UPSC Static Quiz – Geography : 17 April 2026

Solution: C

• Statement I is correct because El Niño and La Niña represent opposite phases of the coupled ocean–atmosphere system known as the El Niño–Southern Oscillation. ENSO operates through periodic fluctuations in sea surface temperatures and atmospheric pressure across the equatorial Pacific, leading to distinct climatic impacts globally.
• Statement II is also correct and directly explains Statement I. El Niño is marked by anomalous warming of sea surface temperatures in the central and eastern equatorial Pacific Ocean, which weakens the trade winds and shifts convection eastward. In contrast, La Niña involves anomalous cooling in the same region, strengthening trade winds and enhancing convection over the western Pacific. These opposite temperature anomalies and atmospheric responses are what define them as opposing phases of the same climate system.
• Statement III is incorrect. While both phenomena do influence the Indian monsoon, El Niño is generally associated with weaker or deficient monsoon rainfall over India due to reduced convection and subsidence over the Indian region. La Niña, on the other hand, tends to enhance monsoon rainfall by strengthening atmospheric circulation favorable for precipitation.

Solution: D

• Point 1 is the “Jig-Saw-Fit” evidence, where the Atlantic coastlines of Africa and South America show a remarkable match.
• Point 2 is “Lithological Correlation”; ancient rock belts of 2,000 million years in Brazil align perfectly with those in West Africa, indicating they were once joined.
• Point 3 refers to “Paleoclimatic Evidence”; Tillite is a glacial sedimentary rock found in the Gondwana system across India, Africa, and Antarctica, suggesting these landmasses shared a common glacial history.
• Point 4 is the “Placer Deposit” evidence; rich gold deposits in Ghana are found in regions without source rocks, but they correspond to the gold-bearing veins in the Brazilian plateau, proving the continents were once contiguous. These multi-layered proofs shift the focus from simple observation to scientific synthesis.

Solution: C

• The S-wave shadow zone is larger than the P-wave shadow zone. S-waves (secondary waves) are transverse in nature and require a medium with shear strength to propagate. Since the Earth’s outer core is liquid, it cannot support shear stress, and thus S-waves are completely blocked beyond an angular distance of about 103° from the earthquake focus. This creates a wide shadow zone. In contrast, P-waves (primary waves), which are compressional, can travel through both solids and liquids. However, they undergo strong refraction at the core-mantle boundary, producing a smaller shadow zone between roughly 103° and 142°, after which they reappear.
• The second statement explains this phenomenon directly: S-waves cannot travel through liquids due to the absence of rigidity. The third statement refers to the discovery of the inner core by Inge Lehmann. By analyzing the refraction and reflection patterns of P-waves, she demonstrated that the inner core is solid, as P-wave velocities increase in this region. This provided crucial evidence for differentiating the liquid outer core from the solid inner core.

Solution: D

• The INSTC is a critical geoeconomic initiative involving India, Iran, and Russia.
• Statement 1 is correct; it utilizes ship, rail, and road to link Mumbai to Moscow.
• Statement 2 is correct; the infrastructure is divided into the Western route (via Azerbaijan), the Central route (across the Caspian Sea), and the Eastern route (via Kazakhstan/Turkmenistan).
• Statement 3 is correct; by avoiding the circuitous route through the Suez Canal, the INSTC is estimated to reduce transit time by 40% and costs by 30%. This project enhances maritime security by diversifying global supply chains away from single-point chokepoints.

Solution: A

• Statement I is correct. The concentration of dust particles (aerosols) is generally higher in subtropical and temperate regions, particularly in areas influenced by deserts (e.g., Sahara, Arabian, and Central Asian deserts). In contrast, equatorial regions experience high humidity and dense vegetation, which suppress dust suspension, while polar regions have limited sources of loose particulate matter.
• Statement II is also correct. Subtropical regions, especially around 20°–30° latitude, are dominated by high-pressure belts associated with descending air, leading to dry, arid conditions and sparse vegetation. These conditions promote the availability and uplift of dust particles by winds. Many temperate regions, particularly continental interiors, also experience seasonal dryness and wind activity that can mobilize dust.
• Statement II correctly explains Statement I. Dry winds and arid landscapes in these regions enhance the generation, transport, and persistence of dust particles in the atmosphere, resulting in higher dust concentrations compared to moist equatorial regions or ice-covered polar areas.