Geography: UPSC Previous Year Questions (Prelims)

Explanation

United Kingdom: The UK (including its overseas territories) has a substantial number of time zones. Sources indicate the UK has 9 time zones, ranging from UTC-8 (Pitcairn Islands) to UTC+6 (British Indian Ocean Territory), plus its own GMT/BST. Denmark: Denmark, primarily due to Greenland and the Faroe Islands, has multiple time zones. Sources indicate Denmark (including its constituent countries) has 5 time zones, ranging from UTC-4 (parts of Greenland) to UTC+1 (mainland Denmark). New Zealand: New Zealand’s main islands use one time zone (NZST/NZDT), but its associated states and dependencies spread across different longitudes. Sources indicate New Zealand (including its territories like the Cook Islands, Niue, Tokelau, and Chatham Islands) has 5 time zones, ranging from UTC-11 (Niue) to UTC+13 (Tokelau, main islands with DST). Australia: Australia, a large continent, has several time zones on its mainland an d additional ones for its external territories. Sources indicate Australia (including its mainland and external territories like Heard and McDonald Islands, Cocos (Keeling) Islands, Christmas Island, Norfolk Island, Lord Howe Island) has 9 time zones, ranging from UTC+5 to UTC+11 or UTC+12 with DST. Brazil: Brazil is a large country but has fewer time zones than the others on this list with significant overseas territories. Brazil has 4 time zones, ranging from UTC-5 (Acre Time) to UTC-2 (Fernando de Noronha Time). This is not more than four.

Explanation

Statement 1 is correct: Anadyr in Siberia (Russia) and Nome in Alaska are geographically close, separated by the Bering Strait and the International Date Line (IDL). Because of the IDL, even though the two cities are near each other, they fall on different calendar days. So, when people are waking up for breakfast in these cities, it would indeed be different days.

Statement 2 is incorrect: When it is Monday in Anadyr, it is actually Sunday in Nome, not Tuesday. Anadyr is ahead of Nome by about 21 hours due to its position relative to the International Date Line. So the claim that it would be Tuesday in Nome when it’s Monday in Anadyr is wrong -- it’s still the previous day in Nome.

Explanation

Pair 1 is Correct: Botswana is one of the world’s largest producers of diamonds. The diamond industry is a major contributor to the country’s GDP and has played a central role in its economic growth since the 1970s.

Pair 2 is Correct: Chile is one of the top producers of lithium globally, particularly from its salt flats (like Salar de Atacama). It’s part of the famous "Lithium Triangle" along with Argentina and Bolivia.

Pair 3 is Correct: Indonesia is the world’s largest producer of nickel, a key metal for stainless steel production and increasingly important for electric vehicle battery manufacturing. The country has significant reserves and has implemented policies to control and benefit from its nickel resources.

Explanation

Pair I is Incorrect: Mallorca (also spelled Majorca) is the largest island in the Balearic Islands, which are an autonomous community of Spain located in the western Mediterranean Sea. Despite its Mediterranean location, it is not part of Italy.

Pair II is Incorrect: Normandy is a historic and cultural region in northern France, famous for the D-Day landings during World War II. It lies along the English Channel and has no association with Spain.

Pair III is Incorrect: Sardinia is the second-largest island in the Mediterranean Sea (after Sicily) and is an autonomous region of Italy. Though it is located relatively close to French territory (like Corsica), it is not part of France. v v v

Explanation

Fig.: Heat budget of the earth Statement-I is incorrect: The atmosphere is primarily heated by terrestrial radiation, which is the longwave radiation emitted by Earth’s surface after it absorbs solar radiation. While the atmosphere does absorb some direct solar radiation, it is the outgoing longwave radiation from the Earth’s surface (which gets trapped by greenhouse gases) that plays a major role in warming the atmosphere. From the diagram above, 65 units out of 100 units of heat are absorbed by the atmosphere in the form of longwave radiation. Thus terrestrial radiation is the major cause behind the heating of the atmosphere. Statement-II is correct: The longwave radiation is absorbed by atmospheric gases, particularly by carbon dioxide and other greenhouse gases. It is mainly because their molecular structure allows them to vibrate and absorb infrared energy emitted by the Earth’s surface.

Explanation

Statement 1 is correct: The troposphere is the low-ermost layer of the atmosphere. Its average height is 13 km and extends roughly to a height of 8 km near the poles and about 18 km at the equator.

Statement 2 is correct: At the equator, strong convectional currents form due to intense solar heating. These currents carry heat and moisture to great heights, pushing the troposphere upwards and increasing its thickness.

Statement 2 explains Statement 1: The greater thickness of the troposphere at the equator (Statement-I) is due to strong convectional currents (Statement-II). Intense solar heating at the equator causes air to rise, creating powerful convection currents that push the tropopause higher, expanding the troposphere. In contrast, weaker convection at the poles, due to minimal solar heating, results in a thinner troposphere.

Explanation

Isotherms are lines connecting places with equal temperatures. The horizontal distribution of temperature is depicted through isothermal maps, with the temperature reduced to sea level to eliminate altitude effects. Isotherms are generally parallel to the latitude. The deviation from this general trend is more pronounced in January than in July, especially in the northern hemisphere.

Statement 1 is correct: In January (winter in the Northern Hemisphere), continents lose heat quickly because land has a lower heat capacity than water. On the other hand, oceans retain heat longer due to their high heat capacity. As a result over continents (which are colder), isotherms shift southward, following the drop in temperature. While over oceans (which are warmer), isotherms shift northward, reflecting the retained warmth. This pattern is clearly visible on isothermal maps of the North Atlantic and Eurasian regions.

Statement 2 is incorrect: The Gulf Stream and the North Atlantic Drift are warm ocean currents, not cold. The Gulf Stream carries warm water from the Gulf of Mexico along the eastern coast of North America, while the North Atlantic Drift, an extension of the Gulf Stream, warms the western coasts of Europe. These warm currents increase temperatures in the North Atlantic region, making the area warmer, not colder. As a result, isotherms bend northward because the ocean is warmer than the surrounding continents, not due to cold currents. Fig.: Isotherms in January

Explanation

Statement I is correct: Rainfall plays a key role in weathering rocks through both physical and chemical processes. For instance rainfall water seeps into cracks, causing rocks to expand and contract. Over time, this weakens the rock structure. Similarly, In colder regions, rainwater freezes inside crevices and expands. This leads to cracks and eventually breaks the rock apart. Heavy rainfall also washes away loose particles, speeding up erosion. Chemically, rainwater reacts with minerals in the rock, causing slow decomposition and dissolution. Over time, these processes break down and lead to weathering of rocks.

Statement II is correct: Rainwater absorbs carbon dioxide (CO₂) from the atmosphere, forming a weak acid solution known as carbonic acid (H₂ CO₃). This acidic rainwater reacts with minerals in rocks, leading to chemical weathering, particularly in limestone and carbonate rocks, which dissolve in acidic conditions. This process is responsible for the formation of karst landscapes, caves, and sinkholes in limestone regions.

Statement III is correct: Rainwater absorbs oxygen (O₂) from the atmosphere, which plays a crucial role in oxidation reactions in rocks containing iron and other reactive minerals. Oxygen reacts with iron-rich minerals (e.g., magnetite, pyrite) in rocks to form iron oxides (rust), which weakens the rock structure. Both Statement-II (CO₂ in rainwater) and Statement-III (O₂ in rainwater) are correct. They both explain Statement-I, as they contribute to rock weathering through chemical processes like carbonation and oxidation.

Explanation

A volcano is an opening or rupture in the Earth’s crust through which molten rock (magma), gases, and ash escape from beneath the surface. When magma reaches the surface, it is called lava. Volcanic eruptions can shape mountains and islands, affecting both the environment and climate. Example:

Mount Etna(Italy), Kilauea (USA) The materials that reach the Earth’s surface in volcanoes include: lava flows pyroclastic debris volcanic bombs ash and dust gases such as nitrogen compounds sulphur compounds minor amounts of chlorine, hydrogen and argon etc.

Explanation

The Ganga River originates from the Gangotri Glacier in the Himalayas and flows into the Bay of Bengal. It drains about one-fourth of India’s land area and supports hundreds of millions of people. The river generally flows from northwest to southeast. The Yamuna River passes through the Delhi region and follows a southeastward path, roughly parallel to the Ganges. It eventually joins the Ganges near Prayagraj (Allahabad).

Option (b) is correct: The main left-bank tributaries of the Ganga are (from west to east)- in the order of joining:

1. Ramganga 2. Gomati

3. Ghaghara 4. Gandak

5. Kosi The major Right bank tributaries are Yamuna, Son, Punpun, Damodar, and Ajay. Among these, Yamuna is the largest and most significant.