UPSC Prelims 2024 Analysis

Explanation

• Dhuandhar: This waterfall is located on the Narmada River, but the region is not Malwa. It is in Madhya Pradesh Mahakoshal region. Hence, pair 1 is incorrectly matched.

• Hundru: This waterfall is indeed located on the Subarnarekha River within the Chota Nagpur Plateau. Hence, pair 2 is correctly matched.

• Gersoppa (also known as Jog Falls): This waterfall is on the Sharavati River in the Western Ghats, not the Netravati River. Hence, pair 3 is incorrectly matched.

Explanation

Explanation: 

On June 21st, the Summer Solstice, the Earth's tilt positions the North Pole at its maximum inclination towards the Sun. Let's analyze each option:

• Equator: The equator receives 12 hours of daylight throughout the year, regardless of the season.

• Tropic of Cancer: On June 21st, the Sun is directly overhead at the Tropic of Cancer. Locations at and north of this latitude experience their longest day of the year, with more than 12 hours of daylight.

• Tropic of Capricorn: This latitude is in the Southern Hemisphere, experiencing its shortest day of the year on June 21st with less than 12 hours of daylight.

• Arctic Circle: On June 21st, the Arctic Circle experiences 24 hours of daylight. 

Therefore, both the Tropic of Cancer and the Arctic Circle experience more than 12 hours of daylight on June 21st.

Explanation

Explanation: 

Understanding Isotherms and Their Behavior

• Isotherms are lines on a map connecting points with the same temperature. 

• January is a winter month in the Northern Hemisphere.

• Land and Water Heating Differences: Land heats up and cools down faster than water. This leads to significant temperature differences between continents and oceans in winter.

Statement 1: Correct

• In January, continents are colder than oceans in the Northern Hemisphere. 

• Isotherms bend northward over oceans, indicating warmer temperatures. 

• Isotherms bend southward over continents, indicating colder temperatures.

Statement 2: Incorrect

• The Gulf Stream and North Atlantic Drift are warm ocean currents, not cold. 

• These currents bring warm water from the tropics towards Europe, making the North Atlantic relatively warmer in winter. 

• Isotherms bend northward over the North Atlantic due to these warm currents.

Conclusion: Only statement 1 is a correct inference from isothermal maps in January.

Explanation

• Italy and Japan are often cited as prime examples of countries with rapidly ageing populations and very low birth rates. Both countries have been grappling with the economic and social consequences of these demographic trends for several years.

• South Korea has also emerged as a country with significant demographic concerns. Its fertility rate is one of the lowest in the world, and its population is projected to start declining in the coming years.

• Nigeria and South Africa, while facing their own set of demographic challenges, are generally not highlighted for low birth rates or declining populations. Nigeria has a very young and rapidly growing population. South Africa’s population growth has slowed in recent years, but it is not yet experiencing a decline.

Explanation

Explanation: 

• Statement 1: Correct - Water vapour is indeed a gas, and its concentration generally decreases with altitude. This is because the air gets colder as we go higher, and colder air has a lower capacity to hold moisture.

• Statement 2: Incorrect - The percentage of water vapour in the atmosphere is highest near the equator and decreases as we move towards the poles. This is because the tropics receive the maximum solar radiation, leading to higher temperatures and more evaporation, which in turn increases the amount of water vapour in the air.

Explanation

The Ivory Coast and Ghana are by far the two largest producers of cocoa, accounting for more than 50 per cent of the world's cocoa.

West Africa is home to the largest cocoa producing countries worldwide, with 3.9 million tonnes of production in 2022.

In fact, there are about one million farmers in Côte d’Ivoire supplying cocoa to key customers such as Nestlé, Mars, and Hershey.

However, the massive influence of this industry has led to significant forest loss to plant cocoa trees.

Explanation

1. Brazil - Indri: Indris are lemurs found only in Madagascar, not Brazil. So, this pair is incorrect.

2. Indonesia - Elk: Elks are found in North America, Europe, and Asia, but not in Indonesia. This pair is incorrect.

3. Madagascar - Bonobo: Bonobos are found in the Democratic Republic of Congo, not Madagascar. This pair is also incorrect.

Therefore, none of the pairs are correctly matched.

Explanation

The border between Canada and the United States is the longest international border in the world, stretching approximately 8,891 kilometers (5,525 miles), including the border shared with Alaska. It is a peaceful boundary and includes both land and water segments.

Chile and Argentina:

• Length: Approx. 5,308 kilometres

• This is the third-longest international border in the world and the longest in South America.

• It follows the Andes mountain range for most of its length, with several high-altitude border crossings.

China and India:

• Length: Approx. 3,488 kilometers

• This border is the longest for India and spans regions like Ladakh, Himachal Pradesh, Uttarakhand, Sikkim, and Arunachal Pradesh.

• It is highly disputed in areas such as Aksai Chin and Arunachal Pradesh, leading to occasional tensions between the two nations.

Kazakhstan and Russian Federation:

• Length: Approx. 7,644 kilometers

• This is the second-longest international border in the world.

• It is largely flat, passing through vast steppes, and is a vital region for trade and natural resources between the two countries.

Explanation

• Finland: Finland borders the Baltic Sea, not the North Sea.

• Germany: Germany shares a border with the North Sea.

• Norway: Norway has a long coastline along the North Sea.

• Russia: Russia does not border the North Sea.

• In total 7 countries border the North Sea - United Kingdom, Norway, Denmark, Germany, The Netherlands, Belgium, France.

Therefore, only Germany and Norway border the North Sea.

Explanation

• Statement I: This statement is correct. The Sumed Pipeline is indeed a significant route for transporting oil and natural gas from the Persian Gulf to Europe. It bypasses the Suez Canal, offering an alternative path for these resources.

• Statement II: This statement is also correct. The Sumed Pipeline physically connects the Red Sea (where oil and gas are loaded onto ships from the Persian Gulf) with the Mediterranean Sea, providing a direct route for them to reach European ports.

• The connection between the Red Sea and the Mediterranean Sea established by the Sumed Pipeline directly explains its strategic importance for transporting oil and gas to Europe.  Statement II provides the geographical context for how Statement I functions.

Explanation

Explanation: 

• Donyi Polo Airport (Itanagar, Arunachal Pradesh): This newly constructed airport was inaugurated in 2022. It was built on undeveloped land, making it a greenfield project.

• Kushinagar International Airport (Uttar Pradesh): This airport was inaugurated in 2021. It was also built as a new entity on undeveloped land, qualifying as a greenfield project.

• Vijayawada International Airport (Andhra Pradesh): This airport has existed for several decades. While it has undergone significant expansion and modernization, it wasn't built from scratch on undeveloped land. Therefore, it's not a greenfield project.

Therefore, only Donyi Polo Airport and Kushinagar International Airport are greenfield projects.

Explanation

Coriolis Force: The Coriolis force is an inertial force that acts on objects in motion within a rotating frame of reference. On Earth, this force causes moving objects (like air masses or ocean currents) to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

• Statement 1 is correct: It increases with an increase in wind velocity - The magnitude of the Coriolis force is directly proportional to the speed of the moving object. Faster winds experience a stronger Coriolis deflection.

• Statement 2 is correct: It is maximum at the poles and is absent at the equator. - The Coriolis force is strongest at the poles because the Earth's rotation is fastest at these points. At the equator, the Earth's surface moves parallel to the axis of rotation, resulting in zero Coriolis effect.

Therefore, both statements 1 and 2 are correct.

Explanation

Explanation: 

• Statement-I: Correct - The troposphere is thicker at the equator than at the poles. This is because the equator receives more direct sunlight, leading to warmer temperatures and greater air expansion. This expanded air results in a greater height of the troposphere.

• Statement-II: Correct - Convection is a significant mode of heat transfer in the atmosphere. At the equator, intense solar heating causes air to rise rapidly in strong convectional currents. This rising air carries heat to higher altitudes, contributing to the vertical distribution of heat in the troposphere.

Statement II directly explains Statement I. The strong convectional currents mentioned in Statement II are the primary reason for the greater thickness of the troposphere at the equator, as explained in Statement I. The rising air due to convection leads to the expansion and increased height of the troposphere in equatorial regions.

Explanation

Explanation:

• Statement 1: The Red Sea is located in a desert region with very high temperatures and low humidity. This leads to very little rainfall or any form of precipitation.

• Statement 2: Due to its location, no major rivers are flowing into the Red Sea. The water in the Red Sea comes primarily from the inflow of saltier water from the Gulf of Aden through the Bab el-Mandeb Strait.

Hence, both statements (1 and 2) are correct.

Explanation

Explanation: 

• Gomati: The Gomti River originates in the Central Himalayas and joins the Ganga near Varanasi, Uttar Pradesh.

• Ghaghara: The Ghaghara River, also known as the Ghagra-Rapti River, is the largest tributary of the Ganga. It originates in the Nepal Himalayas and joins the Ganga near Chhapra, Bihar.

• Gandak: The Gandak River originates in the Nepal Himalayas and joins the Ganga near Patna, Bihar.

• Kosi: The Kosi River, also known as the Koshi River, is known for its erratic behaviour and floods. It originates in the Nepal Himalayas and joins the Ganga near Katihar, Bihar.

Therefore, the correct sequence is Gomati - Ghaghara - Gandak - Kosi.

Explanation

Explanation:

• Central Asia - Vosges - Fold Mountain: This is incorrect. The Vosges Mountains are located in Europe, not Central Asia. They are indeed folded mountains.

• Europe - Alps - Block Mountain: This is incorrect. The Alps, located in Europe, are a classic example of fold mountains, formed due to the collision of the African and Eurasian tectonic plates.

• North America - Appalachians - Fold Mountain: This is correct. The Appalachian Mountains in North America are old fold mountains.

• South America - Andes - Fold Mountain: This is correct. The Andes, running along the western edge of South America, are the longest continental mountain range in the world and are fold mountains formed due to the convergence of the Nazca and South American plates.

Therefore, only two rows have the information correctly matched.

Explanation

• Cashew: Originally native to Brazil, cashew was brought to India by Portuguese traders in the 16th century. 

• Papaya: Papaya also originated in the Americas, specifically in southern Mexico and Central America. 

• Red Sanders: This tree, known for its valuable reddish wood, is endemic to India. It is found in the Eastern Ghats, particularly in Andhra Pradesh.

Therefore, only Red Sanders is native to India.

Explanation

Pyroclastic debris: This is a general term for fragmental material ejected from a volcano during an eruption. It includes ash, pumice, cinders, and volcanic bombs.

Ash and dust: These are fine-grained particles of volcanic rock and glass that can be carried long distances by wind.

Nitrogen compounds: Nitrogen is a common gas released by volcanoes, and it can react with other elements in the atmosphere to form compounds such as ammonia and nitrogen oxides.

Sulphur compounds: Sulphur dioxide (SO2) is one of the main gases released by volcanoes. It can irritate the respiratory system and contribute to acid rain. Other sulphur compounds, such as hydrogen sulphide (H2S), can also be released in smaller amounts.

All of the above (1, 2, 3, and 4) are products of volcanic eruptions.

Explanation

The climate described by these characteristics is most likely a Marine West Coast Climate (Cfb) according to the Köppen climate classification system.

• Annual and daily range of temperatures is low: Marine west coast climates are known for their mild temperatures year-round. The influence of the nearby ocean moderates both summer highs and winter lows, resulting in a smaller range of temperatures compared to continental climates at similar latitudes.

• Precipitation occurs throughout the year: These regions experience frequent precipitation due to prevailing westerly winds carrying moist air from the ocean. The cyclones associated with these winds bring rain or snowfall throughout the year.

• Precipitation varies between 50 cm and 250 cm: The amount of precipitation in marine west coast climates can vary depending on factors like latitude, topography, and proximity to the ocean. The range of 50 cm to 250 cm falls within the typical range observed in these regions.

Explanation

Explanation: 

• Statement I: This statement is true. Rainfall is one of the reasons for the weathering of rocks.  Rainwater can cause both physical and chemical weathering. Physical weathering occurs due to the impact of raindrops, especially during heavy downpours. Chemical weathering happens when rainwater reacts with minerals in rocks, leading to their breakdown.

• Statement-II: This statement is true. Rainwater contains carbon dioxide in solution. Rainwater absorbs carbon dioxide from the atmosphere, forming weak carbonic acid (H2CO3). This slightly acidic nature of rainwater contributes to chemical weathering.

• Statement-III: This statement is true. Rainwater contains atmospheric oxygen. Rainwater dissolves atmospheric gases, including oxygen. The dissolved oxygen in rainwater plays a role in the oxidation of certain minerals in rocks, which is a form of chemical weathering.

Therefore, both Statement II and Statement III are correct, and both explain Statement I. Rainwater's acidity (due to dissolved carbon dioxide) and dissolved oxygen content contribute to the chemical weathering of rocks.