2 and other greenhouse gases are good absorbers of long-wave (terrestrial) radiation, which is exactly why the surface, and not incoming sunlight, warms the air. Hence only Statement-II is correct, giving option D.

  2. Q2medium

    Consider the following statements : Statement-I : Thickness of the troposphere at the equator is much greater as compared to poles. Statement-II : At the equator, heat is transported to great heights by strong convectional currents. Which one of the following is correct in respect of the above statements ?

    • ABoth Statement-I and Statement-II are correct and Statement-II explains Statement-I
    • BBoth Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
    • CStatement-I is correct, but Statement-II is incorrect
    • DStatement-I is incorrect, but Statement-II is correct
    Show answer & solution

    Correct answer: (A) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I

    Both statements are correct and the second explains the first. The troposphere is about 16-18 km thick at the equator but only around 8-9 km at the poles. This is because intense equatorial heating drives strong convection currents that carry heat and turbulence to greater heights, pushing the tropopause higher. So Statement-II is the direct cause of Statement-I, making option A correct.

  3. Q3easy

    Consider the following : (1) Pyroclastic debris (2) Ash and dust (3) Nitrogen compounds (4) Sulphur compounds. How many of the above are products of volcanic eruptions ?

    • AOnly one
    • BOnly two
    • COnly three
    • DAll four
    Show answer & solution

    Correct answer: (D) All four

    All four are products of volcanic eruptions. Eruptions eject pyroclastic debris (rock fragments/bombs), fine ash and dust, and release gases including sulphur compounds (mainly SO2 and H2S) and nitrogen compounds. Volcanic gases are dominated by water vapour, CO2 and sulphur, but nitrogen and its compounds are also emitted, so the count is all four, giving option D.

  4. Q4hard

    Which of the following is/are correct inference/inferences from isothermal maps in the month of January ? (1) The isotherms deviate to the north over the ocean and to the south over the continent. (2) The presence of cold ocean currents, Gulf Stream and North Atlantic Drift make the North Atlantic Ocean colder and the isotherms bend towards the north. Select the answer using the code given below :

    • A1 only
    • B2 only
    • CBoth 1 and 2
    • DNeither 1 nor 2
    Show answer & solution

    Correct answer: (A) 1 only

    Only inference 1 is correct. In January (Northern winter) the oceans are warmer than the cold continents, so isotherms bend north (poleward) over oceans and south (equatorward) over continents, confirming statement 1. Statement 2 is wrong on two counts: the Gulf Stream and North Atlantic Drift are warm currents (not cold), and they make the North Atlantic warmer, causing isotherms to bend north over that ocean because of warmth, not cold. Hence only 1 is correct, giving option A.

  5. Q5easy

    Which of the following countries are well known as the two largest cocoa producers in the world ?

    • AAlgeria and Morocco
    • BBotswana and Namibia
    • CCôte d'Ivoire and Ghana
    • DMadagascar and Mozambique
    Show answer & solution

    Correct answer: (C) Côte d'Ivoire and Ghana

    Cote d'Ivoire (Ivory Coast) and Ghana are the world's two largest cocoa producers, together accounting for roughly 60% of global cocoa output. Both are West African nations with climates ideal for cacao cultivation. The other pairs (North African, southern African and Indian Ocean countries) are not major cocoa producers, so option C is correct.

  6. Q6hard

    With reference to the Himalayan rivers joining the Ganga downstream of Prayagraj from West to East, which one of the following sequences is correct ?

    • AGhaghara – Gomati – Gandak – Kosi
    • BGomati – Ghaghara – Gandak – Kosi
    • CGhaghara – Gomati – Kosi – Gandak
    • DGomati – Ghaghara – Kosi – Gandak
    Show answer & solution

    Correct answer: (B) Gomati – Ghaghara – Gandak – Kosi

    Moving downstream of Prayagraj (Allahabad) from west to east, the Himalayan tributaries join the Ganga in the order Gomati, Ghaghara, Gandak, Kosi. The Gomati joins first near Ghazipur/Saidpur, followed by the Ghaghara, then the Gandak near Patna, and finally the Kosi in Bihar before the river enters West Bengal. This west-to-east sequence matches option B.

  7. Q7medium

    Consider the following statements : Statement-I : Rainfall is one of the reasons for weathering of rocks. Statement-II : Rain water contains carbon dioxide in solution. Statement-III : Rain water contains atmospheric oxygen. Which one of the following is correct in respect of the above statements ?

    • ABoth Statement-II and Statement-III are correct and both of them explain Statement-I
    • BBoth Statement-II and Statement-III are correct, but only one of them explains Statement-I
    • COnly one of the Statements II and III is correct and that explains Statement-I
    • DNeither Statement-II nor Statement-III is correct
    Show answer & solution

    Correct answer: (A) Both Statement-II and Statement-III are correct and both of them explain Statement-I

    All three statements are correct and both II and III explain I. Rainfall causes chemical weathering: rain water dissolves atmospheric CO2 to form weak carbonic acid, which chemically attacks rocks (carbonation), and it also carries dissolved atmospheric oxygen that drives oxidation of minerals like iron. Thus both the CO2 content (Statement-II) and the oxygen content (Statement-III) explain why rainfall weathers rocks, making option A correct.

  8. Q8medium

    Consider the following countries : (1) Finland (2) Germany (3) Norway (4) Russia. How many of the above countries have a border with the North Sea ?

    • AOnly one
    • BOnly two
    • COnly three
    • DAll four
    Show answer & solution

    Correct answer: (B) Only two

    Only two of the listed countries border the North Sea: Germany and Norway. Finland borders the Baltic Sea and Gulf of Bothnia, not the North Sea, and Russia's western coast is on the Baltic (and its north on the Arctic), not the North Sea. The North Sea is bordered by Britain, Norway, Denmark, Germany, the Netherlands, Belgium and France, so the count is two, giving option B.

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