Geography: UPSC Previous Year Questions (Prelims)

Explanation

The Krishna-Godavari basin is a large sedimentary basin on the east coast of India, formed by the Krishna and Godavari rivers. It extends into the Bay of Bengal and is known for its significant hydrocarbon reserves, including both oil and natural gas. The Ravva offshore block, a prolific oil and gas producing area, is located within this basin. The basin’s geological history and structure have created favorable conditions for the accumulation of hydrocarbons, making it a crucial region for India’s energy sector.

Explanation

Maracaibo is a major city in northwestern Venezuela, situated on the western side of Lake Maracaibo, connected to the Gulf of Venezuela and the Caribbean Sea. Its strategic location and the discovery of vast oil reserves in the Maracaibo Basin have led to its development as a crucial port for the petroleum industry. Maracaibo serves as a primary hub for the export of crude oil and refined petroleum products, contributing significantly to Venezuela’s economy.

Explanation

Assertion (A) is true: Chile holds a prominent position in the global copper market, consistently ranking among the top producers worldwide. Its copper mining industry is a significant contributor to the nation’s economy and plays a crucial role in supplying copper to meet global demand. This sustained high level of production underscores Chile’s importance in the international copper trade. Reason (R) is true: Chile possesses exceptionally large deposits of porphyry copper, a type of ore deposit that is a primary source of copper globally. These deposits are characterized by their large size and relatively low-grade ore, but their sheer scale makes them economically viable for large-scale mining operations. The abundance of porphyry copper deposits in Chile is the fundamental reason for its substantial copper production and its leading role in the world market. The geological endowment of this resource directly explains Chile’s capacity to produce such significant quantities of copper. Thus, both A and R are true and R is the correct explanation of A.

Explanation

A is correctly matched with 4: Mount Rainier, a prominent stratovolcano in the Cascade Range, is located in the state of Washington within the United States. It is the high-est mountain in the state and a significant landmark in the Pacific Northwest. B is correctly matched with 1: Mount Etna, situated in Sicily, Italy, is one of the most active volcanoes in the world and the largest in Europe. C is correctly matched with 2: Paricutin, a cinder cone volcano located in the Mexican state of Michoacán, is notable for its relatively recent and well-documented formation. It emerged from a cornfield in 1943 and continued to erupt for nine years, eventually reaching a height of 424 meters. D is correctly matched with 3: Taal Volcano, a complex volcano located on the island of Luzon in the Philippines, is characterized by its unique setting within a lake-filled caldera. The volcano has a history of explosive eruptions, and it is considered one of the most active volcanoes in the Philippines.

Explanation

A is matched with 3: Cedar wood, known for its aromatic scent, durability, and reddish hue, is a valuable timber resource. While various species of cedar exist across the globe, Mexico is a notable source of cedar lumber, particularly from species found in its diverse forest ecosystems. B is matched with 2: Douglas Fir, a conifer native to western North America, is a commercially important timber species, particularly abundant in Canada. Known for its strength, straight grain, and relatively low cost, Douglas Fir is widely used in construction, including framing, flooring, and plywood production. C is matched with 4: Mahogany, a prized hardwood known for its rich reddish-brown color, fine grain, and durability, is a highly sought-after timber. Honduras, historically a major source of mahogany, has been associated with this valuable wood for centuries. Honduran mahogany has been used in fine furniture making, boatbuilding, and other high-end applications. D is matched with 1: Teak wood, renowned for its exceptional durability, water resistance, and golden-brown color, is a highly valued timber. Myanmar, formerly known as Burma, has long been a significant source of teak.

Explanation

Anthracite is a hard, brittle coal characterized by its high carbon content, typically ranging from 86% to 98%. It is considered the most metamorphosed type of coal, meaning it has undergone the most intense heat and pressure during its formation. This high carbon content makes anthracite the clean-est-burning type of coal, producing very little smoke or volatile matter. It is often referred to as "hard coal" and burns with a short, blue flame. Due to its cleaner-burning properties, anthracite is a preferred fuel source where minimizing air pollution is a priority. However, its relative scarcity and higher cost compared to other coal types limit its widespread use.

Explanation

Otto Schmidt, a Soviet geophysicist and astronomer, proposed a theory for the origin of the Earth and other planets in the solar system based on a cloud of gas and dust particles. His hypothesis, known as the "dust cloud hypothesis", suggested that the Sun, while already formed, captured or interacted with a surrounding cloud of interstellar material. This cloud, composed of gas, dust, and ice particles, began to rotate and flat-ten under the influence of the Sun’s gravity. Within this rotating disk, particles collided and clumped together, gradually forming larger and larger bodies. v v v

Explanation

A is correctly matched with 4: Pluto was considered the smallest planet in the solar system. It was reclassified as a dwarf planet in 2006 by the International Astronomical Union (IAU). Note: If we consider only the eight classical planets, Mercury is the smallest. B is correctly matched with 3: Jupiter is the largest planet in the solar system, with a diameter of about 139,820 km. It is a gas giant and has a mass more than twice that of all the other planets combined. It features the iconic Great Red Spot, a giant storm. C is correctly matched with 2: Venus located between Mercury and Earth is the second planet from the Sun. Venus is often called Earth’s "twin" due to its similar size and composition. D is correctly matched with 1: Mercury is the closest planet to the Sun, orbiting at an average distance of 57.91 million km (0.39 AU). It has the shortest orbit of all planets, completing one revolution around the Sun in 88 Earth days.

Explanation

Statement 1 is correct: Asteroids orbit the Sun in an elliptical path, similar to planets. They are rocky remnants from the early formation of the Solar System about 4.6 billion years ago. Their composition includes metals, silicates, and carbon-rich materials.

Statement 2 is correct: Most asteroids are much smaller, typically less than 1 km in diameter. There are millions of asteroids in the Solar System, ranging in size from tiny pebbles to massive bodies.

Statement 3 is incorrect: Most asteroids are located between the orbits of Mars and Jupiter, not Jupiter and Saturn. This region is called the Main Asteroid Belt, which contains the majority of known asteroids. Some asteroids such as Trojan asteroids, share orbits with Jupiter but are not found in the region between Jupiter and Saturn.

Explanation

Option (c) is correct: The correct sequence of the different layers of the atmosphere from the surface of the Earth upwards is: Troposphere Stratosphere Mesosphere Ionosphere Troposphere: This is the lowest layer of the atmosphere, extending from the Earth’s surface up to about 8-15 km. It contains most of the Earth’s weather systems and clouds. Stratosphere: Above the troposphere, this layer extends from around 15 km to 50 km. It contains the ozone layer, which absorbs and scatters ultraviolet solar radiation. Mesosphere: Above the stratosphere, the mesosphere stretches from 50 km to 85 km. It is the layer where meteors burn up upon entry into the Earth’s atmosphere. Ionosphere: This is not a distinct layer like the others but rather a region of the atmosphere (spanning from about 60 km to 1,000 km) where ionization of gases occurs. The ionosphere overlaps with the thermosphere and exosphere.