Practice 100+ free UPSC Physical Geography MCQs with answers and detailed explanations. Cover Earth Structure, Landforms, Earthquakes, Volcanoes, Climate, Atmosphere, Oceans and Biosphere for UPSC Prelims.
This quiz contains 115 carefully selected multiple-choice questions (MCQ) with detailed explanations for each answer. Questions cover important topics from Geography.
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100+ Free UPSC Physical Geography MCQs with Answers
Description
Practice 100+ free UPSC Physical Geography MCQs with answers and detailed explanations. Cover Earth Structure, Landforms, Earthquakes, Volcanoes, Climate, Atmosphere, Oceans and Biosphere for UPSC Prelims.
Difficulty
Hard
Num Questions
115
Points Per Question
1
Time Limit
100 minutes
All MCQ Questions with Answers and Explanations
Question 1: Which of the following statement(s) is/are correct? (1) The physical characteristics of a region may change over time. (2) Endogenic and exogenic processes operate completely independently of each other. (3) To understand present-day landforms, it is essential to study both their origin and evolution.
Correct Answer:
B
— Only 1 and 3 are correct.
Explanation:
The Earth is a dynamic planet; therefore, its physical characteristics change over time. Endogenic and exogenic processes interact with one another and do not operate independently. To understand any landform accurately, it is necessary to study both its origin and its subsequent evolution.
Question 2: Which of the following statements is the most appropriate regarding the methodology of studying Physical Geography?
Correct Answer:
A
— Physical Geography studies the Earth's processes not only individually but also in terms of their interrelationships.
Explanation:
Modern Physical Geography is an integrated science that studies the interrelationships among the lithosphere, atmosphere, hydrosphere, and biosphere. Hence, climate change, erosion, biodiversity, and ocean circulation are understood through an integrated approach.
Question 3: Which of the following statement(s) is/are correct? (1) The unidirectional flow of energy is a fundamental characteristic of an ecosystem. (2) Decomposers play an important role in the recycling of matter. (3) In the absence of decomposers, nutrient cycling would be severely disrupted.
Correct Answer:
C
— 1, 2 and 3 are all correct.
Explanation:
Energy flows through an ecosystem in one direction, whereas decomposers convert dead organic matter into simpler substances, ensuring the recycling of nutrients. In their absence, biogeochemical cycles would be severely disrupted.
Question 4: Which of the following is the most appropriate conclusion regarding ocean currents?
Correct Answer:
A
— Ocean currents can influence global climate, coastal environments, and marine biological productivity.
Explanation:
Ocean currents play a vital role in the global redistribution of heat and significantly influence coastal climate, marine biological productivity, and fishery resources. Their formation and movement are governed by multiple factors, including prevailing winds, the Coriolis effect, differences in water density arising from temperature and salinity, and the configuration of ocean basins. Therefore, the other options are either overly restrictive or overgeneralized.
Question 5: Which of the following statement(s) is/are correct? (1) One reason for the stability of the stratosphere is the presence of temperature inversion. (2) Compared to the troposphere, vertical convection is generally weaker in the stratosphere. (3) Therefore, most rainfall occurs in the stratosphere.
Correct Answer:
D
— Only 1 and 2 are correct.
Explanation:
In the stratosphere, temperature increases with altitude, limiting vertical convection and making the layer relatively stable. Most rainfall and other weather phenomena occur in the troposphere; therefore, the third statement is incorrect.
Question 6: With reference to the Indian Monsoon, choose the correct answer regarding the following statements. (1) Ocean-atmosphere phenomena such as El Niño can influence the Indian Monsoon. (2) If El Niño develops in a particular year, India must necessarily receive below-normal rainfall. (3) The behaviour of the Indian Monsoon is the result of the combined influence of several global and regional factors.
Correct Answer:
B
— Only 1 and 3 are correct.
Explanation:
El Niño can influence the Indian Monsoon, but its impact is not identical every year. The Indian Monsoon is also affected by Indian Ocean conditions, the Himalayas, jet streams, monsoon circulation, and other ocean-atmosphere processes. Therefore, the second statement is incorrect because of the word "necessarily."
Question 7: Which of the following statements is the most appropriate regarding volcanic activity?
Correct Answer:
C
— A volcano remaining quiet for a long period does not prove that it has become permanently extinct.
Explanation:
Dormant volcanoes may become active again even after remaining inactive for long periods. Therefore, a prolonged interval of inactivity alone is insufficient to classify a volcano as permanently extinct. The other options are either absolute or factually incorrect.
Question 8: Which of the following statement(s) is/are correct? (1) The carrying capacity and competence of a river are identical concepts. (2) Changes in the velocity of a river may affect both erosion and deposition. (3) Changes in the base level may alter the longitudinal profile of a river.
Correct Answer:
D
— Only 2 and 3 are correct.
Explanation:
Carrying capacity refers to the total quantity of sediment a river can transport in a given period, whereas competence refers to the maximum size of particles that the river can transport. Hence, the first statement is incorrect. Changes in river velocity influence both erosion and deposition, while changes in base level may lead to the readjustment of the river's longitudinal profile.
Question 9: In the context of the Plate Tectonics Theory, which of the following conclusions is the most appropriate?
Correct Answer:
A
— The theory provides a unified explanation for many major geomorphological phenomena occurring on the Earth's surface.
Explanation:
Plate Tectonics is the unifying theory of modern geology that explains continental drift, seafloor spreading, mountain building, volcanism, and most earthquakes. The other options unjustifiably restrict its explanatory scope.
Question 10: Which of the following statement(s) is/are correct? (1) Even in the absence of active tectonic activity, earthquakes are not entirely impossible in a region. (2) All intraplate earthquakes occur solely due to the reactivation of ancient faults. (3) The present seismic behaviour of a region may also be influenced by its geological history.
Correct Answer:
B
— Only 1 and 3 are correct.
Explanation:
Earthquakes may occur within tectonic plates; therefore, the first statement is correct. A region's geological history, ancient faults, stress redistribution, and other structural factors may influence present-day seismicity, making the third statement correct as well. However, it is incorrect to conclude that all intraplate earthquakes are caused solely by the reactivation of ancient faults.
Question 11: Which of the following statement(s) is/are correct? (1) Average rainfall alone is not sufficient to understand the climate of a region. (2) Temperature, wind, humidity and seasonal distribution are among the important determinants of climate. (3) If two regions have the same average annual rainfall, their climates will necessarily be the same.
Correct Answer:
D
— Only 1 and 2 are correct.
Explanation:
Climate is a multidimensional concept that includes temperature, rainfall, humidity, winds, seasonal distribution, and extreme events. Average rainfall alone cannot fully determine the climate of a region. Areas with similar annual rainfall may differ significantly in their thermal and seasonal characteristics.
Question 12: Which of the following statement(s) is/are correct? (1) Matter is recycled within the biosphere. (2) Energy flows in a unidirectional manner. (3) In the absence of producers, the long-term existence of most ecosystems would be at risk.
Correct Answer:
C
— 1, 2 and 3 are all correct.
Explanation:
Matter such as carbon, nitrogen, and water is recycled through various biogeochemical cycles in the biosphere, whereas energy flows unidirectionally from producers to consumers. Producers constitute the primary energy base of most ecosystems; without them, long-term ecosystem stability would not be possible.
Question 13: Which of the following conclusions is not appropriate based on the vertical structure of the atmosphere?
Correct Answer:
D
— Temperature necessarily decreases with increasing altitude in every atmospheric layer.
Explanation:
The pattern of temperature variation differs across atmospheric layers. Temperature decreases in the troposphere, increases in the stratosphere, decreases again in the mesosphere, and increases in the thermosphere. Therefore, the conclusion that temperature "necessarily decreases" with altitude is incorrect.
Question 14: Which of the following statement(s) is/are correct? (1) All earthquakes are caused by the movement of tectonic plates. (2) Earthquakes may also be generated by volcanic activities. (3) Human-induced processes such as large reservoirs, deep mining activities, and deep injection of waste fluids may trigger seismic events under limited conditions.
Correct Answer:
C
— Only 2 and 3 are correct.
Explanation:
Most earthquakes are caused by tectonic plate movements, but not all. Volcanic activities and human-induced processes such as large reservoirs, deep mining, and deep injection of waste fluids can also induce seismicity. Therefore, the first statement is incorrect because of the word "all."
Question 15: Which of the following statement(s) is/are correct? (1) Both erosion and deposition may occur simultaneously in the middle course of a river. (2) Meanders are formed only by deposition. (3) A change in the base level of a river may influence its erosional capacity.
Correct Answer:
B
— Only 1 and 3 are correct.
Explanation:
In the middle course of a river, erosion occurs along the outer bank while deposition takes place along the inner bank simultaneously. Meanders are not formed solely by deposition but develop through the combined action of erosion and deposition. Changes in the base level influence the river's energy and erosional capacity.
Question 16: Which of the following cannot necessarily be inferred from the Plate Tectonics Theory?
Correct Answer:
D
— All mountains have been formed solely due to the convergence of tectonic plates.
Explanation:
The Plate Tectonics Theory explains the creation and destruction of oceanic crust, continental drift, most earthquakes, and many mountain systems. However, not all mountains are formed solely through plate convergence. Some mountains develop due to volcanic activity, faulting, doming, or other geological processes. Therefore, option (D) is not a necessary conclusion of the Plate Tectonics Theory.
Question 17: Which of the following statement(s) is/are correct? (1) Most of our knowledge about the Earth's internal structure is based on indirect evidence rather than direct observation. (2) Changes in the velocity of seismic waves indicate only changes in the chemical composition of rocks. (3) Reflection and refraction of seismic waves help identify various discontinuities within the Earth.
Correct Answer:
A
— Only 1 and 3 are correct.
Explanation:
Since direct access to the Earth's interior is extremely limited, knowledge of its internal structure is derived mainly from indirect evidence such as seismic waves, gravitational data, and magnetic observations. Variations in the velocity of seismic waves are influenced not only by chemical composition but also by density, elasticity, and the physical state (solid/liquid) of the medium. Reflection and refraction of seismic waves are used to identify discontinuities such as the Mohorovičić (Moho), Gutenberg, and Lehmann discontinuities.
Question 18: Which of the following statement(s) is/are correct? (1) Upwelling generally increases marine biological productivity. (2) All warm ocean currents are associated with high fish production. (3) The distribution of fishery resources may be influenced by ocean circulation.
Correct Answer:
D
— 1 and 3 only
Explanation:
During upwelling, nutrient-rich deep water rises to the surface, increasing primary productivity and fishery resources. Ocean circulation also influences the distribution of fishery resources. However, not all warm ocean currents create regions of high fish production; therefore, the second statement is incorrect.
Question 19: Which of the following statement(s) is/are correct? (1) The energy available at each trophic level decreases along the food chain. (2) Decomposers convert dead organic matter back into simpler substances. (3) Decomposers recycle energy.
Correct Answer:
A
— 1 and 2 only
Explanation:
The energy available decreases at each trophic level, while decomposers convert dead organic matter into simpler inorganic substances, thereby facilitating nutrient recycling. Energy is not recycled; it is ultimately dissipated into the environment as heat. Therefore, the third statement is incorrect.
Question 20: Which of the following statement(s) is/are correct? (1) Ocean currents are influenced only by prevailing winds. (2) The Earth's rotation affects the direction of ocean currents. (3) Density differences caused by variations in temperature and salinity also influence deep ocean circulation.
Correct Answer:
B
— 2 and 3 only
Explanation:
Ocean currents are influenced not only by prevailing winds but also by the Coriolis effect, temperature, salinity, and density differences. Therefore, the first statement is incorrect because of the word "only," whereas the second and third statements are correct.
Question 21: Which of the following statement(s) is/are correct? (1) Vertical air mixing is relatively greater in the troposphere. (2) Therefore, most weather phenomena occur in this layer. (3) Convection in the stratosphere is more intense than in the troposphere.
Correct Answer:
A
— 1 and 2 only
Explanation:
Vertical convection and air mixing are more pronounced in the troposphere, which is why most weather phenomena such as clouds, rainfall, thunderstorms, and storms develop in this layer. In contrast, the stratosphere is relatively stable, with very little vertical convection. Therefore, the third statement is incorrect.
Question 22: Which of the following statement(s) is/are correct? (1) The distribution of monsoon rainfall depends only on the distance from the sea. (2) Mountain barriers influence the distribution of rainfall. (3) Changes in wind direction can also affect the regional distribution of rainfall.
Correct Answer:
B
— 2 and 3 only
Explanation:
Rainfall distribution depends on several factors, including topography, distance from the sea, wind direction, and local conditions. Therefore, the first statement is incorrect because of the word "only." The Himalayas and the Western Ghats are prominent examples.
Question 23: Which of the following statement(s) is/are correct? (1) All volcanic regions are located along plate boundaries. (2) Hotspot volcanism can also develop in the interior of tectonic plates. (3) The Hawaiian Islands are considered an example of hotspot volcanism.
Correct Answer:
C
— 2 and 3 only
Explanation:
Most volcanoes are associated with plate boundaries, but not all. Hotspot volcanism can also occur within the interiors of tectonic plates, and the Hawaiian Islands are a well-known example. The first statement is incorrect because of the word "Every."
Question 24: Which of the following pairs is not correctly matched?
Correct Answer:
D
— Sand dune — Glacial erosion
Explanation:
Sand dunes are primarily formed by wind deposition, not by glacial erosion. The other three pairs are correctly matched. Meanders develop through the combined action of river erosion and deposition.
Question 25: Which of the following statement(s) is/are correct? (1) The average density of the continental crust is lower than that of the oceanic crust. (2) The continental crust is predominantly granitic in composition, whereas the oceanic crust is predominantly basaltic. (3) The density difference between continental and oceanic crust influences the nature of subduction at convergent plate boundaries.
Correct Answer:
B
— 1, 2 and 3
Explanation:
The continental crust is relatively lighter and predominantly granitic, whereas the oceanic crust is denser and predominantly basaltic. Due to this density difference, the oceanic plate generally subducts beneath the continental plate at convergent boundaries. Therefore, all three statements are correct.
Question 26: Which of the following statement(s) is/are correct? (1) All cold ocean currents support equally rich fishing grounds. (2) Upwelling regions generally have high marine biological productivity. (3) The association of cold currents and upwelling may lead to high fish production in many regions.
Correct Answer:
C
— 2 and 3 only
Explanation:
Upwelling brings nutrient-rich water to the surface, increasing marine productivity and fishery resources. Many cold currents are associated with upwelling, but not all cold currents support equally rich fishing grounds. Therefore, the first statement is incorrect.
Question 27: Which of the following statements is the most appropriate regarding the biosphere?
Correct Answer:
A
— The biosphere is an open system where energy continuously enters, while matter is recycled.
Explanation:
Energy in the biosphere is primarily obtained from the Sun and flows in one direction, whereas matter is continuously recycled through various biogeochemical cycles. The other options are conceptually incorrect.
Question 28: Which of the following statement(s) is/are correct? (1) Energy flow in an ecosystem is unidirectional. (2) Nutrients are continuously recycled. (3) A major portion of the available energy at each trophic level is lost as heat.
Correct Answer:
B
— All of 1, 2 and 3 are correct.
Explanation:
In an ecosystem, energy flows in one direction from producers to consumers, and a significant portion of energy is lost as heat at each trophic level. In contrast, nutrients are continuously recycled through biogeochemical cycles.
Question 29: Which of the following statements regarding ocean currents is not correct?
Correct Answer:
D
— They are formed solely due to the Earth's rotation.
Explanation:
Ocean currents are formed by the combined influence of prevailing winds, the Earth's rotation, temperature, salinity, and coastal configuration. Therefore, attributing their formation solely to the Earth's rotation is incorrect. The other three statements are correct.
Question 30: Which of the following statement(s) is/are correct? (1) Vertical air mixing is relatively weak in the stratosphere. (2) For this reason, Most commercial jet aircraft generally fly in the lower stratosphere (3) All types of clouds form in the stratosphere.
Correct Answer:
A
— 1 and 2 only
Explanation:
The stratosphere is a relatively stable atmospheric layer where vertical convection and air mixing are limited. Therefore, most long-distance commercial jet aircraft prefer to fly in its lower part, where weather-related disturbances are comparatively fewer. Generally, clouds and other major weather phenomena occur in the troposphere; hence, the third statement is incorrect.
Question 31: Select the correct statement(s) regarding the Indian Monsoon. (1) Differential heating of land and sea creates a pressure gradient. (2) The Himalayas influence the path and distribution of monsoon winds. (3) The temperature of the Indian Ocean alone controls the monsoon.
Correct Answer:
A
— 1 and 2 only
Explanation:
The Indian Monsoon is a multi-factorial system. Land-sea thermal contrast, pressure gradients, the Himalayas, the Tibetan Plateau, jet streams, and oceanic conditions all play important roles. Therefore, the third statement is incorrect because of the word "alone."
Question 32: Which of the following statement(s) is/are correct? (1) Most earthquakes are associated with plate tectonic activities. (2) Some earthquakes may also be associated with volcanic activities. (3) All volcanic eruptions produce destructive earthquakes.
Correct Answer:
A
— 1 and 2 only
Explanation:
Most earthquakes in the world are caused by plate tectonic processes. Some earthquakes are also associated with volcanic activity and are known as volcanic earthquakes. However, not all volcanic eruptions generate destructive earthquakes; therefore, the third statement is incorrect.
Question 33: Which of the following statements regarding fluvial landforms is not the most appropriate?
Correct Answer:
D
— V-shaped valleys are mainly the result of river deposition.
Explanation:
V-shaped valleys are formed by intense vertical erosion in the upper course of a river, not by deposition. The statements regarding waterfalls, natural levees, and meanders are correct.
Question 34: Which of the following statement(s) is/are correct? (1) Mid-ocean ridges develop along divergent plate boundaries. (2) The process of seafloor spreading creates new oceanic crust. (3) The theory of seafloor spreading provided the scientific basis for the development of the theory of plate tectonics.
Correct Answer:
A
— All of 1, 2 and 3 are correct.
Explanation:
Mid-ocean ridges develop at divergent plate boundaries, where magma rises, cools, and forms new oceanic crust. This process is known as seafloor spreading. The concept provided scientific support for Wegener's Continental Drift Theory and later played a crucial role in the development of the theory of plate tectonics.
Question 35: Which of the following statement(s) is/are correct? (1) The velocity of P-waves decreases abruptly on entering the Earth's liquid outer core. (2) S-waves do not pass through the Earth's outer core. (3) The conclusion that the Earth's outer core is liquid was drawn solely on the basis of the behavior of S-waves.
Correct Answer:
A
— 1 and 2 only
Explanation:
P-waves travel through both solids and liquids, but their velocity drops abruptly when they enter the liquid outer core because of the change in physical properties. S-waves cannot propagate through liquids and therefore do not pass through the outer core. The inference that the outer core is liquid is based on several lines of seismic evidence, including the absence of S-waves, the reduction and refraction of P-waves, and seismic shadow zones.
Question 36: Which of the following statements is the most appropriate regarding the biosphere?
Correct Answer:
A
— It is the global zone of life where the lithosphere, hydrosphere, and atmosphere interact to support living organisms.
Explanation:
The biosphere is the zone where life exists through the interaction of the lithosphere, hydrosphere, and atmosphere. It cannot be confined solely to forests, oceans, or the atmosphere.
Question 37: In which of the following situations is upwelling most likely to occur?
Correct Answer:
B
— When cold, nutrient-rich deep water rises to the surface
Explanation:
Upwelling is the process by which cold, nutrient-rich deep water rises to the ocean surface. This promotes abundant fishery resources. The other options do not describe the process of upwelling.
Question 38: Which of the following statement(s) is/are correct? (1) The Sun is the primary source of energy in most ecosystems. (2) Energy flow is generally unidirectional, whereas nutrients undergo continuous cycling.
Correct Answer:
C
— Both 1 and 2 are correct.
Explanation:
In most ecosystems, the Sun is the primary source of energy, which producers convert into chemical energy through photosynthesis. However, in certain specialized ecosystems, such as deep-sea hydrothermal vents, chemical energy rather than solar energy serves as the primary source. Therefore, the use of the word "most" in Statement 1 is scientifically appropriate. Statement 2 is also correct because energy flows unidirectionally from producers to successive consumer levels and ultimately to decomposers, whereas nutrients are continuously recycled through biogeochemical cycles.
Question 39: Which of the following is the correctly matched pair of an ocean current and its classification?
Correct Answer:
A
— Kuroshio — Warm Current
Explanation:
The Kuroshio is a major warm current of the Pacific Ocean. The Peru, Labrador, and Benguela Currents are all cold currents.
Question 40: Which of the following statement(s) is/are correct? (1) The ozone layer is primarily located in the stratosphere. (2) It absorbs most of the Sun's harmful ultraviolet radiation.
Correct Answer:
B
— Both 1 and 2 are correct.
Explanation:
The ozone layer is located in the stratosphere and absorbs most of the harmful ultraviolet radiation from the Sun, thereby protecting life on Earth. Both statements are correct and closely related.
Question 41: Which of the following statements is correct regarding climate and weather?
Correct Answer:
D
— Climate represents the long-term average weather conditions of a region.
Explanation:
Weather refers to the short-term atmospheric conditions of a place, whereas climate represents the long-term average weather conditions, generally over a period of 30 years or more.
Question 42: Which of the following statements is correct regarding the epicentre of an earthquake?
Correct Answer:
C
— It is the point on the Earth's surface located directly above the focus.
Explanation:
The actual origin of an earthquake is the focus located within the Earth, whereas the point directly above it on the Earth's surface is known as the epicentre. The other options reflect conceptual misunderstandings.
Question 43: Which of the following statement(s) is/are correct? (1) New oceanic crust is generally formed at divergent plate boundaries. (2) Crustal destruction or recycling may occur at convergent plate boundaries.
Correct Answer:
A
— Both 1 and 2 are correct.
Explanation:
At divergent boundaries, magma rises and forms new oceanic crust. At convergent boundaries, subduction causes older crust to be recycled into the mantle. Both statements represent the fundamental principles of Plate Tectonics.
Question 44: Which of the following landforms is primarily formed by the solution action of groundwater?
Correct Answer:
B
— Karst topography
Explanation:
Karst topography develops through the chemical solution of soluble rocks such as limestone by groundwater. Deltas and alluvial fans are formed by river deposition, while moraines are formed by materials deposited by glaciers. UPSC often tests the correct matching of geomorphic processes with their associated landforms. Mnemonic: Limestone + Solution = Karst.
Question 45: Which of the following statement(s) is/are correct? (1) The average density of the Earth is greater than the average density of its crust. (2) This difference is mainly due to the greater concentration of heavy elements toward the Earth's core.
Correct Answer:
D
— Both 1 and 2 are correct, and 2 is the correct explanation of 1.
Explanation:
The Earth's average density is approximately 5.5 g/cm³, whereas the average density of the crust is significantly lower. This is primarily because the Earth's interior, especially the core, is dominated by heavy elements such as iron and nickel.
Question 46: Which of the following statement(s) is/are correct? (1) Ocean currents contribute to the global redistribution of heat. (2) Ocean currents may also influence the distribution of fishery resources.
Correct Answer:
B
— Both 1 and 2 are correct.
Explanation:
Ocean currents redistribute heat across the globe and strongly influence regional climates. They also affect fisheries by transporting nutrients and promoting upwelling of nutrient-rich deep waters, thereby increasing marine productivity.
Question 47: Which of the following statements is the most appropriate regarding volcanic regions?
Correct Answer:
A
— Fertile soils may develop in volcanic regions.
Explanation:
Soils formed from the weathering of volcanic ash are generally highly fertile, resulting in intensive agriculture and dense human settlements in many volcanic regions. The other options are incorrect because they use absolute terms such as "all," "only," and "never."
Question 48: Which of the following statement(s) is/are correct? (1) The existence of the biosphere depends on the interaction among the lithosphere, hydrosphere, and atmosphere. (2) The biosphere is limited only to terrestrial organisms.
Correct Answer:
A
— Only 1 is correct.
Explanation:
The biosphere is the zone where life exists through the interaction of the lithosphere, hydrosphere, and atmosphere. It includes terrestrial, aquatic, and aerial organisms. Therefore, Statement 1 is correct, whereas Statement 2 is incorrect because the biosphere is not confined only to terrestrial life.
Question 49: Which of the following is NOT the correct pair of an ocean current and its effect?
Correct Answer:
D
— Labrador Current — Warm and humid coastal influence
Explanation:
The Labrador Current is a cold ocean current; therefore, describing it as producing a warm coastal influence is incorrect. The Peru Current is also a cold current, whereas the Gulf Stream and the Kuroshio Current are warm currents.
Question 50: Which of the following statement(s) is/are correct? (1) Temperature generally increases with altitude in the stratosphere. (2) The primary reason for this is the absorption of ultraviolet radiation by ozone.
Correct Answer:
A
— Both 1 and 2 are correct.
Explanation:
In the stratosphere, the ozone layer absorbs the Sun's ultraviolet radiation, causing temperature to increase with altitude. This distinguishes it from the troposphere, where temperature generally decreases with altitude.
Question 51: Which of the following factors is the most important for the onset of the monsoon?
Correct Answer:
B
— Pressure gradient created by the differential heating of land and water
Explanation:
The fundamental cause of the Indian monsoon is the pressure gradient generated by the differential heating of land and sea. The Himalayas and jet streams also play significant roles, but neither alone can fully explain the monsoon.
Question 52: Which of the following statement(s) is/are correct? (1) All earthquakes occur only along plate boundaries. (2) Earthquakes can also occur within tectonic plates.
Correct Answer:
C
— Only 2 is correct.
Explanation:
Most earthquakes occur along plate boundaries, but not all. Some earthquakes also originate within tectonic plates, such as those recorded in certain interior regions of India. Hence, Statement 1 is incorrect because of the word "all."
Question 53: Which of the following statement(s) is/are correct? (1) The erosional work of a river is generally more effective in its upper course. (2) The depositional work of a river is generally more dominant in its lower course.
Correct Answer:
A
— Both 1 and 2
Explanation:
In the upper course of a river, the steep gradient leads to intense erosion. In the lower course, the reduced gradient and lower velocity promote the deposition of sediments. Although both processes occur throughout the river's course, their dominance varies from one section to another.
Question 54: Which of the following statements best describes the Theory of Plate Tectonics?
Correct Answer:
D
— The lithosphere is divided into several plates that move over the asthenosphere.
Explanation:
According to the Theory of Plate Tectonics, the lithosphere is divided into several tectonic plates that move gradually over the relatively ductile asthenosphere beneath it. These plates may consist of both continental and oceanic crust.
Question 55: Choose the correct answer regarding the following statements: (1) Seismic waves are considered the most important indirect source for studying the deep interior of the Earth. (2) The nature of the Earth's internal layers is inferred on the basis of changes in the velocity and behavior of P-waves.
Correct Answer:
B
— Both 1 and 2 are correct.
Explanation:
Direct access to the Earth's interior is extremely limited. Therefore, seismic waves constitute the most important indirect source for understanding the Earth's internal structure. Variations in the velocity, reflection, and refraction of seismic waves—especially P-waves, along with the absence of S-waves in the outer core—help infer the composition and physical state of different internal layers.
Question 56: Which of the following pairs is correctly matched?
Correct Answer:
C
— Water Cycle — Evaporation, Condensation, and Precipitation
Explanation:
The water cycle consists primarily of evaporation, condensation, and precipitation. Most weather phenomena occur in the troposphere, the outer core is in a liquid state, and a delta is formed by river deposition, not by glacial erosion.
Question 57: Which of the following best describes an active volcano?
Correct Answer:
A
— A volcano that has erupted during historical times or shows signs of likely future eruptions.
Explanation:
An active volcano is one that has erupted during historical times or shows evidence of continuing volcanic activity and is likely to erupt again. Dormant volcanoes are temporarily inactive but may erupt in the future, whereas extinct volcanoes are not expected to erupt again.
Question 58: Which of the following is an abiotic component of the biosphere?
Correct Answer:
B
— Soil
Explanation:
Soil is an abiotic component of the biosphere, whereas microorganisms, vegetation, and animals are biotic components. Ecosystems function through the interaction of both living and non-living components.
Question 59: What is a major effect of the Gulf Stream ocean current?
Correct Answer:
D
— Making the coastal regions of Western Europe relatively warmer.
Explanation:
The Gulf Stream is a warm ocean current that transports heat toward the North Atlantic. As a result, the coastal regions of Western Europe experience a relatively warmer and more temperate climate than other regions at similar latitudes.
Question 60: Which of the following is a major characteristic of the troposphere?
Correct Answer:
A
— Most weather phenomena occur in this layer.
Explanation:
The troposphere is the lowest layer of the atmosphere, and most weather phenomena such as clouds, rainfall, and storms occur within it. The ozone layer is primarily located in the stratosphere, and temperature generally decreases with increasing altitude in the troposphere.
Question 61: The local wind known as "Loo" generally blows in India during which season?
Correct Answer:
C
— Summer Season
Explanation:
The Loo is an extremely hot and dry local wind that blows over northwestern and northern India during the summer season. It is not associated with the monsoon or the winter season.
Question 62: The Richter Scale primarily measures which of the following?
Correct Answer:
B
— Magnitude of an earthquake
Explanation:
The Richter Scale measures the magnitude of an earthquake, which indicates the amount of energy released at its source. The intensity of an earthquake, which reflects its observed effects and damage, is commonly measured using the Modified Mercalli Intensity (MMI) Scale.
Question 63: Which of the following landforms is primarily the result of glacial erosion?
Correct Answer:
D
— U-shaped Valley
Explanation:
A U-shaped valley is formed through extensive erosion by glaciers. A delta is formed by river deposition, an alluvial fan by deposition on mountain slopes, and sand dunes by wind action.
Question 64: Which of the following rocks is formed directly by the cooling of magma or lava?
Correct Answer:
A
— Igneous Rock
Explanation:
Igneous rocks are formed by the cooling and solidification of magma or lava. Sedimentary rocks are formed through the deposition and compaction of sediments, whereas metamorphic rocks are formed when pre-existing rocks undergo changes due to heat and pressure. "Stratified" is not a primary rock classification.
Question 65: Select the correct answer based on the following statements. (1) The age of the Earth has been determined primarily through the radiometric dating method. (2) The rate of decay of radioactive elements is considered constant over time.
Correct Answer:
C
— Both Statements 1 and 2 are correct.
Explanation:
The age of the Earth (approximately 4.54 billion years) has been determined mainly through radiometric dating. This method is based on the constant decay rate of radioactive isotopes. Therefore, both statements are correct.
Question 66: Which of the following cloud types is generally associated with thunderstorms, lightning, and heavy rainfall?
Correct Answer:
D
— Cumulonimbus Cloud
Explanation:
Cumulonimbus clouds are vertically developed clouds formed due to strong convection. They are associated with thunderstorms, lightning, heavy rainfall, squalls, and sometimes hailstorms or tornadoes.
Question 67: Which of the following best describes the biosphere?
Correct Answer:
A
— The zone where the lithosphere, hydrosphere, and atmosphere interact to support life.
Explanation:
The biosphere is the zone of the Earth where the lithosphere, hydrosphere, and atmosphere interact to provide suitable conditions for life. The other options unnecessarily restrict its extent.
Question 68: Which of the following ocean currents is a cold current?
Correct Answer:
C
— Labrador Current
Explanation:
The Labrador Current is a cold ocean current that flows southward from the Arctic Ocean along the coast of eastern Canada. The Gulf Stream, Kuroshio Current, and Brazil Current are warm ocean currents.
Question 69: Which of the following gases is present in the largest proportion in the atmosphere?
Correct Answer:
D
— Nitrogen
Explanation:
The atmosphere consists of approximately 78% nitrogen, 21% oxygen, and the remaining fraction comprises other gases. Although carbon dioxide is present in a very small proportion, it is extremely important from a climatic perspective.
Question 70: What is the primary cause of the change of seasons on the Earth?
Correct Answer:
A
— The tilt of the Earth's axis and its revolution around the Sun
Explanation:
The change of seasons results from the combined effect of the Earth's axial tilt of about 23½° and its revolution around the Sun. Neither the variation in distance nor the Earth's rotation alone is responsible.
Question 71: What is the molten material erupted from a volcano called after it reaches the Earth's surface?
Correct Answer:
B
— Lava
Explanation:
Molten rock beneath the Earth's surface is called magma. Once it erupts onto the Earth's surface, it is known as lava. Basalt is a common igneous rock formed by the cooling and solidification of basaltic lava.
Question 72: Which of the following landforms is primarily formed by river deposition?
Correct Answer:
C
— Delta
Explanation:
A delta is formed by the deposition of sediments carried by a river at the coast of a sea or lake. V-shaped valleys, waterfalls, and gorges are primarily erosional landforms.
Question 73: Who proposed the Continental Drift Theory?
Correct Answer:
A
— Alfred Wegener
Explanation:
Alfred Wegener proposed the Continental Drift Theory in 1912, suggesting that all continents were once joined together as a supercontinent called Pangaea, which later broke apart and drifted to their present positions. Arthur Holmes later proposed mantle convection as a possible driving mechanism, Harry Hess developed the Seafloor Spreading Theory, and James Hutton is regarded as the Father of Modern Geology.
Question 74: Which of the following types of seismic waves cannot travel through a liquid medium?
Correct Answer:
D
— S (Secondary) Wave
Explanation:
S (Secondary) waves can travel only through solid materials and cannot pass through liquids. In contrast, P (Primary) waves can travel through solids, liquids, and gases. This property provided crucial evidence that the Earth's outer core is in a liquid state. Although Surface waves (including Love waves) travel along the Earth's surface, they are not used to determine the internal liquid layers of the Earth.
Question 75: Which of the following statements regarding the internal structure of the Earth is correct?
Correct Answer:
B
— The Earth's mantle is located between the crust and the core.
Explanation:
The mantle is the thickest layer of the Earth and lies between the crust and the core. The crust is the thinnest layer, the outer core is in a liquid state, and the inner core remains solid due to extremely high pressure.
Question 76: Assertion (A): All climatic characteristics of the Earth are determined solely by latitude. Reason (R): Altitude, ocean currents, topography, and pressure–wind systems also influence climate.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
Latitude is an important climatic control but not the only one. Climate is also influenced by altitude, ocean currents, topography, prevailing winds, and pressure systems. Hence, the assertion is incorrect while the reason is correct.
Question 77: Assertion (A): Oceans act as heat reservoirs in the Earth's climate system. Reason (R): Due to the high specific heat of water, oceans can absorb and release large amounts of heat relatively slowly.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
Oceans regulate Earth's climate by absorbing and releasing heat gradually. Their high specific heat enables them to function as major heat reservoirs. Therefore, the reason correctly explains the assertion.
Question 78: Assertion (A): Physical weathering occurs only in cold regions. Reason (R): In deserts, physical weathering also occurs due to thermal expansion and contraction.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
Physical weathering occurs in both cold and arid regions. In deserts, repeated heating and cooling cause thermal expansion and contraction of rocks, resulting in mechanical weathering.
Question 79: Assertion (A): Every earthquake is destructive. Reason (R): Many earthquakes are not even perceived by humans.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because most earthquakes are too weak to cause damage and many are detected only by sensitive instruments. The reason is correct.
Question 80: Assertion (A): Energy flows unidirectionally in the biosphere, whereas nutrients undergo cycling. Reason (R): Energy is ultimately dissipated into the environment as heat, whereas matter is recycled through biogeochemical cycles.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
Energy flows in one direction from the Sun through trophic levels and is progressively lost as heat. Nutrients such as carbon, nitrogen, phosphorus, and water are continuously recycled through biogeochemical cycles. Therefore, the reason correctly explains the assertion.
Question 81: Assertion (A): Warm ocean currents generally favour higher rainfall in the regions they influence. Reason (R): Rainfall does not depend solely on ocean currents.
Correct Answer:
B
— Both A and R are correct, but R is not the correct explanation of A.
Explanation:
Warm ocean currents generally enhance evaporation and atmospheric moisture, which favours rainfall. However, rainfall also depends on prevailing winds, pressure systems, topography, and atmospheric circulation. Thus, both the assertion and the reason are correct, but the reason does not fully explain the assertion.
Question 82: Assertion (A): Vertical convection in the stratosphere is more intense than in the troposphere. Reason (R): In the stratosphere, temperature increases with altitude, thereby increasing atmospheric stability.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because the stratosphere is highly stable and suppresses vertical convection. The reason is correct because temperature inversion increases atmospheric stability.
Question 83: Assertion (A): If the average temperature of a region increases, rainfall there will necessarily increase as well. Reason (R): Air can hold more water vapour at higher temperatures.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because an increase in temperature alone does not ensure increased rainfall. Moisture availability, uplift, condensation, and atmospheric circulation are also essential. The reason is correct because warmer air can hold more water vapour, but this alone does not guarantee precipitation.
Question 84: Assertion (A): Orogenic activity and volcanic activity can occur simultaneously in a region. Reason (R): At oceanic–continental convergent plate boundaries, subduction can drive both processes.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The assertion is correct because mountain building and volcanic activity commonly occur together at convergent plate boundaries. The reason correctly explains the assertion, as subduction generates magma while compressional forces produce mountain building.
Question 85: Assertion (A): The present model of the Earth's internal structure is primarily based on the analysis of seismic waves. Reason (R): The variation in the velocity of seismic waves is caused only by temperature.
Correct Answer:
C
— A is correct, but R is incorrect.
Explanation:
The assertion is correct because most of our knowledge of the Earth's internal structure has been obtained through the study of the velocity, reflection, refraction, and propagation of seismic waves. The reason is incorrect because seismic wave velocity depends not only on temperature but also on elasticity, density, pressure, and whether the medium is solid or liquid.
Question 86: Assertion (A): The direction of ocean currents is determined solely by the Earth's rotation. Reason (R): Prevailing winds, the Coriolis effect, continental barriers, and differences in temperature and salinity influence ocean currents.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because ocean currents are influenced by multiple factors, including prevailing winds, the Coriolis effect, continental barriers, and differences in temperature and salinity. The Earth's rotation alone does not determine their direction. Therefore, the reason is correct.
Question 87: Assertion (A): The Earth's energy balance is extremely important for the climate system. Reason (R): If there is a long-term imbalance between incoming and outgoing energy, global climate may change.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The assertion is correct because the Earth's energy balance regulates global temperature and climate. A persistent imbalance between incoming solar radiation and outgoing terrestrial radiation can lead to long-term climate change. Therefore, the reason correctly explains the assertion.
Question 88: Assertion (A): The presence of water is essential for all types of weathering processes. Reason (R): Thermal expansion and contraction can also cause the physical disintegration of rocks.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because mechanical weathering can occur without water, especially in arid regions through thermal expansion and contraction of rocks. Therefore, the reason is correct.
Question 89: Assertion (A): The epicentre of every earthquake is located beneath the Earth's surface. Reason (R): The focus (hypocentre) of an earthquake is located within the Earth.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because the epicentre is the point on the Earth's surface directly above the focus (hypocentre), whereas the focus (hypocentre) lies beneath the Earth's surface. Therefore, the reason is correct.
Question 90: Assertion (A): The biosphere functions as an open system. Reason (R): The biosphere exchanges energy with the Sun and matter with the atmosphere, lithosphere, and hydrosphere.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The assertion is correct because the biosphere continuously exchanges both energy and matter. It receives energy from the Sun and exchanges matter with the atmosphere, hydrosphere, and lithosphere through biogeochemical cycles. Hence, the reason correctly explains the assertion.
Question 91: Assertion (A): Warm ocean currents can increase the likelihood of relatively higher humidity and rainfall in coastal regions. Reason (R): Warm currents facilitate a higher rate of evaporation from seawater.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
Warm ocean currents enhance evaporation, increasing atmospheric moisture and humidity. This raises the likelihood of cloud formation and rainfall in adjacent coastal regions. Therefore, the reason correctly explains the assertion.
Question 92: Assertion (A): Temperature decreases with increasing altitude in the stratosphere. Reason (R): The ozone layer in the stratosphere absorbs ultraviolet radiation.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because temperature increases with altitude in the stratosphere due to the absorption of ultraviolet radiation by the ozone layer. Therefore, the reason is correct.
Question 93: Assertion (A): The amount of rainfall in a region does not depend solely on the availability of water vapour. Reason (R): Even if sufficient water vapour is available, rainfall will not occur unless air rises and condensation takes place.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The assertion is correct because the availability of water vapour alone does not ensure rainfall. Air must rise, cool, and condense to form precipitation. Therefore, the reason correctly explains the assertion.
Question 94: Assertion (A): Only mid-ocean ridges are formed at all divergent plate boundaries. Reason (R): Continental rift valleys can also develop at divergent plate boundaries.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because divergent plate boundaries occur both in oceans and on continents. While mid-ocean ridges form at oceanic divergent boundaries, continental rift valleys (e.g., the East African Rift) form where continental plates diverge. Therefore, the reason is correct.
Question 95: Assertion (A): The temperature inside the Earth generally increases with depth. Reason (R): The geothermal gradient remains constant at the same rate at all depths.
Correct Answer:
C
— A is correct, but R is incorrect.
Explanation:
The assertion is correct because the Earth's temperature generally increases with depth. However, the reason is incorrect because the geothermal gradient is not uniform throughout the Earth's interior. In the upper crust, it averages about 25–30°C per km, but it varies significantly with increasing depth toward the mantle and the core.
Question 96: Assertion (A): The differential thermal behaviour of land and sea plays a role in the origin of the monsoon. Reason (R): The direction of monsoon winds changes twice during the year.
Correct Answer:
B
— Both A and R are correct, but R is not the correct explanation of A.
Explanation:
The assertion is correct because the differential heating of land and sea contributes to the development of seasonal pressure differences that influence the origin of the monsoon. The reason is also correct because monsoon winds reverse their direction seasonally, giving rise to the Southwest and Northeast Monsoons. However, this seasonal reversal is a characteristic of the monsoon system rather than the reason for its origin. Therefore, the reason does not correctly explain the assertion.
Question 97: Assertion (A): Chemical alteration of rocks is essential in all weathering processes. Reason (R): Physical weathering may involve only the mechanical disintegration of rocks.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because weathering may be physical, chemical, or biological, and chemical alteration is not involved in every type of weathering. The reason is correct because physical weathering involves only the mechanical breakdown of rocks without changing their chemical composition. Therefore, option D is correct.
Question 98: Assertion (A): The vertical distribution of temperature is not uniform across the different layers of the atmosphere. Reason (R): Most of the atmospheric water vapour is found in the troposphere.
Correct Answer:
B
— Both A and R are correct, but R is not the correct explanation of A.
Explanation:
The assertion is correct because temperature changes differently in the troposphere, stratosphere, mesosphere, and thermosphere. The reason is also correct because almost all atmospheric water vapour is concentrated in the troposphere. However, this is not the primary reason for the different temperature patterns among atmospheric layers, which are mainly controlled by varying mechanisms of heat absorption and energy transfer.
Question 99: Assertion (A): The biosphere is confined only to land and oceans. Reason (R): Microorganisms can also be found in the lower part of the atmosphere.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because the biosphere includes not only land and oceans but also the lower atmosphere and parts of the lithosphere where life exists. The reason is correct because microorganisms are found in the lower atmosphere. Therefore, option D is correct.
Question 100: Assertion (A): The thickness of the troposphere is greater at the Equator than at the poles. Reason (R): The ozone layer in the stratosphere absorbs most of the Sun's ultraviolet radiation.
Correct Answer:
B
— Both A and R are correct, but R is not the correct explanation of A.
Explanation:
The assertion is correct because the troposphere is about 16–18 km thick over the Equator and about 8–10 km thick over the poles. The reason is also correct because the ozone layer absorbs most of the Sun's ultraviolet radiation. However, this does not explain the variation in the thickness of the troposphere. The greater thickness over the Equator is mainly due to stronger solar heating and vigorous vertical convection.
Question 101: Assertion (A): Cold ocean currents generally reduce the temperature of adjacent coastal regions. Reason (R): They bring relatively colder water from higher latitudes towards lower latitudes.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The assertion is correct because cold ocean currents lower the temperature of nearby coastal regions. The reason is also correct because most cold currents transport cold water from higher to lower latitudes, thereby cooling adjacent coastal areas. Hence, the reason correctly explains the assertion.
Question 102: Assertion (A): All seismic waves pass through the Earth's liquid outer core. Reason (R): S-waves do not travel through a liquid medium.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The assertion is incorrect because only P-waves pass through the Earth's liquid outer core, whereas S-waves cannot travel through liquids. The reason is correct and explains why the assertion is incorrect.
Question 103: Assertion (A): The daily variation in temperature is greater over land than over the sea. Reason (R): Water has a higher specific heat capacity than land.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The assertion is correct because land heats up and cools down more rapidly than water. The reason is also correct because water has a higher specific heat capacity than land, causing it to warm and cool more slowly. Therefore, the reason correctly explains the assertion.
Question 104: Assertion (A): Continental–continental convergence leads to the formation of massive fold mountains. Reason (R): Since both continental plates have relatively low density, one plate does not easily subduct beneath the other.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The assertion is correct because the collision of two continental plates produces intense compressional forces that give rise to massive fold mountains such as the Himalayas. The reason is also correct because continental plates have relatively low density and therefore resist subduction. Instead, they undergo compression, folding, and uplift. Hence, the reason correctly explains the assertion.
Question 105: Assertion (A): The average density of the Earth is greater than the density of its outer layers. Reason (R): Heavier elements such as iron and nickel are predominantly concentrated towards the Earth's core.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The assertion is correct because the Earth's average density (about 5.5 g/cm³) is significantly higher than the density of its outer layers, especially the crust. The reason is also correct because dense elements such as iron and nickel are concentrated mainly in the Earth's core, which raises the Earth's overall average density. Therefore, the reason correctly explains the assertion.
Question 106: Assertion (A): Temperature plays an important role in the formation of rainfall. Reason (R): Water vapour, condensation nuclei, and suitable atmospheric conditions are also essential for rainfall.
Correct Answer:
B
— Both A and R are correct, but R is not the correct explanation of A.
Explanation:
The assertion is correct because temperature influences evaporation and condensation, which are fundamental to rainfall formation. The reason is also correct because water vapour, condensation nuclei, and suitable atmospheric conditions are also essential for rainfall. However, the reason lists additional necessary conditions rather than explaining why temperature plays an important role. Therefore, Option B is correct.
Question 107: Assertion (A): The ozone layer absorbs a major portion of the Sun's harmful ultraviolet radiation. Reason (R): The highest concentration of ozone is found in the stratosphere.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The assertion is correct because the ozone layer absorbs most of the Sun's harmful ultraviolet (UV-B and almost all UV-C) radiation. The reason is also correct because the highest concentration of atmospheric ozone is found in the stratosphere, where it forms the ozone layer responsible for absorbing ultraviolet radiation. Therefore, the reason correctly explains the assertion.
Question 108: Assertion (A): The distribution of atmospheric pressure influences the formation of winds. Reason (R): The Earth's rotation also affects the direction of winds.
Correct Answer:
B
— Both A and R are correct, but R is not the correct explanation of A.
Explanation:
The Assertion is correct because winds blow from areas of high pressure to areas of low pressure. The reason is also correct because the Earth's rotation produces the Coriolis effect, which changes the direction of winds. However, this is not the direct cause of wind formation. Therefore, Option B is correct.
Question 109: Assertion (A): The biosphere is confined only to land areas. Reason (R): Living organisms are also found in the oceans and in the lower part of the atmosphere.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The Assertion is incorrect because the biosphere includes land, water, and the lower part of the atmosphere. The reason is correct. Therefore, Option D is correct.
Question 110: Assertion (A): Most earthquakes are caused by the movement of tectonic plates. Reason (R): All earthquakes are caused only by volcanic activities.
Correct Answer:
C
— A is correct, but R is incorrect.
Explanation:
The Assertion is correct because most major earthquakes are associated with plate tectonics. The reason is incorrect because not all earthquakes are caused by volcanic activities. Therefore, Option C is correct.
Question 111: Assertion (A): Ocean currents influence the global climate. Reason (R): They redistribute heat from one region to another.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The Assertion is correct because ocean currents influence the temperature, rainfall, and climate of coastal regions. The reason is also correct because warm and cold currents redistribute heat across the globe. This directly explains the Assertion. Therefore, Option A is correct.
Question 112: Assertion (A): Most weather-related phenomena occur in the stratosphere. Reason (R): Most water vapour and dust particles are found in the troposphere.
Correct Answer:
D
— A is incorrect, but R is correct.
Explanation:
The Assertion is incorrect because most weather phenomena occur in the troposphere. The reason is correct because the abundance of water vapour and dust particles in this layer makes weather processes possible. Therefore, Option D is correct.
Question 113: Assertion (A): Both weathering and erosion play a role in the formation of landforms. Reason (R): Weathering breaks rocks down without transporting them, whereas erosion also transports the weathered material.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The assertion is correct because landforms develop through processes such as weathering, erosion, transportation, and deposition. The reason is also correct because weathering disintegrates rocks in situ, while erosion removes and transports the weathered material. These complementary roles explain how both processes contribute to landform development. Therefore, Option A is correct.
Question 114: Assertion (A): Most volcanoes are located along tectonic plate boundaries. Reason (R): Some volcanoes also develop in hotspot regions.
Correct Answer:
B
— Both A and R are correct, but R is not the correct explanation of A.
Explanation:
The Assertion is correct because most of the world's volcanoes are found along convergent and divergent plate boundaries. The reason is also correct because some volcanoes develop away from plate boundaries in hotspot regions (e.g., the Hawaiian Islands). However, this does not explain why most volcanoes occur along plate boundaries; rather, it mentions an exception. Therefore, Option B is correct.
Question 115: Assertion (A): Seismic waves are considered an important source for studying the internal structure of the Earth. Reason (R): Changes in the velocity and behavior of seismic waves help infer the properties of the Earth's different internal layers.
Correct Answer:
A
— Both A and R are correct, and R is the correct explanation of A.
Explanation:
The Assertion is correct because the direct study of the Earth's interior is extremely limited; therefore, seismic waves are the most reliable indirect source of information. The reason is also correct because the nature of layers such as the crust, mantle, and core is inferred from the velocity, refraction, reflection, and obstruction of P-waves and S-waves. Hence, the reason directly explains the Assertion. Therefore, Option A is correct.