UPSC Static Quiz – Geography : 18 June 2026

Solution: A

• During the early developmental phase of the Solar System, the planets formed through the accretion of gas and dust around the young proto-Sun. The primordial atmospheres of the terrestrial planets, including Earth, were dominated by lighter gases like hydrogen and helium.
• However, the young Sun was highly active and emitted intense solar winds—streams of charged particles flowing outward into space. These high-energy solar winds stripped the light gases from the relatively weak gravitational grasp of the inner terrestrial planets. This process left them temporarily bare until volcanic degassing and later volatile accretion from comets created a denser, carbon-dioxide and water-vapour rich secondary atmosphere.
• Thus, Statement-I describes a correct geomorphological and astronomical fact, and Statement-II provides the correct physical mechanism for this loss.

Solution: C

• Statement 1 is correct: The Phanerozoic Eon is the current geological eon characterized by abundant, complex animal and plant life. It is divided into three major eras: the Paleozoic, the Mesozoic (the age of reptiles), and the Cenozoic (the age of mammals).
• Statement 2 is incorrect: The Great Oxidation Event did not occur during the Archean Eon. It occurred during the Paleoproterozoic Era of the Proterozoic Eon (around 2.4 to 2.0 billion years ago) when cyanobacterial photosynthesis produced enough oxygen to accumulate in the atmosphere and form the protective ozone layer.
• Statement 3 is correct: The Holocene Epoch is the latest subdivision of the Quaternary Period. It represents the warm interglacial stage that followed the retreat of the Pleistocene ice sheets, accommodating the rise of human civilization.

Thus, statements 1 and 3 are correct, which includes statement 3.

Solution: B

The equator is the primary parallel of latitude dividing the Earth into the Northern and Southern Hemispheres. It crosses several key water bodies across South America, Africa, and Asia. Among these, it passes directly through the Gulf of Guinea (Atlantic Ocean), Lake Victoria in East Africa, and the Pacific Ocean. However, the equator does not pass through Lake Tanganyika (which lies further south in the East African Rift), Lake Tonlé Sap in Cambodia, or Patos Lagoon in southern Brazil.

Solution: D

• Wet paddy (rice) cultivation requires hot, humid conditions, significant rainfall (over 100 cm), and flat, low-lying fields that can be flooded. In many parts of monsoon Asia, such as the interior parts of the Indo-Gangetic plain, Deccan Plateau, and northern China, either the rainfall is lower, the soil is different, or the terrain is not suitable for flooding.
• In these areas, farmers still practice intensive subsistence agriculture (high labour input on small plots) but cultivate other crops.
  • Wheat (4) is the dominant crop in the drier parts of the Indo-Gangetic plains (e.g., Punjab, Haryana, Western UP) and North China Plain.
  • Soya bean (1) and Sorghum (2) (Jowar) are important crops in the drier parts of China and India (e.g., Deccan plateau). They are more drought-resistant than rice.
  • Sugarcane (3) is also grown intensively in these regions, for example, in Uttar Pradesh in India, where it is a major cash crop within the subsistence framework.

All four crops are characteristic of the “other than paddy” variant of intensive subsistence agriculture, grown where conditions are not ideal for rice.

Solution: C

• Statement 1 is correct. The Red Sea is a long, narrow body of water situated in a hot, arid region. It experiences extremely high rates of evaporation. Furthermore, it receives almost no significant freshwater input from precipitation or rivers. Its only connection to the open ocean is through the narrow Strait of Bab-el-Mandeb. This combination of factors leads to exceptionally high surface salinity, often reaching 41 ppt.
• Statement 2 is correct. The Baltic Sea, located in Northern Europe, is a classic example of a brackish water body. It is semi-enclosed with only a narrow and shallow connection to the North Sea (and thus the Atlantic). It is surrounded by a large land area from which numerous rivers (e.g., Oder, Vistula) discharge vast amounts of freshwater. Evaporation rates are low due to the high latitude. This massive freshwater input and limited mixing with saltier ocean water result in very low surface salinity, typically ranging from 3 to 8 ppt.
• Statement 3 is correct. The Black Sea is another semi-enclosed sea with a large drainage basin, receiving freshwater from major rivers like the Danube, Dnieper, and Don. This creates a low-salinity surface layer (around 18 ppt). However, it has a restricted connection to the much saltier Mediterranean Sea through the Bosporus Strait. The dense, saline Mediterranean water flows into the Black Sea and sinks to the bottom. This creates a strong, stable stratification with a permanent halocline (a layer of rapid salinity increase) that prevents vertical mixing. As a result, the deep waters of the Black Sea are anoxic (lacking oxygen).