JAMB UTME - Geography - 2024

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Rocks that are formed from the cooling and solidification of molten magma are called igneous rocks.

To put it simply, when rocks melt deep beneath the Earth's surface because of the high temperatures, they turn into a liquid called magma. This magma can sometimes rise to the surface in the form of lava. Once either the magma or lava cools down and becomes solid, it forms a new type of rock known as igneous rock.

These rocks can be formed inside the Earth when the magma cools slowly, creating large crystals, or on the Earth's surface, when the lava cools quickly, often resulting in smaller crystals. The word "igneous" comes from a Latin word meaning "fire," which appropriately describes how these rocks form from the hot, molten magma.

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The movement of population from rural areas to cities, commonly known as urbanization, is influenced by several factors, particularly economic and social opportunities. In the context of Nigeria, one of the most significant reasons is due to the availability of more job opportunities in the cities. Urban centers often offer a greater variety of employment possibilities compared to rural areas. These opportunities can be in industries, services, or various sectors requiring skilled and unskilled labor.

Economic development tends to be concentrated in cities, attracting individuals seeking better employment prospects and higher income potential. Many people move to urban areas in search of work that they cannot find in their rural hometowns, where agriculture may be the predominant source of livelihood with limited economic diversification.

Moreover, cities in Nigeria typically provide better recreational facilities and services than rural areas. These include access to modern amenities such as shopping centers, cinemas, sports facilities, and cultural events, which contribute to a higher quality of life. This aspect is appealing, particularly to younger generations, creating an added incentive for migration.

The other factors mentioned, such as food scarcity in rural areas, might contribute to migration but are often secondary compared to the employment factor. Many rural areas have agricultural activities, so food scarcity is not the primary reason; instead, it's the lack of economic opportunities that often triggers the movement.

Finally, while it is true that the cost of living in the cities is very high, especially in terms of housing and services, this is not a reason that attracts people to move. In fact, it might be a deterrent. Nonetheless, the potential for better income and lifestyle improvement in cities often outweighs the high cost of living for many migrants.

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Copper is an important raw material in the electrical industry. This is because copper is an excellent conductor of electricity, which means it allows electrical current to flow through it easily with minimal resistance. This property makes copper ideal for use in electrical wiring, motors, transformers, and other electrical components. Additionally, copper is highly durable, resistant to corrosion, and versatile, which further enhances its usefulness in electrical applications. The electrical industry relies heavily on copper to ensure reliable and efficient power transmission.

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The high population density in the Nile Valley is best explained by the presence of rich alluvial soil. The Nile River floods annually, depositing nutrient-rich silt along its banks, which creates fertile land perfect for agriculture. This fertile land supports farming, which is the primary means of livelihood for many people in the region. The availability of fertile soil allows for the cultivation of crops such as wheat, barley, and other foodstuffs, supporting a large population by providing food resources and encouraging human settlement. This agricultural productivity attracts people to settle, leading to a higher population density. It is not primarily due to climate, migration from Europe, or oil fields.

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The longest river in Africa is the Nile River. The Nile River is renowned for its extraordinary length, stretching approximately 6,650 kilometers (about 4,130 miles). This majestic river traverses several countries in northeastern Africa, including Uganda, Sudan, and primarily Egypt. Its extensive reach makes it the longest river not only in Africa but also in the world, although there is some debate with the Amazon River.

The Nile plays a crucial role in the cultures and economies of the nations it flows through. In ancient Egypt, for instance, it was vital for agriculture, enabling civilizations to thrive by providing a reliable source of water and fertile land for farming. Today, the Nile continues to be a lifeline for millions of people, supporting agriculture, transport, and providing drinking water.

In contrast, the other rivers mentioned, such as the Zambezi, Senegal, and Congo, though significant in their own right, are shorter and do not match the extraordinary length of the Nile River.

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Let's understand the term **headward erosion**. **Headward erosion** refers to the process where a river or stream erodes its source region, causing the stream's origin to move backward away from the direction of water flow. This process can have several impacts and can lead to the formation of certain landforms.

Among the options provided, **headward erosion** is most commonly associated with the formation of **river capture**. When **headward erosion** continues over time, it can cause one river to extend its course and intersect with a neighboring river, capturing its flow. This event is known as **river capture** or **stream piracy**. Essentially, the rapid erosion at the river's source enables it to cut through the drainage divide and capture the headwaters of another river.

Let's briefly see why the other options are less relevant to **headward erosion**:

• **Potholes** are typically formed on the riverbed as a result of mechanical weathering and the swirling movement of water and debris, rather than headward erosion.
• **Oxbow lakes** form when a meander from a river is cut off, creating a free-standing body of water, which is more a result of lateral erosion rather than headward erosion.
• **Alluvial cones** or **alluvial fans** form where a river or stream spreads out sediment as it exits a mountainous area onto a flatter plain. This is not directly caused by **headward erosion**, but rather sediment deposition.

Therefore, the process of **headward erosion** most directly leads to the formation of **river capture**.

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Quartzite, schist, and marble are all examples of metamorphic rocks.

Here's why:

• Metamorphic Rocks: These are rocks that have undergone a transformation due to intense heat and pressure. This process, called metamorphism, alters their original form or mineral composition without melting them.
• Quartzite: This forms from sandstone, a sedimentary rock, that has been exposed to heat and pressure, resulting in a very hard, durable rock.
• Schist: This rock is typically formed from shale, another sedimentary rock, or sometimes from basalt, an igneous rock. It has a shiny appearance due to the presence of mica minerals.
• Marble: This is formed from limestone, a sedimentary rock that undergoes recrystallization under high heat and pressure, resulting in a rock that is often used in sculpture and architecture.

Sedimentary Rocks are formed from the accumulation of sediments, while Igneous Rocks are formed from the cooling and solidification of magma or lava. Volcanic rocks are a subset of igneous rocks that specifically form from lava at the earth's surface. Thus, quartzite, schist, and marble do not fall under these categories.

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The route that is not a sea route is the one involving London, Moscow, and Baghdad.

Here's the explanation:

• The other listed routes such as New York-London-Rotterdam, London-Capetown-Melbourne, and Sydney-Suez-London primarily involve locations that are major port cities or are connected by significant sea passages, allowing ships to travel via water routes.
• On the other hand, Moscow is a landlocked city in Russia, and although it has some rivers, it does not have direct access to the sea. Moreover, the path from London to Moscow to Baghdad mostly travels overland, across Europe and parts of Asia, which are areas not typically traversed by ships in any well-known sea route.

This is why the route from London, Moscow, and Baghdad is not a sea route.

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To determine the longitude of place X, we need to understand the relationship between time and longitude. The Earth is divided into 360 degrees of longitude, and it completes one full rotation (360 degrees) in 24 hours. Therefore, for every hour, the Earth rotates 15 degrees of longitude.

The given information is this:

• Greenwich Mean Time (GMT) is 5:00 a.m.
• Local time at place X is 12:00 noon.

The difference in time between GMT and the local time at place X is 7 hours (from 5:00 a.m. to 12:00 noon).

Calculation:

• For each hour, there is a 15-degree difference in longitude.
• Therefore, a 7-hour difference corresponds to 7 hours × 15 degrees/hour = 105 degrees.

Now, we need to determine whether place X is east or west of the Prime Meridian (0° longitude, the reference line for GMT).

- Since the local time at place X is ahead of GMT (12:00 noon compared to 5:00 a.m.), it means X is east of the Prime Meridian.

Thus, place X is located on 105°E.

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The system of cultivation of tropical commercial crops estates is known as plantation agriculture.

Plantation agriculture is a type of farming where a single crop, often a cash crop, is grown on a large area of land. This method is commonly seen in tropical areas where conditions favor the growth of certain commercial crops like tea, coffee, rubber, cocoa, and palm oil.

The defining characteristics of plantation agriculture include:

• Large Scale Production: Crops are grown on expansive estates, which enable significant quantities to be produced.
• Monoculture: Typically, only one type of crop is cultivated for commercial purposes at a time, making it a form of monoculture.
• Capital-Intensive: It often requires heavy investment in machinery, infrastructure, and labor.
• Export-Oriented: The crops grown are usually intended for international trade, contributing to the economy of the region.
• Scientific Techniques: Utilizes advanced agricultural technologies and scientific methods to maximize yield and productivity.

This system significantly contributes to the economies of tropical regions by generating foreign exchange and providing employment opportunities.

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The innermost section of the Earth is the core. The Earth is composed of several layers, starting from the surface and moving inward. These layers, from the outside to the inside, are the crust, mantle, outer core, and inner core.

1. Crust: This is the outermost layer of the Earth. It is very thin compared to the other layers and is where we live. The crust is made up of solid rocks and minerals.

2. Mantle: Located beneath the crust, the mantle is composed of semi-solid rock that flows slowly. It is the largest layer of the Earth by volume.

3. Core: The core itself is divided into two parts: the outer core and the inner core. The outer core is made of molten, liquid metal, while the inner core is made of solid metal, primarily iron and nickel. The core is the hottest section of the Earth, with extremely high temperatures and pressures. It is situated at the center of the Earth and provides heat that helps power the movement of tectonic plates and causes volcanic activity.

Therefore, when we refer to the innermost section of the Earth, we are specifically talking about the core, and more accurately, the inner core.

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One of the major problems impacting the effective utilization of human resources in West Africa is unemployment.

Unemployment is a significant issue because it leads to several challenges that adversely affect both individuals and the economy at large. When people, especially those who are capable and willing to work, do not have jobs, it results in a waste of potential human resources. Let's break down a few reasons why unemployment is such a pressing problem:

• Economic Impact: High unemployment rates mean that a large portion of the population is not contributing to the economic growth of the country. This diminishes the overall productivity and can lead to a lower Gross Domestic Product (GDP).
• Poverty: Unemployment often results in income instability, which can push individuals and families into poverty. This lack of income makes it challenging to meet basic needs such as food, education, and healthcare.
• Social Challenges: High levels of unemployment can lead to increased crime rates and social unrest, as people without jobs may resort to illegal activities to support themselves.
• Brain Drain: Persistently high unemployment can lead to emigration, where skilled individuals move to other countries in search of better opportunities. This exacerbates the issue as it creates a loss of talented individuals who could have contributed to local development.
• Skill Deterioration: When people remain unemployed for extended periods, their professional skills may deteriorate, making it even harder for them to find employment in the future.

Addressing unemployment requires collaborative efforts involving government policies, education systems, and private sector initiatives to create more job opportunities and develop skills that match the demands of the labor market. Therefore, unemployment remains a critical concern in achieving optimal utilization of human resources in West Africa.

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The world's busiest shipping routes are found on the Atlantic Ocean. This ocean plays a crucial role in global trade and transportation due to several factors:

• Location: The Atlantic Ocean is strategically located between the continents of North America, Europe, and Africa. This positioning makes it an important corridor for trade between the densely populated and economically developed regions, including the United States, Canada, Western Europe, and parts of Africa.
• Economic Activity: Countries bordering the Atlantic Ocean, such as the United States, European countries, and Brazil, are some of the world's largest economies. As such, there is a high volume of goods being exchanged across the Atlantic Ocean, contributing to its status as a busy shipping route.
• Major Ports: The Atlantic Ocean hosts several significant ports like Rotterdam, Antwerp, Hamburg, New York, and Shanghai, to name a few. These ports serve as major hubs for commerce, where goods are received, processed, and shipped globally, adding to the traffic on this ocean.
• Historical Significance: Historically, the Atlantic Ocean has been a primary route for exploration and trade since the Age of Discovery. This long-standing use has established robust shipping routes that continue to be essential for international trade.

While other oceans like the Pacific and Indian Oceans are also important for global trade, the Atlantic Ocean remains particularly significant due to its connectivity and the economic powerhouses it links. The Antarctic Circle is not a major route due to its harsh environmental conditions and minimal human inhabitation, which reduces commercial sea traffic in that region.

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On June 21st, when the sun is overhead at the Tropic of Cancer, places in the Northern Hemisphere experience a phenomenon often referred to as the **Summer Solstice**. This day marks the point when the Northern Hemisphere is tilted closest to the Sun. As a result, it receives the most direct sunlight compared to any other day of the year.

During this time, the day is significantly longer than the night. This is because the Sun travels a longer path through the sky, remaining visible for a larger portion of the 24-hour day. Therefore, areas in the Northern Hemisphere experience a **longer day and shorter night**.

This occurrence is most noticeable the further north you go, with some regions near the Arctic Circle experiencing the phenomenon known as the "Midnight Sun," where the sun is visible at midnight.

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When a ship appears over the distant horizon, the mast is seen before the hull. This phenomenon can be explained by considering the shape of the Earth and how light travels.

The Earth is a large sphere, and because of its curvature, objects that are farther away become obscured by the Earth's surface as they move over the horizon. The upper parts of an object, such as the mast of a ship, are further away from the Earth's surface compared to the lower parts, like the hull. As a result, the top parts become visible first as an object like a ship comes over the horizon.

Therefore, due to the curvature of the Earth, the mast, being higher and more elevated, comes into view before the hull as the ship approaches from a distance.

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The major source of power for most terrestrial ecosystems is solar energy.

Let me explain why:

Solar energy is the energy that comes from the sun. It is critical for life on Earth as it powers the process of photosynthesis, which is used by plants, algae, and some bacteria to convert light energy into chemical energy. During photosynthesis, these organisms take in carbon dioxide from the air and water from the soil, and with the help of sunlight, they produce glucose and oxygen. This process provides the necessary energy and organic material to support life.

Here is why it is important:

• Primary Producers: Solar energy fuels the primary producers (mainly plants) that form the base of the food chain. They use sunlight to create food that herbivores eat, and these herbivores are then consumed by carnivores. Without the energy provided by the sun, this foundational level of the food web would not exist, and all life forms that depend on plants, either directly or indirectly, would not survive.
• Energy Transfer: The energy captured by plants is transferred through various trophic levels as different organisms consume one another. Each level receives energy that originated from the sun, making solar energy the primary driving force of energy flow in ecosystems.
• Climate Regulation: Sunlight helps regulate Earth's climate and atmospheric conditions, influencing temperature and weather patterns. These conditions are necessary for the survival of various ecosystems and their inhabitants.

In comparison, other energy sources like geothermal energy, nuclear power, and hydroelectric power play relatively minor roles in terrestrial ecosystems. These energies are not as directly involved in powering the basic life-sustaining processes as solar energy is. Therefore, it is clear that solar energy is the predominant power source for life on land.

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Mechanical weathering is the process of breaking down rocks into smaller pieces without changing their chemical composition. There are several causes of mechanical weathering, but not all processes that affect rocks are related to mechanical weathering.

The options listed include:

Temperature changes: This is a cause of mechanical weathering. When rocks are exposed to fluctuating temperatures, they expand when it's hot and contract when it's cold. Over time, these repeated expansions and contractions can cause the rocks to crack and break apart.

Frost action: Also known as freeze-thaw weathering, this is another form of mechanical weathering. Water can seep into cracks in the rocks, and as temperatures drop, the water freezes and expands. This expansion exerts pressure on the rock, gradually breaking it apart.

Alternate wetting and drying: This causes mechanical weathering by changing the volume of clay minerals found in some rocks. When these rocks get wet, the clay swells, and when dry, it contracts. This constant expansion and contraction lead to mechanical breakdown.

Rain action: This is not primarily a cause of mechanical weathering. While rain can contribute to weathering processes, such as chemical weathering where it reacts with minerals in rocks to form new compounds, its primary role in mechanical weathering is minimal compared to other factors.

Therefore, among the options provided, rain action is the one that is not a direct cause of mechanical weathering.

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The term over-population is best defined as the situation where the population exceeds available resources. This means that the number of people in an area is greater than the resources available to sustain them, such as food, water, shelter, and health care. It can lead to various problems including poverty, environmental degradation, and a strain on infrastructure. Over-population occurs when the existing resources cannot meet the needs of the people, resulting in hardship and reduced quality of life.

In contrast, having a birth rate equal to the death rate implies a stable population over time, not necessarily over-population. Increasing birth rate and decreasing infant mortality can contribute to population growth, but they do not solely define over-population. Finally, high population density refers to a large number of people living in a small area, which could lead to over-population if resources are insufficient, but high density alone does not equate to over-population.

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The angular distance of a point on the Earth's surface measured in degrees from the centre of the Earth east or west of the Greenwich Meridian is known as longitude.

Let's break this down to make it simple:

Longitude lines are imaginary lines that run from the North Pole to the South Pole. The most important line is the Greenwich Meridian, also called the Prime Meridian, which is the reference point for measuring longitude. It is designated as zero degrees (0°) longitude. When you measure how far east or west a point is from the Prime Meridian, you are measuring the longitude.

This is different from latitude, which measures the distance north or south of the Equator. Longitude lines meet at the poles, whereas latitude lines are parallel to each other.

Overall, longitude helps us determine the precise location of a place on Earth by specifying how far east or west it is from the Prime Meridian.

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A great advantage of Basin irrigation is that water is not wasted, as the basin helps to trap and conserve water.

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The development of hydro-electric power in Nigeria is least affected by the availability of suitable sites for dams. While suitable sites are necessary for building dams, other factors such as a regular supply of water and high mountains are more critical for hydro-electric power development.

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The environmental hazard that is due primarily to human activities is ozone depletion.

The ozone layer is a protective shield in the Earth's stratosphere that absorbs most of the Sun's harmful ultraviolet radiation. The thinning of the ozone layer is mainly caused by the release of man-made chemicals. The most significant contributors to this environmental hazard are chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS) which have been used in refrigeration, air conditioning, foam production, and aerosol propellants. When these chemicals reach the stratosphere, they break down ozone molecules, leading to what is known as the "ozone hole."

In contrast, the other environmental hazards listed—hurricanes, earthquakes, and volcanic eruptions—are natural phenomena. While human activities can influence the severity or impact of these events, such as through climate change exacerbating the intensity of hurricanes or human settlement in earthquake-prone areas, they are not primarily caused by human actions.

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The port described in the statement is an entrepôt. An entrepôt is a type of port or a trading post where goods are imported, stored, and then re-exported. It acts as a key transfer point in international trade, allowing products to be redistributed to neighboring countries. This concept operates on the idea that items arrive in bulk and then are sent out again, perhaps even modified or repackaged, often without the goods being subject to customs duties. In essence, an entrepôt streamlines the movement of goods, facilitating international commerce and boosting trade networks.

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To determine which of the listed items is not an element of climate, we need to understand what elements constitute climate. **Climate** refers to the average weather conditions of a place over a long period, typically 30 years or more. The primary elements that define climate include **temperature**, **precipitation**, **humidity**, **wind**, and **air pressure**. Let's go through the choices given:

Precipitation: This is an important element of climate as it refers to any form of moisture that falls from the atmosphere to the earth's surface, such as rain, snow, or sleet.

Air pressure: This is a crucial element of climate because it influences wind patterns and weather systems such as cyclones and anticyclones.

Altitude: This is not an element of climate; rather, it is a geographic factor that influences climate. As you go higher in altitude, temperatures typically decrease, which can affect the climate of a region, but altitude itself is not a climatic element.

Temperature: This is a fundamental element of climate, affecting the average warmth or coldness of a place over time.

Therefore, **altitude** is not an element of climate, but a factor that can influence the other elements like **temperature** and **precipitation**.

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The Biu Plateau has an average height of over 100 meters above sea level. The Biu Plateau is a region of high ground in northeastern Nigeria

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The ocean that connects Europe and America is the Atlantic Ocean.

Here's a simple explanation: The Atlantic Ocean is a massive body of water that lies between the continents of Europe and Africa to the east and the Americas to the west. This ocean is one of the world's five major oceans and is the second largest after the Pacific Ocean. Historically, the Atlantic Ocean has been significantly important as a route for ships traveling between Europe and the Americas, playing a crucial role in exploration, commerce, and cultural exchanges.

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The term fossil fuel refers to energy sources that come from the remains of ancient plants and animals, buried and subjected to heat and pressure over millions of years. These fuels are primarily composed of carbon and include materials like coal, oil, and natural gas.

Among the options given:

• Gneiss is a type of metamorphic rock formed from other rocks like granite or sedimentary rock through heat and pressure. It is not a fossil fuel.
• Granite is an igneous rock that forms from the cooling and solidification of magma beneath the Earth’s surface. It is not a fossil fuel.
• Lignite is a type of coal, which is a fossil fuel. It is often referred to as brown coal and is used primarily as a fuel for steam-electric power generation.
• Mica is a group of minerals that can split into thin, tough sheets. It is not a fossil fuel.

Therefore, the correct answer is Lignite because it belongs to the category of fossil fuels. Lignite is formed from the remains of plants that lived millions of years ago, which makes it a source of stored energy that can be burned for heat and power.

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There is no such thing as a "mountain of accumulation". The other options - conical mountain, block mountain, and fold mountain - are all types of mountains.

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Nigeria, a country located in West Africa, is situated between the longitudes of 3°E and 15°E. Longitude lines are imaginary vertical lines that run across the Earth's surface from the North Pole to the South Pole. These lines help in determining the east-west position of a particular location on earth. By being positioned between 3°E and 15°E, Nigeria stretches from slightly east of the Prime Meridian, which is 0°, to 15° eastward. This geographical positioning affects several aspects like climate and time zone, making it an important detail in understanding the country's location globally.

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The Economic Community of West African States (ECOWAS) is a regional political and economic union of countries located in West Africa. Its objective is to promote economic integration across the region. The official member states of ECOWAS include countries in West Africa.

Among the options provided:

• Cote d'Ivoire is a member of ECOWAS. It is located in West Africa and actively participates in the community’s activities.
• Burkina Faso is also a member of ECOWAS. Like Cote d'Ivoire, it is found in West Africa and is part of the union.
• Senegal is another member state of ECOWAS, contributing to the regional integration efforts.

Cameroun, however, is not a member of ECOWAS. While it is geographically close to West Africa, it is primarily considered part of Central Africa, and it is a member of the Central African community organization instead.

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To determine which option is not a proof of the Earth's spherical shape, let's examine each one:

Twilight and Dawn: Twilight and dawn occur when the Earth rotates, and the sun is below the horizon. The gradual increase or decrease in light during these times is due to the atmosphere bending or scattering sunlight. While this phenomenon is observed worldwide, it by itself doesn't directly indicate a spherical Earth. Instead, it emphasizes the Earth's rotation, which is consistent with a spherical shape.

Lunar Eclipse: During a lunar eclipse, when the Earth is directly between the sun and the moon, the Earth casts a shadow on the moon. This shadow is observed as a circular shape, which provides direct evidence that the Earth is spherical.

Aerial Photograph: Aerial photographs, when taken from a sufficient altitude, can show the curvature of the Earth. Photographs taken from high altitudes give visual evidence of the Earth's curved surface, supporting the spherical shape.

Sunrise and Sunset: The occurrence of sunrise and sunset happens due to the Earth's rotation on its axis. As the Earth rotates, different parts of the world experience sunlight and darkness. This rotation is consistent with the global experience of a spherical planet.

Conclusion: While all the listed phenomena have some connection to the Earth's rotation and shape, **twilight and dawn** do not directly serve as a proof of the Earth's spherical shape. They are more indicative of the rotational aspect and atmospheric effects rather than the shape itself.

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On June 21st, the sun is overhead at the Tropic of Cancer, marking the Summer Solstice in the Northern Hemisphere. This is the point in the year when the Northern Hemisphere is tilted closest to the sun. As a result, places in the Northern Hemisphere experience their longest day and shortest night. This means that there is more daylight compared to nighttime.

To summarize, on this date, locations in the Northern Hemisphere will experience a longer day and a shorter night. This is due to the tilt of the Earth's axis, which maximizes sunlight exposure to these regions.

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Hong Kong, Java, and Manhattan all share the feature of having a **high population density**. These regions are known for their concentrated population in relatively small areas. Here is a simple explanation for each:

• Hong Kong: As a major financial and cultural center, Hong Kong is known for its skyscrapers and bustling city life, housing a large number of people in a compact space.


• Java: This Indonesian island is one of the most densely populated places in the world, being the political, economic, and cultural hub of Indonesia.


• Manhattan: In New York City, Manhattan is famous for its urban density, with many people living and working in high-rise buildings within a small area, contributing to its status as a significant commercial and cultural center.

In summary, the common feature among these locations is their **high population density**, where large numbers of people reside and engage in various activities within limited geographic spaces.

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The major industrial zones of Nigeria owe their origin mainly to the presence of cash crops. This is because, historically, Nigeria's economy largely depended on agriculture, and the availability of these cash crops provided a foundation for establishing industries. For example, regions where cash crops such as cocoa, palm oil, rubber, and groundnuts were abundantly grown became focal points for industries.


These crops were in high demand both locally and internationally, encouraging the establishment of processing industries to add value before export. This led to the development of infrastructure and contributed to the economic growth of these regions.


Thus, the presence of cash crops has played a significant role in shaping the industrial landscape of Nigeria by attracting investments, creating jobs, and fostering economic development in the respective regions.

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Rain clouds most commonly develop in the troposphere. The troposphere is the lowest layer of Earth's atmosphere and extends from the Earth's surface up to about 8 to 15 kilometers (5 to 9 miles) above sea level, depending on your location.

This layer is where we experience weather, including rain, thunderstorms, and clouds. The reason for this is that the troposphere contains most of the atmosphere's water vapor, which is essential for cloud formation and precipitation.

In this layer, the air becomes cooler as you go higher, which allows the moist air to rise, cool, and condense to form clouds. When these clouds get heavy enough with condensed water droplets, they release the water in the form of rain.

The layers above the troposphere, such as the stratosphere, do not usually have the right conditions for rain cloud formation because they lack sufficient moisture and their temperatures are not typically conducive to the processes needed for cloud formation.

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In the context of settlement types and their sizes, the largest is a megalopolis.

Let me explain this in simple terms:

• **City:** A city is a large and permanent settlement with a significant population and infrastructure. It is larger than a town but smaller than the other types of settlements listed here.
• Agglomeration: This term generally refers to an area where multiple cities or towns are grouped together, sharing infrastructure and services but still remaining as distinct entities. It is more about the process of these settlements growing together.
• Conurbation: A conurbation is a region that consists of a number of cities or towns which have merged together over time through population growth and expansion. They are physically connected but maintain individual identities.


• Megalopolis: A megalopolis is a massive urban region made up of multiple large cities and their surrounding areas, which have expanded to merge into one continuous urban area. It's much larger than a conurbation. One classic example is the Northeastern megalopolis in the USA, which includes cities like Boston, New York City, Philadelphia, Baltimore, and Washington, D.C.

In summary, of all the settlement types listed, a megalopolis is the largest as it comprises multiple, even significant urban areas that have expanded to form a vast, continuous area.

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When wet and dry bulb thermometers, which together form a psychrometer, record the same temperature, it indicates that the air is saturated. This means that the air has reached its maximum capacity to hold water vapor, also known as reaching the dew point.

Normally, the wet bulb thermometer, which has a cloth soaked in water wrapped around it, shows a lower temperature than the dry bulb thermometer because evaporation cools it down. However, when the temperatures are the same for both thermometers, no evaporation is taking place. This is because the air cannot accept more water vapor, pointing to a humidity level of 100%, which is known as saturation.

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The location of the iron and steel industry at Ajaokuta in Nigeria can be best explained by considering certain factors critical to the iron and steel production process. These factors include **availability of raw materials**, **efficient transportation networks**, and **proximity to fuel sources**.

Firstly, the presence of **iron ore at Itakpe** is crucial because iron ore is the primary raw material needed for steel production. The proximity of Itakpe's iron ore deposits to Ajaokuta reduces transportation costs and ensures a steady supply of the primary raw material, enhancing the industry's efficiency. Therefore, **availability of iron ore is a significant consideration**.

Secondly, **limestone at Ewekoro** is essential because limestone is a critical component used in removing impurities during the steelmaking process, particularly in the blast furnace. Limestone acts as a flux which combines with impurities and forms slag that can be easily removed. **Proximity to limestone sources ensures access to necessary materials for processing**, which is a factor in choosing the location of the industry.

The presence of a **river port at Lokoja** facilitates the transportation of raw materials and finished products, as waterways provide a cost-effective and efficient means of transportation. This is important for both importing required materials and exporting the finished steel products.

Additionally, **coal at Orukpa and Okaba** is important as coal is often used to generate the high temperatures needed in steel production, either directly or through the production of coke, a coal derivative used in blast furnaces.

In conclusion, the location of the iron and steel industry at Ajaokuta is best explained by the presence of:

• Iron ore at Itakpe, for the primary raw material.
• Limestone at Ewekoro, for aiding the processing in steelmaking.

Therefore, the most relevant factors are the **availability of iron ore and limestone**, making the best answer "I and II only".

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Mining in Africa faces several challenges, but understanding these issues helps in realizing the unique dynamics of the industry on the continent.

Inadequate Unskilled Labour: This is generally not a problem in Africa. The continent has a large population that provides sufficient unskilled labor for mining activities. Thus, an abundance of unskilled labor makes this factor not a significant issue for mining operations.

Use of Obsolete Technology: Many mining operations in Africa struggle with outdated or insufficient technology. This affects the efficiency and safety of mining activities, making it a significant challenge for the industry.

Shortage of Power: Power shortages are common in many African countries and can severely impact mining operations, which require consistent and significant energy for their activities. This is a critical challenge in mining across the continent.

Inadequate Foreign Capital: Many African nations experience difficulty in attracting sufficient foreign capital to invest in modernizing and expanding their mining sectors. This capital is crucial for technology upgrades and infrastructural development in the industry.

In summary, inadequate unskilled labour is not typically a problem for mining in Africa, whereas the other issues listed are significant challenges impacting the industry.

Answer Details

Coal is associated with organically-formed sedimentary rocks.

To understand why coal is associated with this type of rock, let's break it down:

1. **Sedimentary Rocks:** These rocks are formed from particles or sediments that accumulate and consolidate over time. Sedimentary rocks can be broken down further into different types based on their origins.

2. **Organically-formed Sedimentary Rocks:** This subgroup specifically forms from the accumulation of organic material, including plants and animals. Over millions of years, the remains of plants (especially those from swampy or wetland areas) accumulate in layers. As more and more layers build up, the pressure and heat from above cause these plant materials to transform into coal. Thus, coal is formed over long geological periods, through the compression of organic plant material.

This process differentiates organically-formed sedimentary rocks from mechanically-formed sedimentary rocks, which result from the mechanical process of weathering and erosion of existing rocks, and from igneous rocks like plutonic, which form from the solidification of magma, and crystalline rocks, which are typically associated with metamorphic processes. Thus, **coal is uniquely tied to organically-formed sedimentary rocks because of its plant-based origin**.