Geography

Statement I: Correct Subtropical and temperate regions have more dust due to dry conditions, sparse vegetation, and strong winds.

Statement II: Incorrect Subtropical and temperate regions have more dry winds, not less, which help lift dust.

Correct Answer: Only Statement I is correct.

Statement I is correct: During the Northern Hemisphere winter (January), isotherms (lines of equal temperature) do not run parallel to latitudes. Instead, they deviate significantly: they bend toward the equator over land and toward the poles over water.

Statement II is correct: Land has a lower specific heat than water, meaning it loses heat much faster. Consequently, in January, the large landmasses of North America and Eurasia are significantly colder than the Atlantic and Pacific Oceans at the same latitude.

The Relationship: Statement II explains Statement I: Because the land is colder than the ocean, a line of constant temperature (isotherm) leaving the warm ocean must "dip" south toward the warmer tropical latitudes to find the same temperature once it hits the cold land. When that same line leaves the cold land and enters the warm ocean, it must "climb" north toward the colder polar latitudes to maintain that same temperature value. Thus, the temperature difference is the direct cause of the bending pattern.

Statement I: Correct Chalk is permeable (water passes easily); clay is impermeable (water passes poorly).

Statement II: Correct Chalk is porous, with many small holes that hold water, making it permeable.

Statement III: Incorrect Clay is porous but with very tiny pores that restrict water flow; it is impermeable but not non-porous.

Correct Answer: Only Statements I and II are correct; Statement II explains Statement I.

Anadyr (Russia) and Nome (Alaska, USA) lie close to each other geographically but are separated by the International Date Line, leading to a significant difference in calendar dates despite similar times of day.

Statement I: Correct Due to the International Date Line, Anadyr and Nome can have the same time of day but different dates.

Statement II: Incorrect When it's Monday in Anadyr, it is still Sunday in Nome, not Tuesday—Anadyr is ahead of Nome by almost 21 hours.

Statement I is correct: Satellite data (such as the GRACE mission) has confirmed that the Earth's rotational axis is drifting and the speed of rotation is slightly changing. Since the late 20th century, this "Polar Drift" has accelerated and shifted direction.

Statement II is correct: Solar flares and Coronal Mass Ejections (CMEs) release high-energy particles and radiation that impact the Earth's thermosphere and magnetosphere. While this causes geomagnetic storms and affects satellite drag, it has no significant impact on the orientation of the Earth's rotational axis.

Statement III is correct: When massive polar ice sheets melt, the resulting water is redistributed. Due to centrifugal force, this water accumulates more near the equator than at the poles. This represents a major surface mass redistribution.

The Relationship: Statement III explains Statement I. In physics, when the mass of a rotating sphere is moved from the axis (the poles) toward the perimeter (the equator), the "Moment of Inertia" increases, causing a shift in the axis of rotation and a slight slowing of the rotation speed.

Statement I is correct: Geological matching (Jigsaw Fit) shows that the 2,000-million-year-old belt of ancient rocks from the Brazilian coast matches those from Western Africa. This suggests the two continents were once joined.

Statement II is correct: This refers to "Placer Deposits." Ghana possesses rich placer deposits of gold despite having no known source rock (mother lode) in the region. The gold-bearing veins are actually located in Brazil, proving the continents were once side-by-side.

Statement III is correct: The Gondwana system of glacial tillite sediments found in India has identical counterparts in six different landmasses: Africa, the Falkland Islands, Madagascar, Antarctica, Australia, and South America. This provides powerful evidence of a shared climatic and geological history.

Correct Answer: All three statements are correct.

Statement I is correct: Without the atmosphere to trap heat, the Earth's surface temperature would drop to well below freezing, making it too cold to support life as we know it. In statement 1 though it's an extreme statement but from UPSC CSE point of view it's generally considered true.

Statement II is correct: The atmosphere absorbs and retains heat (a natural greenhouse effect), which helps maintain the Earth's average temperature within a habitable range.

Statement III is correct: Gases such as carbon dioxide, methane, and water vapor are particularly effective at absorbing and trapping infrared radiation, helping to warm the planet.

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.

* 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.

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.

* 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.

Statement 1 is Correct: The Coriolis force is directly proportional to the velocity of the moving object. Therefore, as wind velocity increases, the magnitude of the Coriolis force acting on it also increases, leading to a greater deflection.

Statement 2 is Correct: The Coriolis force is proportional to the sine of the latitude. At the equator (0° latitude), the sine of 0° is zero, so the Coriolis force is absent. At the poles (90° latitude), the sine of 90° is 1 (maximum), making the Coriolis force strongest at these points. It is important to note that while the linear velocity of Earth's rotation is highest at the equator and zero at the poles, the Coriolis effect depends on the rotation of the coordinate system itself, which is most pronounced at the poles.

* 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.

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.

Statement 1 (Equator) is incorrect: The Equator experiences exactly 12 hours of daylight throughout the year, as it lies midway between the poles and the sun's rays fall almost equally throughout the year.

Statement 2 (Tropic of Cancer) is correct: On June 21 (Summer Solstice), the Northern Hemisphere is tilted toward the Sun, and the Tropic of Cancer (23.5° N) receives the direct rays of the Sun. Hence, regions along this latitude experience more than 12 hours of daylight.

Statement 3 (Tropic of Capricorn) is incorrect: The Tropic of Capricorn (23.5° S) lies in the Southern Hemisphere, which is tilted away from the Sun on June 21. Therefore, it experiences less than 12 hours of daylight.

Statement 4 (Arctic Circle) is correct: On June 21, the Arctic Circle (66.5° N) experiences 24 hours of continuous daylight — known as the Midnight Sun phenomenon.

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


Statement 1 is correct: In a seismograph, P waves are recorded earlier than S waves. This is true because P waves, also known as Primary waves, are the first to be recorded by a seismograph during an earthquake. They are faster and hence, reach the recording instrument before the S waves.

Statement 2 is correct: P waves are longitudinal or compressional waves, which means the particles in these waves vibrate in the same direction as the wave propagation. On the other hand, S waves, or Secondary waves, are transverse waves, where the particle motion is perpendicular to the direction of wave propagation. Therefore, both statements are correct.


Statement-I is incorrect: The temperature contrast between land and ocean is actually greater in winter, not in summer. In winter, land loses heat quickly and becomes much colder, while the ocean retains heat and stays relatively warm → large contrast. In summer, both land and ocean warm up, but the difference is less pronounced compared to winter → smaller contrast.

Statement-II is correct: Water has a higher specific heat capacity than land. It heats up and cools down more slowly, which explains why oceans have a moderating influence on temperature.

* While it is true that the equator receives more direct sunlight compared to the poles, the actual difference in insolation is not as large as ten times. The difference in insolation between the equator and poles is primarily due to the curvature of the Earth and the tilt of its axis, resulting in varying angles at which sunlight reaches different latitudes.

* Insolation includes various wavelengths, such as visible light, ultraviolet rays, and infrared rays, but infrared rays do not constitute two-thirds of it.

* Water vapour is a greenhouse gas that absorbs infrared radiation emitted by the Earth's surface. This absorption contributes to the greenhouse effect and helps regulate the Earth's temperature. Hence, this is the correct statement.

* Infrared waves are not part of the visible spectrum; they have longer wavelengths than visible light.

Statement 1 is correct. The trade winds in the tropical zone blow from east to west, causing the western sections of the oceans to be warmer than the eastern sections. This is because these winds push the warm surface waters towards the west.

Statement 2 is correct. On the other hand, in the temperate zone, the westerlies blow from west to east. These winds push the warm waters towards the eastern sections of the oceans, making them warmer than the western sections.

Therefore, both statements are correct.


Dewdrops are formed when the temperature drops to the dew point and the air becomes saturated with water vapour.

On a clear night, the Earth's surface loses heat through radiation and can reach a temperature low enough to form dewdrops.

However, on a cloudy night, the clouds act like a blanket, reflecting back the Earth's radiation. This keeps the temperature of the air near the ground warmer, preventing it from reaching the dew point and thus, dewdrops are not formed.

Statement 1 is Correct: Coral reefs primarily thrive in warm, shallow, clear tropical waters between 30°N and 30°S latitudes, where sea surface temperatures typically remain between 20°C and 30°C.

Statement 2 is Correct: These three countries account for over 40% of the world's coral reef area, with Indonesia holding approximately 18%, Australia 17%, and the Philippines 9%.

Statement 3 is Correct: While rainforests have a higher number of species, coral reefs have greater phyletic diversity, hosting 32 of the 34 recognized animal phyla compared to only about 9 phyla found in tropical rainforests.

Statement 1 is correct. The Earth's magnetic field does reverse polarity every few hundred thousand years, on average.

Statement 2 is incorrect. The early Earth's atmosphere did not have significant oxygen and likely had a lot of carbon dioxide and other greenhouse gases.

Statement 3 is correct. The rise of photosynthetic organisms like cyanobacteria significantly increased the amount of oxygen in the atmosphere over time.

Therefore, the correct answer is (c) 1 and 3 only.

The eastward flow of the Equatorial Counter-Current (ECC) is primarily driven by the accumulation of water on the western sides of ocean basins.

1. The North and South Equatorial Currents are driven westward by the Trade Winds, causing water to 'pile up' against the western shores (e.g., the western Pacific or western Atlantic). 2. This accumulation creates a higher sea level in the west compared to the east, resulting in a pressure gradient. 3. In the zone between these two westward currents (the Doldrums), where surface winds are weak, this accumulated water flows back eastward under the influence of gravity to restore the ocean's equilibrium. 4. While the convergence of the two equatorial currents leads to this 'piling up' and subsequent downwelling (sinking of water), the resulting pressure gradient is what facilitates the eastward return flow known as the Equatorial Counter-Current.

Tropical cyclones require specific atmospheric and oceanic conditions to originate, including warm sea surface temperatures (above 26.5°C), the presence of the Coriolis force, and a pre-existing low-pressure disturbance.

1. Role of the ITCZ: The Inter-Tropical Convergence Zone (ITCZ) is a region where the trade winds of the Northern and Southern Hemispheres converge, creating the low-level atmospheric instability and rising moist air necessary for cyclone formation. In the South Atlantic and South Eastern Pacific, the ITCZ stays mostly north of the equator and seldom migrates into these regions, leaving them without the necessary 'trigger' for cyclones.

2. Vertical Wind Shear: These regions are also characterized by strong vertical wind shear (the change in wind speed and direction with height). High shear prevents the vertical development of thunderstorms and prevents them from organizing into a cyclonic structure.

3. Sea Surface Temperatures: While the explanation notes temperatures are generally warm enough, these specific regions are influenced by cold ocean currents (the Benguela Current in the South Atlantic and the Humboldt Current in the South Eastern Pacific), which keep the waters relatively cooler than other tropical basins, further inhibiting cyclone genesis.

Among the given options, the lack of the ITCZ is the primary reason why cyclones do not originate in these areas.

Statement 1 is Correct: The Sun's gravitational pull contributes to tide generation. Although the Sun is significantly more massive than the Moon, its immense distance from Earth results in a tidal-generating force that is approximately 46% as strong as the Moon's.

Statement 2 is Correct: The Moon's gravitational pull is the primary force responsible for tides. It exerts a stronger pull on the side of the Earth facing it, drawing ocean water toward it and creating a tidal bulge.

Statement 3 is Correct: Tides are also influenced by centrifugal force, which arises from the revolution of the Earth and Moon around their common center of mass (the barycenter). This force acts in the opposite direction to the Moon's gravitational pull; on the side of the Earth facing away from the Moon, the centrifugal force exceeds the Moon's weakened gravitational pull, creating a second tidal bulge.

According to the U.S. Geological Survey, over 68 percent of the freshwater on Earth is found in ice caps and glaciers, and just over 30 percent is found in groundwater.

Only about 0.3 percent of our freshwater is found in the surface water of lakes, rivers, and swamps.


The most important fishing grounds of the world are located where warm and cold oceanic currents meet. The convergence of these currents leads to the mixing of waters, which creates an ideal temperature and environment for the rapid growth of phytoplankton (microscopic plants). Since phytoplankton is the primary food source for fish, these regions support a massive and diverse marine population.

Key Examples: 1. The Grand Banks (Newfoundland): This is one of the world's richest fishing grounds, formed where the cold Labrador Current meets the warm Gulf Stream. 2. North West Pacific (Near Japan): A highly productive zone where the cold Oyashio Current meets the warm Kuroshio Current.

While regions with coastal upwelling (like the Humboldt Current) are also significant fishing grounds, the specific phenomenon of warm and cold current convergence is the primary reason for the productivity in the Grand Banks and the seas around Japan.