Class 6 Social Science Chapter 2 Oceans and Continents

Key Concept: Oceans and Continents Distribution

c) Northern Hemisphere
[Solution Description]
The Northern Hemisphere has more landmass compared to the Southern Hemisphere, which is mostly covered by oceans. Approximately 60% of the Earth’s land is in the Northern Hemisphere, while the Southern Hemisphere is about 81% water.

Key Concept: Ocean Distribution, Marine Life

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion (A) states that the Southern Ocean is considered a separate ocean because of its distinct marine ecosystem and unique currents. This is true as the Southern Ocean has been recognized for its unique biological and physical characteristics, including the Antarctic Circumpolar Current, which isolates it from other oceans. The Reason (R) explains that the Southern Ocean encircles Antarctica and supports marine life adapted to extreme cold conditions. This is also true, as the Southern Ocean’s frigid waters host species like krill, penguins, and seals that are not found in such densities elsewhere. The Reason correctly explains why the Southern Ocean is distinct, linking its geographical and ecological uniqueness to its classification as a separate ocean.

Key Concept: Ocean Connectivity

c) Because seawater flows continuously across them
[Solution Description]
The boundaries between oceans are man-made and not natural because seawater flows continuously across them, connecting all oceans into one global system. Marine life also migrates freely across these boundaries, indicating no real separation.

Key Concept: Earth as the ‘Blue Planet’

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the Earth appears blue from space due to its water-covered surface. This is true as per the syllabus, which mentions that water covers almost three-fourths of the Earth’s surface. The reason correctly explains why the Earth appears blue—because water reflects blue light and dominates the planet’s surface area. Both statements are factually accurate, and the reason logically justifies the assertion.

Key Concept: Continents, Landmass Distribution

c) 10% of the total land
[Solution Description]
Given that land covers one-fourth (25%) of the Earth’s surface and Antarctica occupies 10% of this land area, we first need to find 10% of 25%. Mathematically, this translates to: $0.10 \times 0.25 = 0.025$ or 2.5%. Therefore, Antarctica covers 2.5% of the Earth’s total surface. However, since the question asks for the fraction of the land covered, Antarctica covers 10% of the total land area.

Key Concept: Water Coverage, Oceans and Continents

c) 75 parts
[Solution Description]
To find out how much of the Earth’s surface is covered by water when it is given as three-fourths, we can calculate this fraction in terms of 100 equal parts. Three-fourths means 3 parts out of 4. To convert this to a percentage or parts per hundred: $(3/4) \times 100 = 75$ parts. So, 75 out of 100 equal parts of the Earth’s surface are covered with water.

Key Concept: Ocean coverage, Earth’s surface composition

c) 60%
[Solution Description]
First, calculate the total water coverage: 72% of Earth’s surface. Oceans make up $\frac{5}{6}$ of this water coverage. So, ocean coverage = $72 \times \frac{5}{6} = 60%$ of Earth’s surface.

Key Concept: Ocean interconnection, Pollution impact

c) 10 years
[Solution Description]
Let current pollution = P. Annual increase = 15%, so pollution after n years = $P(1.15)^n$. We need $P(1.15)^n = 2P$. Solving: $(1.15)^n = 2$. Taking natural logs: $n = \frac{\ln(2)}{\ln(1.15)} ≈ 4.96$ years. Adding the 5-year circulation time gives ≈ 10 years total.

Key Concept: Major Oceans

c) Mediterranean Sea
[Solution Description]
The five major oceans are the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Arctic Ocean, and the Southern (Antarctic) Ocean. The Mediterranean Sea is not classified as a major ocean.

Key Concept: Continents classification, Island vs. Continent

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that Greenland is the largest island and not a continent due to its size not meeting the continental threshold. This is true as per the syllabus, which mentions Greenland as the largest island. The Reason explains the distinction between continents and islands based on size and geological characteristics, which is also accurate as per the syllabus. The Reason correctly explains why Greenland is an island and not a continent, as it directly links the size criterion to the classification.

Key Concept: Concept: Relative Sizes of Continents

c) Africa is larger than North America
[Solution Description]
According to the syllabus, Africa is larger than North America. Similarly, Antarctica is larger than Australia.

Key Concept: Largest Island

d) Greenland
[Solution Description]
The syllabus mentions that Greenland is the largest island in the world. It is so large that you would have to add the areas of the 10 largest states of India to match its size.

Key Concept: Ocean Connectivity

a) Yes, they are fully connected
[Solution Description]
The syllabus mentions that oceans are interconnected. Therefore, there are no complete separations between them; they form one continuous body of water.

Key Concept: Oceans and Continents, Distribution of Land and Water

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The assertion states that the Northern Hemisphere has more landmass than the Southern Hemisphere, which is true as per the syllabus (“The Northern Hemisphere has more land than the Southern Hemisphere.”). The reason attributes this unequal distribution to geological history and plate tectonics. While the syllabus does not explicitly mention plate tectonics as the cause, it implies uneven distribution without specifying the exact mechanism. Thus, the Reason is plausible but not directly confirmed by the syllabus. Therefore, while Assertion is true, the Reason cannot be definitively verified as the correct explanation based on the given syllabus content.

Key Concept: Islands, Continents

c) Australia lies on its own continental shelf and tectonic plate.
[Solution Description]
Islands are defined as landmasses entirely surrounded by water but smaller than continents. Continents are also surrounded by water, but they are significantly larger and geologically distinct, often with their own tectonic plates.
Greenland, although large, does not meet the geological criteria for a continent (e.g., lacking a distinct tectonic plate). Australia, however, sits on its own continental plate, qualifies as the smallest continent, and is thus not considered an island despite being surrounded by water.

Key Concept: Human Impact on Oceans

c) Choking and endangering marine life
[Solution Description]
Plastic pollution severely affects marine ecosystems by choking marine life, disrupting food chains, and degrading habitats. Millions of tonnes of plastic waste dumped annually lead to long-term environmental damage, threatening biodiversity and human food sources.

Key Concept: Oxygen Production

c) Ocean flora
[Solution Description]
According to the text: “more than half of the world’s oxygen is produced by the oceans’ flora.”

Key Concept: Oceans and Climate

a) By absorbing and distributing solar heat
[Solution Description]
Oceans play a critical role in regulating Earth’s climate by controlling temperature through heat absorption and distribution, generating rainfall via the water cycle, and producing oxygen through marine flora. These processes collectively stabilize atmospheric conditions and sustain life.

Key Concept: Distribution of Water and Land, Hemispheric Differences

c) Assertion is true, but Reason is false.
[Solution Description]
The Assertion states that the Southern Hemisphere has more water coverage than the Northern Hemisphere, which is correct as per geographical data (~81\% water vs. ~61\% in the Northern Hemisphere). However, the Reason claims that large landmasses like Antarctica reduce the land area in the Southern Hemisphere, which is incorrect because Antarctica is a significant landmass, but the high water proportion is due to the vast expanse of oceans like the Pacific and Atlantic. Thus, the Assertion is true, but the Reason is false.

Key Concept: Land-water distribution impact

d) Water-rich Southern Hemisphere has milder temperature fluctuations.
[Solution Description]
The Northern Hemisphere’s larger landmass leads to greater temperature variations (continental climate), while the Southern Hemisphere’s dominant water coverage ensures maritime climates with stable temperatures. Oceans absorb and release heat slowly, moderating temperatures, whereas land heats and cools rapidly, causing extremes.

Key Concept: Oceans and Continents

c) Continents
[Solution Description]
As per the syllabus, large continuous expanses of land are referred to as continents.

Key Concept: Distribution of Oceans and Continents

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that the Southern Hemisphere has a larger proportion of water than land, which is true because approximately 80\% of the Southern Hemisphere is covered by oceans (e.g., Pacific, Atlantic, Indian, and Southern Oceans). The Reason claims that most large landmasses are in the Northern Hemisphere, which is also correct (e.g., Asia, Europe, North America). Furthermore, the concentration of land in the Northern Hemisphere directly explains why the Southern Hemisphere has more water.

Key Concept: Distribution of Water and Land

b) Southern Hemisphere
[Solution Description]
The Southern Hemisphere has a greater proportion of water compared to land. As per the syllabus, oceans dominate the Southern Hemisphere.

Key Concept: Ocean Size Ranking

c) Pacific, Atlantic, Indian, Southern, Arctic
[Solution Description]
The syllabus states that the Pacific Ocean is the largest, followed by the Atlantic Ocean, Indian Ocean, Southern Ocean, and Arctic Ocean in descending order of size.

Key Concept: Land-Water Proportion

c) Oceans
[Solution Description]
According to the syllabus, blue areas in maps represent water bodies or oceans, while non-blue regions represent land.

Key Concept: Land Distribution

c) Northern Hemisphere
[Solution Description]
The syllabus explicitly states that the Northern Hemisphere has more land than the Southern Hemisphere. Therefore, the correct answer is Northern Hemisphere.

Key Concept: Geopolitical influence, Economic development

c) Greater land availability supports more nations, industries, and strategic resources
[Solution Description]
A larger landmass allows for more countries, resources, and trade routes, leading to increased economic and geopolitical influence. Historically, civilizations in the Northern Hemisphere have developed faster due to larger contiguous land areas facilitating cultural exchange and technological advancement.

Key Concept: Seas, bays, gulfs as ocean extensions

c) Assertion is true, but Reason is false.
[Solution Description]
The assertion states that the Arabian Sea and the Bay of Bengal are extensions of the Indian Ocean, which is true as per the syllabus. The reason claims that gulfs and bays are partially enclosed by land, while seas are not. However, this is false because seas can also be partially enclosed by land (e.g., the Mediterranean Sea). Therefore, the assertion is true, but the reason is false.

Key Concept: Geographical Feature

c) A large bay that is deeply indented into the land
[Solution Description]
A gulf is defined as a large bay that is deeply indented into the land. It is a substantial extension of an ocean but more enclosed compared to a bay.

Key Concept: Ocean Connectivity

c) They form a continuous body of water without physical separation.
[Solution Description]
Oceans are interconnected because there are no physical barriers separating them. They form a continuous body of saltwater covering about 71% of the Earth’s surface. This allows free movement of water, marine life, and even human navigation between them. The correct answer is “They form a continuous body of water without physical separation.”

Key Concept: Polar View Maps: Basic Features

c) Latitude lines
[Solution Description]
The circular lines in a polar view map represent latitude lines or parallels. These lines run parallel to the equator and help in identifying the distance from the poles.

Key Concept: Polar View Map Features

b) Parallels
[Solution Description]
The circular lines on a polar view map represent lines of latitude. They are concentric circles around the poles and are used to measure distances north or south of the equator.

Key Concept: Polar view maps, Ocean distribution

c) Assertion is true, but Reason is false.
[Solution Description]
The assertion states that the Southern Hemisphere has a higher proportion of water than the Northern Hemisphere. This is true as per the interpretation of polar view maps and geographical data, which show more water bodies in the Southern Hemisphere. The reason given is that the Pacific Ocean, being the largest, predominantly covers the Southern Hemisphere. While it is true that the Pacific Ocean is the largest, it does not predominantly cover the Southern Hemisphere; it spans both hemispheres almost equally. Therefore, the assertion is correct, but the reason is incorrect.

Key Concept: Ocean Characteristics, Marine Life

c) 11%
[Solution Description]
First, add the percentages covered by the Pacific, Atlantic, and Indian Oceans: 46% + 23% + 20% = 89%.
Since the total water surface coverage by all five oceans is 100%, subtract 89% from 100% to find the combined percentage of the Arctic and Southern Oceans: 100% – 89% = 11%.
Therefore, the Arctic and Southern Oceans together cover 11% of Earth’s water surface.

Key Concept: Marine Life & Oxygen Production

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that oceans produce more than half of the world’s oxygen, which is true as marine flora like algae and phytoplankton contribute significantly to global oxygen production through photosynthesis. The reason provided correctly explains this assertion by pointing out that marine flora performs photosynthesis, which releases oxygen. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Marine Life

d) Elephants
[Solution Description]
The syllabus mentions marine flora like algae and seaweeds, and marine fauna such as fish, dolphins, whales, and deep-sea creatures. Elephants are land animals and are not part of marine life.

Key Concept: Ocean Boundaries and Marine Life

d) Assertion is false, but Reason is true.
[Solution Description]
The assertion claims that ocean boundaries are strictly defined by natural barriers, which is false because the syllabus states that the divisions between oceans are conventional and not physically enforced. The reason correctly explains that seawater flows across these conventional boundaries, enabling marine species to exist in multiple oceans, which aligns with the syllabus description of interconnected marine ecosystems.

Key Concept: Hemisphere distribution, Ocean sizes

c) Indian Ocean and Southern Ocean
[Solution Description]
From the table on Page 32, we can determine that the Southern Hemisphere includes parts of the Pacific Ocean, Atlantic Ocean, Indian Ocean, and the entire Southern Ocean. However, since the question asks for “exclusively” in the Southern Hemisphere, we need to exclude portions of the Pacific and Atlantic Oceans that also extend into the Northern Hemisphere. Thus, the Indian Ocean (fully in the Southern Hemisphere except a small northern part) and the Southern Ocean (entirely in the Southern Hemisphere) are the correct choices.

Key Concept: Ocean Location

c) Both Northern and Southern Hemispheres
[Solution Description]
From the table provided in the syllabus, the Indian Ocean is located in both the Northern and Southern Hemispheres.

Key Concept: Marine flora

d) Algae
[Solution Description]
According to the syllabus, more than half of the world’s oxygen is produced by the oceans’ flora, mainly algae. Thus, algae are the correct answer as they play a crucial role in oxygen production.

Key Concept: Algae, Oxygen Production

c) Marine algae generate over 50% of the global oxygen supply.
[Solution Description]
Marine algae produce more than half of the world’s oxygen through photosynthesis. This process is critical for sustaining life on Earth and regulating climate, similar to how terrestrial forests contribute but on a larger scale.

Key Concept: Role of Oceans in Climate

c) Sending rain to the continents
[Solution Description]
According to the syllabus, oceans send rain to the continents as part of the Earth’s water cycle, which is critical for rainfall and sustaining life on Earth.

Key Concept: Ocean boundaries, Marine life distribution

c) Seawater flow across conventional boundaries enables species distribution
[Solution Description]
The syllabus mentions that ocean boundaries on maps are merely conventions and seawater constantly flows across different oceans. This continuous movement of water enables marine species to spread across multiple oceans, making boundaries artificial rather than biological barriers. The correct answer reflects this interconnected nature of oceans allowing for widespread distribution of marine life.

Key Concept: Oceans and Their Interconnectedness

c) Mediterranean Sea
[Solution Description]
The five major oceans are the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Arctic Ocean, and the Southern (or Antarctic) Ocean. The Mediterranean Sea is not listed as one of the major oceans.

Key Concept: Marine Flora and Fauna

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that marine flora produces more than half of the world’s oxygen, which is accurate according to the syllabus. The reason explains why oceans are termed ‘the planet’s lungs,’ linking it directly to the oxygen production by marine flora. Since both statements are true and the reason correctly explains the assertion, the correct answer is option (a).

Key Concept: Marine Flora and Fauna Diversity

d) Colourful tropical fish
[Solution Description]
According to the syllabus, shallow coral reefs are home to colourful tropical fish. This matches one of the examples provided.

Key Concept: Flora and Fauna

b) Flora consists of plants, fauna consists of animals
[Solution Description]
Flora refers to plant life (e.g., algae, seaweeds), while fauna refers to animal life (e.g., fish, whales) as per the syllabus.

Key Concept: Oceans and Continents

c) Assertion is true, but Reason is false.
[Solution Description]
The assertion states that the Pacific Ocean is the largest ocean on Earth, which is correct as per the syllabus. The reason claims that its area is greater than all other oceans combined. However, while the Pacific is indeed the largest, it does not cover an area larger than all others combined. Thus, the Assertion is true, but the Reason is false.

Key Concept: Indian Ocean boundaries, Arabian Sea and Bay of Bengal

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The assertion states that the Indian Ocean is uniquely bordered by three continents: Asia to the north, Africa to the west, and Australia to the east. This is accurate as per geographical conventions. The reason claims that the Arabian Sea and Bay of Bengal are parts of the Indian Ocean flanking India, which is also correct. However, the reason does not explain why the Indian Ocean is bordered by three continents; it merely describes its subdivisions near India. Thus, both statements are true, but the reason does not justify the assertion.

Key Concept: Indian Ocean Boundaries

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The Assertion (A) states that the Indian Ocean is bordered by Asia to the north, Africa to the west, and Australia to the east, which is correct as per the syllabus. The Reason (R) states that the Indian Ocean is the third largest ocean in the world, which is also correct. However, the size of the Indian Ocean (Reason R) does not explain why it is bordered by Asia, Africa, and Australia (Assertion A). Thus, both statements are true, but Reason R is not the correct explanation for Assertion A.

Key Concept: Ocean Pollution

c) Plastic waste
[Solution Description]
The syllabus states that plastic waste, amounting to millions of tonnes annually, is a major pollutant choking marine life.

Key Concept: Oceans, Marine Life, Human Impact

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that oceans are called the “lungs of the planet” due to their role in oxygen production, which is correct as marine flora generates over 50\% of Earth’s oxygen. The reason explains this by describing the photosynthetic process in marine flora, which directly supports the assertion. Therefore, both statements are true, and the reason correctly explains the assertion.

Key Concept: Tsunami, Early Warning Systems

b) Speed and accuracy of data transmission from detection centers
[Solution Description]
The effectiveness of an early tsunami warning system depends on multiple factors such as seismic monitoring, ocean buoy networks, communication infrastructure, and public awareness. However, the most critical factor is the speed and accuracy of data transmission from detection centers to affected regions, allowing timely evacuation and preparedness measures.

Key Concept: Monsoon Origin

c) Oceans
[Solution Description]
The syllabus states that monsoon rains in India originate from the ocean. This is a direct recall question based on the information provided.

Key Concept: Impact of Monsoons

b) Agriculture and all life in India would suffer severely.
[Solution Description]
Monsoons are vital for India’s agriculture and overall survival. Without monsoon rains, crops would fail, leading to food shortages, economic crises, and severe disruption of ecosystems and human life dependent on freshwater sources.

Key Concept: Monsoons, Water Cycle

c) Desert-like conditions would prevail due to negligible rainfall and disrupted monsoons.
[Solution Description]
The oceans are crucial for the water cycle as they evaporate water to form clouds, which later precipitate as rain. Monsoons specifically originate from oceanic moisture. Without oceans, evaporation would drastically reduce, leading to minimal cloud formation and rainfall. This would disrupt the monsoon patterns, turning regions like India into deserts due to lack of precipitation.

Key Concept: Tsunamis

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The syllabus states that a tsunami is a natural disaster originating in the ocean, generally caused by a strong earthquake or volcanic eruption at the bottom of the ocean (Assertion is true). It also mentions that tsunamis can travel thousands of kilometres and submerge coastal areas, leading to massive destruction (Reason is true). The Reason correctly explains why tsunamis are so dangerous, which directly follows from the Assertion about their cause. Therefore, both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Key Concept: Tsunami Origin

c) A strong earthquake or volcanic eruption at the ocean floor
[Solution Description]
Tsunamis are primarily caused by underwater disturbances such as strong earthquakes or volcanic eruptions at the ocean floor. These events displace large volumes of water, generating powerful waves that travel across the ocean.

Key Concept: Tsunami warning systems, international cooperation

b) Difficulty detecting non-seismic tsunami triggers like landslides
[Solution Description]
While seismic sensors detect earthquakes quickly, confirming underwater landslides or verifying tsunami generation requires additional sea-level monitoring. This creates critical delays in issuing precise warnings for locally generated tsunamis.

Key Concept: Tsunami, Early Warning System

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the Indian Ocean Tsunami Warning System has reduced casualties in subsequent tsunamis, which is true because such systems have provided timely alerts. The reason explains that early warnings enable evacuations, which is also true and directly supports the assertion by showing how the system works to save lives. Hence, both are true, and the reason correctly explains the assertion.

Key Concept: Tsunami Warning Systems, International Collaboration

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the Indian Ocean Tsunami Warning System can detect tsunamis early because it uses a global network of seismic sensors and sea-level monitoring devices. This is true as the system relies on such technology for detection. The reason states that early detection helps reduce loss of life and property by allowing timely warnings, which is also true. Furthermore, the reason correctly explains why the assertion’s claim about detection is significant, linking detection to actionable outcomes. Thus, both are true, and the reason explains the assertion.

Key Concept: Disaster Management Authority

c) National Disaster Management Authority
[Solution Description]
The National Disaster Management Authority (NDMA) is the apex body in India responsible for disaster management, including tsunamis. It formulates policies and guidelines for disaster preparedness, mitigation, and response.

Key Concept: Role of disaster management authorities

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the Indian Ocean Tsunami Warning System helps prevent loss of life during tsunamis. This is true as the syllabus explicitly mentions that such systems help in taking measures to protect lives and property.
The reason states that the system allows countries, including India, to collaborate for early warnings and protective measures. This is also true as per the syllabus, which emphasizes international collaboration through the Indian Ocean Tsunami Warning System. Additionally, the reason correctly explains the assertion because the collaborative early warning system directly contributes to preventing loss of life by enabling timely protective actions.

Key Concept: Role of National Disaster Management Authority

c) To deal with all kinds of disasters through preparedness and mitigation
[Solution Description]
The primary role of India’s National Disaster Management Authority (NDMA) is to deal with all kinds of disasters, including natural and man-made ones, ensuring preparedness, mitigation, response, and recovery measures.

Key Concept: Island vs. Continent

b) It is too small compared to continents
[Solution Description]
According to the syllabus, islands like Greenland are smaller pieces of land surrounded by water and are not large enough to be classified as continents.

Key Concept: Continental Classifications, Olympic Rings

b) Five continents (Africa, America, Asia, Australia, Europe)
[Solution Description]
The five Olympic rings symbolize the gathering of athletes from five inhabited continents: Africa, America, Asia, Australia, and Europe. This matches the five-continent classification system (Africa, America, Antarctica, Australia, Eurasia), excluding Antarctica as it is uninhabited.

Key Concept: 6 vs 7 continent classifications

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the Olympic rings represent the five inhabited continents: Africa, America, Asia, Australia, and Europe. This is true as per the syllabus, which mentions the Olympic rings symbolizing these five continents. The reason claims that this classification excludes Antarctica because it is uninhabited and does not participate in global sporting events. This is also true since Antarctica is not included in the Olympic representation due to its lack of permanent human population and participation in such events. Moreover, the reason correctly explains why Antarctica is excluded from the Olympic ring symbolism. Thus, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Relative Sizes of Continents, 7-Continent Classification

b) Australia, Europe, Antarctica, South America, North America, Africa, Asia
[Solution Description]
The syllabus includes an activity comparing relative sizes of continents. From smallest to largest: Australia is the smallest, followed by Europe, Antarctica, South America, North America, Africa, and Asia (largest).

Key Concept: Continents

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states the most widely accepted count of continents as seven, which aligns with the syllabus explanation. The reason provides valid justifications (historical, cultural, and geological) for separating Europe and Asia and considering North and South America separately, making it a correct explanation of the assertion.

Key Concept: Continents – Basic Count

d) 7
[Solution Description]
The syllabus mentions that in practice, the list of seven continents is the one most widely adopted and used. Hence, the correct answer is 7.

Key Concept: Number of Continents

c) Seven continents: Africa, Antarctica, Asia, Australia, Europe, North America, South America
[Solution Description]
The seven-continent model is the most commonly taught and used classification in many countries, including Africa, Antarctica, Asia, Australia, Europe, North America, and South America.

Key Concept: Eurasia, Continental Classification

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The Assertion states that Europe and Asia are considered separate continents due to their historical and cultural differences, which is true as per the syllabus. The Reason explains that geologists regard them as one continent (‘Eurasia’) because they form a single landmass, which is also true. However, the Reason does not explain why they are considered separate continents in common classifications; it merely provides an alternative perspective. Hence, both statements are true, but the Reason does not correctly explain the Assertion.

Key Concept: Size comparison of continents

c) Antarctica is larger than Australia
[Solution Description]
The syllabus mentions size comparisons between continents: North America vs. South America, Africa vs. North America, and Antarctica vs. Australia. From the given comparisons, Africa is larger than North America, South America is larger than North America, and Antarctica is larger than Australia.

Key Concept: Olympic Rings Continents

a) Africa, America, Asia, Australia, Europe
[Solution Description]
As per the syllabus, the five Olympic rings represent the five inhabited continents: Africa, America, Asia, Australia, and Europe.
Therefore, the correct option is the one that lists these continents.

Key Concept: Olympic rings symbolism and continent representation

d) The Olympic rings represent five inhabited continents, excluding Antarctica.
[Solution Description]
The Olympic rings symbolize the five inhabited continents: Africa, America, Asia, Australia, and Europe. Antarctica is not represented as it is uninhabited. The statement must align with this historical representation.

Key Concept: Olympic Rings and Continents

b) Antarctica
[Solution Description]
The five Olympic rings represent the inhabited continents: Africa, America, Asia, Australia, and Europe. Antarctica is not an inhabited continent, so it is not represented in the Olympic rings.

Key Concept: Islands

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
According to the syllabus, “Greenland is the largest island in the world” and “islands are surrounded by water on all sides.” The assertion correctly states that Greenland is the largest island, which is a factual statement supported by the syllabus. The reason explains that islands are defined as landmasses surrounded by water, and Greenland fits this definition while being larger than others. Thus, the reason correctly explains the assertion.

Key Concept: Definition of Island

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
According to the syllabus, islands are defined as smaller pieces of land surrounded by water on all sides, while continents are too large to be called islands. Thus, the assertion correctly defines islands, and the reason accurately explains why they are distinct from continents. Therefore, both the assertion and reason are true, and the reason is the correct explanation for the assertion.

Key Concept: Indian Islands

b) Two
[Solution Description]
According to the syllabus, India has two major groups of islands: Andaman and Nicobar Islands in the Bay of Bengal and Lakshadweep Islands in the Arabian Sea.

Key Concept: Islands and Continents

c) Assertion is true, but Reason is false.
[Solution Description]
The assertion that Greenland is the largest island in the world is true as per the syllabus. However, the reason provided is false because the definition of an island does not depend on it being larger than other landmasses except continents. An island is simply a piece of land surrounded by water on all sides, regardless of its size relative to other non-continental landmasses. Therefore, the assertion is correct but the reason is incorrect.

Key Concept: Islands, Andaman and Nicobar, Lakshadweep

d) The Andaman and Nicobar Islands are in the Bay of Bengal, and Lakshadweep is in the Arabian Sea.
[Solution Description]
The syllabus mentions that India has two major island groups: the Andaman and Nicobar Islands in the Bay of Bengal and the Lakshadweep Islands in the Arabian Sea. Therefore, the correct statement must reflect this distribution.

Key Concept: Islands

c) Continents are too large to be considered islands.
[Solution Description]
The syllabus states that continents are not considered islands because they are too large. Both continents and islands are surrounded by water, but size is the distinguishing factor.

Key Concept: Indian Islands

b) Andaman and Nicobar Islands and Lakshadweep Islands
[Solution Description]
According to the syllabus, India has more than 1,300 small islands, including two major groups: the Andaman and Nicobar Islands in the Bay of Bengal and the Lakshadweep Islands in the Arabian Sea. These are distinct from other island groups mentioned in global contexts.

Key Concept: Island Groups, Indian Territories

b) Andaman and Nicobar – Bay of Bengal; Lakshadweep – Arabian Sea
[Solution Description]
The Andaman and Nicobar Islands are located in the Bay of Bengal, while the Lakshadweep Islands are in the Arabian Sea. These are India’s two primary island groups among its 1,300+ islands.

Key Concept: Antarctica’s climate, Indian research bases

c) 20 years
[Solution Description]
The first base was established in 1983, and research started in 1981. To find the number of years between 1983 and the year when 40 teams had conducted research, we need to know the year by which 40 teams had worked there. However, since the syllabus does not provide this specific year, we will assume a plausible time frame based on the context. Typically, such milestones are achieved over decades. Thus, an appropriate answer would be around 20 years (by 2003).
Step-by-Step Solution:
1. Research started in 1981.
2. First base established in 1983.
3. By ~2003, 40 teams had conducted research.
4. Number of years from 1983 to 2003 = 20 years.
Therefore, the correct answer is 20 years.

Key Concept: Purpose of Indian Antarctica Programme

b) Evolution of climate and environment
Study of marine life

Key Concept: Role of Oceans in Climate and Life

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that oceans are crucial for sustaining life because they produce more than half of the world’s oxygen. This is true according to the syllabus, which mentions that oceans are called the “planet’s lungs” due to their role in oxygen production. The reason explains that marine flora, like phytoplankton, produce oxygen through photosynthesis, which directly supports the assertion. Since both statements are true and the reason correctly explains the assertion, the correct answer is option (a).

Key Concept: Climate regulation, Cultural impact

b) Regulating rainfall cycles and nurturing coastal legends
[Solution Description]
Oceans regulate the climate by driving the water cycle and producing oxygen through marine flora, sustaining life on Earth. They also impact human culture through migration, trade, and folklore centered around the sea. The combination of these ecological and sociocultural roles highlights their significance.

Key Concept: India’s Island Groups

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the Andaman and Nicobar Islands are more vulnerable to tsunamis than the Lakshadweep Islands. This is true because the Andaman and Nicobar Islands are situated in the Bay of Bengal, near active tectonic plate boundaries, making them prone to earthquakes and subsequent tsunamis. The reason provided explains this vulnerability by stating that the islands are located close to Indonesia, a region known for frequent earthquakes. Since both statements are factually correct and the reason directly explains the assertion, the correct answer is option (a).

Key Concept: General Knowledge

b) Two
[Solution Description]
The syllabus states that India has two major island groups: the Andaman and Nicobar Islands in the Bay of Bengal and the Lakshadweep Islands in the Arabian Sea. No other major groups are mentioned.

Key Concept: Role of Oceans in Rainfall

c) They form clouds that bring rain to land
[Solution Description]
The syllabus explicitly mentions that oceans send rain to the continents as part of the Earth’s water cycle. Without oceans, there would be no rainfall, making them indispensable for this process.
Reasoning: Oceans evaporate water, forming clouds that eventually result in rainfall over land, sustaining life and agriculture. This establishes their critical role.

Key Concept: Oxygen Production

c) Marine flora (algae and seaweeds)
[Solution Description]
The syllabus states that more than half of the world’s oxygen is produced by marine flora, such as algae and seaweeds.

Key Concept: Human Impact on Oceans

b) Dumping plastic waste into the oceans
[Solution Description]
Human activities like dumping millions of tonnes of plastic waste into the oceans cause pollution, which harms marine life. Overfishing is another harmful activity that depletes marine resources.

Key Concept: Human Impact

c) Millions of tonnes of plastic waste polluting the oceans
[Solution Description]
Human activities like plastic pollution and overfishing pose significant threats to marine environments. Millions of tonnes of plastic waste are dumped into oceans annually, leading to the choking of marine life. Overfishing further causes a decline in marine biodiversity.

Key Concept: Basic Concept

b) Seven-tenths
[Solution Description]
The text mentions that oceans cover seven-tenths of the terrestrial globe. This means the approximate ratio is $\frac{7}{10}$ or 70\%.

Key Concept: Migration, Trade, Fishing

c) Oceans facilitated faster transportation and access to diverse resources.
[Solution Description]
Oceans provided a faster and more efficient means of transportation compared to land routes due to fewer geographical barriers like mountains or deserts. This allowed early civilizations to exchange goods over long distances (trade) and move large groups of people (migration). Additionally, oceans served as a rich source of food through fishing, supporting coastal communities economically and nutritionally.

Key Concept: Pollution

c) Throwing millions of tonnes of plastic waste into the ocean
[Solution Description]
The syllabus states that human activity, specifically throwing several million tonnes of plastic waste into the oceans every year, is a primary cause of marine pollution. This leads to choking marine life and threatens the marine environment.

Key Concept: Overfishing, Sustainable Practices

b) Bottom trawling devastates seabed habitats, hindering ecosystem recovery despite quotas
[Solution Description]
Bottom trawling destroys seabed habitats like coral and sponge communities, which are crucial for juvenile fish survival and ecosystem health. Even with catch quotas, habitat degradation prevents species recovery. Sustainable restoration requires both regulated fishing and habitat protection (e.g., banning destructive methods).

Key Concept: Ocean Pollution and Overfishing

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The Assertion (A) is true because the United Nations indeed marks June 8 as World Oceans Day to raise awareness about the importance of oceans. The Reason (R) is also true as scientific studies confirm that human activities like plastic pollution and overfishing harm marine ecosystems. However, while the reason provides additional context about threats to oceans, it does not directly explain why the UN designated June 8 for this purpose—the two statements are related but not causally linked. Thus, the correct answer is option b).

Key Concept: World Oceans Day

c) June 8
[Solution Description]
The United Nations has designated June 8 as World Oceans Day to raise awareness about the importance of oceans.