UPSC 2024 Geography Questions with Answers

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 (CO) from the atmosphere, forming a weak acid solution known as carbonic acid (H CO). 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 (O) 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 (CO in rainwater) and Statement-III (O 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.

Explanation

The longest border between any two countries in the world is between Canada and the United States, which spans approximately 8,891 kilometers (5,525 miles). The border is divided into two: the border shared with Canada by the continental United States and the border that the state of Alaska shares with northern Canada. Eight Canadian provinces and thirteen American states run along the shared boundary.

Explanation

The Red Sea is a narrow body of water. It stretches about 1,200 miles (1,930 km) southeast from Suez, Egypt. The sea ends at the Bab el-Mandeb Strait, which connects to the Gulf of Aden. From there, it leads into the Arabian Sea.

Statement 1 is correct: The Red Sea is located in a region characterized by arid and semi-arid climates, with very little rainfall throughout the year. The surrounding regions, such as parts of Egypt, Saudi Arabia, and Sudan, experience low annual precipitation. The average annual rainfall along the Red Sea coast is less than 100 mm(annually) in most areas, with some regions experiencing no rainfall at all. For example, the city of Jeddah, Saudi Arabia, on the Red Sea coast, has an annual rainfall of only about 80 mm.

Statement 2 is correct: The Red Sea is almost unique in that it does not receive significant inflows from any large rivers. While there are some small streams and wadis (seasonal rivers such as Wadi Fatimah) that flow into the Red Sea, they do not significantly contribute to the volume of water in the sea. The Red Sea’s water balance is mainly influenced by evaporation, with a very high rate due to the hot and dry climate. However, according to Britannica, no water enters the Red Sea from rivers.

Explanation

Cote d’Ivoire (Ivory Coast) and Ghana are the two largest cocoa producers in the world, contributing over 60% of the global cocoa supply. Cote d’Ivoire alone produces about 40%, making it the top producer, while Ghana, the second-larg-est producer, is known for its high-quality cocoa beans. Cocoa from these countries is a key ingredient in the global chocolate industry, supplying major manufacturers like Nestlé, Mars, and Hershey. Their dominance in cocoa production is due to a tropical climate with hot, humid conditions, fertile soil ideal for cocoa cultivation, and a labor-intensive farming system supported by extensive smallholder networks.

Explanation

The North Sea is a shallow, northeastern arm of the Atlantic Ocean located between the British Isles and the mainland of northwestern Europe and covering an area of 220,000 square miles (570,000 square km).

Option (b) is correct:

The sea is bordered by:

The island of Great Britain to the southwest and west, The Orkney and Shetland islands to the northwest, Norway to the northeast, Denmark to the east, Germany and the Netherlands to the southeast Belgium and France to the south.