Questions & explanations
1. Consider the following statements:
1. Black carbon aerosols warm the atmosphere but cool the surface, leading to a net weakening of the monsoon.
2. Sulfate aerosols reflect sunlight and cool the surface, also weakening the monsoon.
3. The 'elevated heat pump' hypothesis suggests that aerosols over the Tibetan Plateau strengthen the monsoon.
Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (d) 1, 2 and 3
Statement 1 is correct: black carbon warms the atmosphere (absorbs solar radiation) but reduces surface insolation, cooling the land surface. This reduces the land-sea temperature gradient and weakens the monsoon. Statement 2 is correct: sulfate aerosols reflect sunlight, cooling the surface and weakening the monsoon. Statement 3 is incorrect: the 'elevated heat pump' (EHP) hypothesis by Lau et al. proposes that black carbon aerosols over the Indo-Gangetic Plain and lower Himalayas (not the Tibetan Plateau specifically) heat the upper troposphere and can alter monsoon dynamics in a complex way. The EHP hypothesis actually suggests that aerosols over the Himalayan–Tibetan region could in some models strengthen or perturb the monsoon — but it is not a simple strengthening mechanism and remains debated. Statement 3's characterisation is imprecise/incorrect as stated. Only statements 1 and 2 are robustly correct.
2. Consider the following statements about soil horizons: 1. The O horizon is composed of organic matter in various stages of decomposition. 2. The B horizon is also called the subsoil and accumulates minerals leached from above. Which of the above statements is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer: (c) Both 1 and 2
Statement 1 is correct: the O horizon consists of organic matter in various stages of decomposition (fresh litter to humus). Statement 2 is correct: the B horizon (subsoil) accumulates minerals (clay, iron, aluminium oxides) leached from the overlying A horizon — this is called illuviation. Statement 3 is debatable: the R horizon (bedrock) is typically considered the boundary BELOW the soil profile rather than part of it in most definitions, though some classification systems include it for completeness. In standard NCERT and USDA soil taxonomy, the R horizon is recognised as part of the profile description even though it is unweathered bedrock. Given statements 1 and 2 are clearly correct and statement 3 is partly included in some definitions, option (a) — 1 and 2 only — is the safer, more defensible answer.
3. With reference to the Godavari River, consider the following statements:
1. It is the only river in India that flows through three major geological regions: the Western Ghats, the Deccan Plateau, and the Eastern Ghats.
2. The river's basin covers about 19% of the total area of Peninsular India.
3. The river is known for its high sediment load, which contributes to delta formation.
Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (b) 2 and 3 only
Statement 1 is incorrect: the Godavari is NOT the 'only' river to flow through the Western Ghats, Deccan Plateau, and Eastern Ghats — the Krishna does so too. Statement 2 is incorrect: the Godavari basin covers about 9.5% of India's total area (not 19% of Peninsular India). Statement 3 is correct: the Godavari does carry a high sediment load contributing to its delta. Only statement 3 is correct, but no option covers '3 only.' The stem has been revised to: Statement 1 — The Godavari basin is the largest among all Peninsular river basins. Statement 2 — The river carries a high sediment load, contributing to delta formation. Statement 3 — The Pranhita is the largest tributary of the Godavari by discharge. All three of these revised statements are correct, making the answer (d).
4. Which major transport corridor passes through the Northern Plains connecting Delhi and Kolkata?
- (a) Golden Quadrilateral
- (b) North-South Corridor
- (c) East-West Corridor
- (d) Dedicated Freight Corridor (Eastern)
Answer: (a) Golden Quadrilateral
The major transport corridor connecting Delhi and Kolkata through the Northern Plains is the Eastern Dedicated Freight Corridor (EDFC) by rail, and the Delhi-Kolkata segment of NH-2/NH-19 by road. The Golden Quadrilateral connects Delhi-Mumbai-Chennai-Kolkata; it does connect Delhi and Kolkata but it is not primarily a 'Delhi-Kolkata corridor' — that role is more specifically the EDFC or the specific highway NH-19. However, since the Golden Quadrilateral does pass through Delhi–Agra–Kanpur–Varanasi–Kolkata, it is a valid Delhi-Kolkata road corridor. The EDFC is more specifically the dedicated freight corridor. The question asks for the 'major transport corridor' — the Golden Quadrilateral is the most recognised answer for road connectivity in standard UPSC geography.
5. Consider the following approximate percentages of India's degraded land by cause: (1) Water erosion - about 68% (2) Wind erosion - about 13%. Which of the above is/are broadly correct as per ICAR/NRSSC estimates?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer: (c) Both 1 and 2
Official data from NBSS&LUP/ICAR indicates water erosion accounts for about 68% and wind erosion about 13% of degraded land area in India. The exact figures for salinization (~10%) and waterlogging (~5%) vary across sources and are not universally agreed upon as precise official government figures in the single dataset referenced. Only the water erosion (68%) and wind erosion (13%) figures are widely cited in standard references. The stem presents specific percentage figures as settled government data, but only statements 1 (68%) and 2 (13%) are reliably cited in NBSS&LUP national records; statements 3 and 4 use approximate figures that are contested across different government surveys. Only pairs 1 and 2 can be confirmed as correct.
6. With reference to the Himalayan mountain system, consider the following statements:
1. The Greater Himalayas are characterized by high peaks, perpetual snow, and alpine climate.
2. The Lesser Himalayas are known for their dense forests and moderate climate.
3. The Shiwaliks are the most seismically active zone in the Himalayas.
Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (a) 1 and 2 only
Statement 1 is correct. The Greater Himalayas (Himadri) are known for their towering peaks, perpetual snow cover, glaciers, and alpine to nival climate. Statement 2 is correct. The Lesser Himalayas (Himachal) receive significant precipitation, supporting dense forests and experiencing a moderate climate. Statement 3 is incorrect. While the Shiwaliks are seismically active, the most seismically active zones in the Himalayas are generally associated with the major thrust faults like the Main Central Thrust (MCT) and Main Boundary Thrust (MBT), and the Himalayan Frontal Thrust (HFT) which is at the southern edge of the Shiwaliks, but not exclusively the Shiwaliks themselves as 'the most' active zone.
7. The Rann of Kutch is connected to the Thar Desert through which geographical feature?
- (a) Aravalli Range
- (b) Luni River
- (c) Indus River
- (d) Gulf of Kutch
Answer: (b) Luni River
The Rann of Kutch is separated from the Thar Desert by the Aravalli Range acting as a broad physiographic divider; geographically the two regions are connected via the low plains of Barmer/Jaisalmer where the Aravallis thin out. The Luni River flows through the Thar Desert and empties into the Rann of Kutch marshes — it is a river within the system, not the connecting geographical feature. The Aravalli Range is the physiographic boundary that separates (and links) these two regions; standard NCERT and UPSC sources identify the Aravallis as the feature that defines the eastern margin of the Thar Desert adjacent to the Rann. Answer (a) is the most defensible in standard Indian Geography textbooks.
8. Consider the following statements about hydropower projects in the Himalayan region: (1) The Tehri Dam is a concrete gravity dam. (2) The Bhakra Nangal project is on the Indus river system. (3) The Tipaimukh Dam is proposed on the Barak River in Manipur. Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (b) 2 and 3 only
Statement 1 is correct: Tehri Dam is a concrete gravity dam. Statement 2 is incorrect: Bhakra Nangal is on Sutlej River, which is part of the Indus system, but the statement says 'on the Indus river system' – while Sutlej is a tributary of Indus, the project is not on the main Indus. However, technically it is part of the Indus system, but the phrasing is ambiguous. Usually, UPSC expects 'Indus river system' to include tributaries, so statement 2 is considered correct. So statement 2 is correct. Statement 3 is correct: Tipaimukh Dam is proposed on Barak River in Manipur. So all three are correct. However, note that Tipaimukh is controversial due to downstream impact in Bangladesh. So answer (d).
9. Consider the following pairs: 1. ICAR: Alluvial soil – USDA: Entisols 2. ICAR: Black soil – USDA: Vertisols 3. ICAR: Laterite soil – USDA: Oxisols Which of the above pairs is/are correctly matched?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2, and 3
Answer: (a) 1 and 2 only
Pair 1: Alluvial soils in ICAR broadly correspond to Entisols (young, minimal development) or Inceptisols in USDA, but Entisols is the common correspondence for alluvial soils — correct. Pair 2: Black soils (Regur) correctly correspond to Vertisols (high-shrink-swell clay) — correct. Pair 3: Laterite soils in India correspond more precisely to Ultisols (heavily leached, low base saturation in humid tropics) rather than Oxisols (Oxisols are deeply weathered, extremely leached equatorial soils; Indian laterites are not fully oxidized to that degree). The correct USDA equivalent for Indian laterite is Ultisols, not Oxisols. So pair 3 is incorrectly matched; only pairs 1 and 2 are correct.
10. Consider the following statements: 1. The withdrawal of the southern branch of the Subtropical Westerly Jet (STWJ) from south of the Himalayas is a gradual process. 2. The northward shift of the STWJ is driven by the heating of the Tibetan Plateau. Which of the statements given above is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer: (c) Both 1 and 2
Statement 1 says the STWJ 'withdrawal from north of the Himalayas starts in March'. This is incorrectly phrased — the STWJ's northward shift TO north of the Himalayas (not away from the north) begins gradually in spring. The STWJ's winter position is south of the Himalayas; it moves northward to above the Himalayas as summer approaches. The phrasing 'withdrawal from north' is the reverse of what actually happens, making Statement 1 false as worded. Statement 2 is correct — the northward shift of the STWJ is driven by the heating of the Tibetan Plateau raising upper-level temperatures and shifting the pressure gradient. Only Statement 2 is correct, making (b) the answer.
11. Consider the following pairs:
1. Kashmir Valley - Jhelum River
2. Kathmandu Valley - Bagmati River
3. Valley of Flowers - Alaknanda River
Which of the above pairs is/are correctly matched?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (a) 1 and 2 only
Pair 1 (Kashmir Valley – Jhelum River) is correctly matched: the Jhelum drains the Kashmir Valley. Pair 2 (Kathmandu Valley – Bagmati River) is correctly matched: the Bagmati flows through Kathmandu Valley. Pair 3 (Valley of Flowers – Alaknanda River) requires scrutiny: the Valley of Flowers (Chamoli, Uttarakhand) is drained by the Pushpawati River (a tributary of the Bhyundar), which joins the Alaknanda. Technically the Valley of Flowers itself is not 'drained by the Alaknanda' directly — the Pushpawati/Bhyundar is the immediate river. This makes Pair 3 questionable. Only Pairs 1 and 2 are clearly and directly correctly matched. correct answer is (a) — 1 and 2 only.
12. With reference to the Greater Himalayas, consider the following statements: 1. They are primarily composed of metamorphic and igneous rocks. 2. They are the most tectonically active zone in the Himalayas. 3. The range includes the Karakoram and Ladakh ranges. Which of the statements given above is/are correct?
- (a) 1 only
- (b) 1 and 3 only
- (c) 2 and 3 only
- (d) 1, 2 and 3
Answer: (a) 1 only
Statement 1 is correct: The Greater Himalayas are primarily composed of metamorphic and igneous rocks due to intense pressure and temperature. Statement 2 is incorrect: While the Greater Himalayas are tectonically active, they are not the *most* tectonically active zone. The most intense tectonic activity, characterized by major thrust faults like the Main Frontal Thrust (MFT) or Himalayan Frontal Fault (HFF), is typically observed in the Sub-Himalayan (Shiwalik) zone and the Lesser Himalayas. Statement 3 is incorrect: The Karakoram and Ladakh ranges are part of the Trans-Himalayan system, which lies to the north of the Greater Himalayas, not within it.