Geography: UPSC Previous Year Questions (Prelims)

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.

Explanation

Option (a) is incorrect: Though it is accurate that the equator receives greater direct sunlight in comparison to the poles, the disparity in insolation is not as substantial as tenfold. The variance in insolation between the equator and poles predominantly arises from the curvature of the Earth and the inclination of its axis, causing sunlight to strike different latitudes at varying angles. Instead of a tenfold difference, the actual variation is estimated to be around 2.5 times.

Option (b) is incorrect: Insolation denotes the entirety of solar radiation reaching the Earth’s surface, encompassing a wide range of electromagnetic radiation. Although infrared radiation constitutes a substantial portion (about 49 %) of solar radiation, it does not represent two-thirds of the insolation. Insolation comprises visible light, ultraviolet (UV) radiation, and various other wavelengths along-side infrared radiation.

Option (c) is correct: The atmosphere warms up by absorbing longwave radiation emitted from the Earth’s surface, mainly in the form of infrared radiation. Water vapor is a strong absorber of infrared radiation. In the lower atmosphere, where its concentration is higher, it absorbs a significant portion of the Earth’s emitted infrared radiation.

Option (d) is incorrect: Infrared radiation is not part of the visible range, infrared radiation has wavelengths longer than those of visible light and is not perceptible to the human eye.

Explanation

Statement-I is incorrect: The tropical rainforest occurs near the equator and close to the tropics. Thus it receives heavy rainfall throughout the year. The heavy rain causes intense leaching of the soil which increases the acidity of the soil. Due to increased acidity, there is an issue of less nutrient absorption from the soil. Thus the claim that tropical rain forests are rich in nutrients is inappropriate.

Statement II is correct: As the tropical rainforest lies in a region of heavy rainfall and near to tropics, thus the climate here is hot and humid. This causes the rapid decomposition of the dead organic material present in the soil. Hence, Statement-I is incorrect, but Statement-II is correct.

Explanation

Statement-I is incorrect: The temperature contrast between continents and oceans is greater during winter than in summer. The reason for this is:

In summer, the land heats up faster than water due to its lower specific heat capacity. However, both the land and oceans are warm, so the temperature difference is relatively smaller. In winter, land cools down more rapidly than water because water has a higher specific heat capacity. This leads to a larger temperature contrast between the cooler land and relatively warmer oceans. Statement-II is correct: Specific heat is the amount of heat energy it takes to raise or lower the temperature of 1 gram of a substance by 1°Celsius. The specific heat of water is greater than that of dry soil, thus, water absorbs and releases heat more slowly than land.

Explanation

Statement 1 is correct: There are two types of body waves-P and S waves. The P-waves and S-waves are also known as primary waves and secondary waves, respectively. The P-waves move faster and are the first to arrive at the surface. Therefore, in a seismograph, P waves are recorded earlier than S waves. The S-waves arrive at the surface with some time lag.

Statement 2 is correct: In P-waves, the media particle vibrates parallel to the direction of the wave. Thus it causes the to-and-fro motion. Further, in the S-waves media particles vibrate perpendicular (up and down at right angles) to the direction of wave propagation i.e. in the right angle. P-waves S-waves Arrival Times Surface Waves Amplitude

Explanation

Thermal power is the largest source of electricity in India, accounting for around 70% of the country’s total power generation. It primarily relies on coal, gas, and oil as fuel sources, with coal-based plants being the dominant contributors.

Statement 1 is incorrect: Water is essential in thermal power plants for cooling high temperatures and generating steam to power turbines. In India, river water is primarily used for this purpose, but some plants, like Mundra Thermal Power Station in Gujarat, use seawater.

Statement 2 is incorrect: More than a third of India’s freshwater-based plants are in areas with high or extreme water stress. On average, they run at 15-25 % lower capacity than those in less water-stressed regions because of limited water availability. Ex-Suratgarh Thermal Power Plant (Rajasthan)

Statement 3 is incorrect: Many coal-based power plants in In-dia are privately owned and operated. For example, the Mundra Thermal Power Plant in Gujarat is owned by Adani Power and is one of the largest private-sector coal-based power plants in the country.

Explanation

Statement I is correct: Switzerland consistently ranks as the world’s leading gold exporter by value. In 2023, the country exported gold worth over $107 billion which makes it the top exporter globally. The country is home to some of the world’s largest and most advanced gold refineries, processing a significant portion of the global gold supply. This infrastructure enables Switzerland to import large quantities of raw gold, refine it, and then export high-quality gold products worldwide.

Statement II is incorrect: Switzerland does not hold the second-largest gold reserves globally. As of the latest data, the top countries by gold reserves are: United States>Germany>Italy>France>Russia>China> Switzerland.