JAMB UTME - Geography - 2025

Awọn alaye Idahun

The Middle Belt of Nigeria has long been described in geography texts by three linked features: much of its land has historically supported comparatively low population density, it lies within a zone affected by insect pests and disease-carrying vectors such as the tsetse fly, and large tracts of its soil have been regarded as less productive than the richer alluvial soils found elsewhere in the country, partly because of leaching and erosion on its plateau and highland surfaces.

These three characteristics are not independent of one another. The presence of disease-carrying insects historically discouraged both human settlement and livestock keeping across parts of the Middle Belt, which in turn kept population figures low; sparse population and limited investment in soil management then contributed to lower agricultural productivity on much of the land. Because every one of the three specific statements offered, low soil productivity, presence of insect pests and disease vectors, and sparse population, matches a genuinely documented feature of the region, none of them is the false statement being sought.

A question asking which statement is not true is only answered by picking out a genuinely false claim from among the ones listed. Here, since all three descriptive statements about the Middle Belt hold up against known geography, the only logically consistent conclusion is that none of the given statements is untrue.

When a question of this kind offers a choice indicating that no false statement is present among those listed, test each statement individually before selecting it; it is only correct when every other statement survives scrutiny as true.

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Acid rain is a major environmental problem in heavily industrialised regions. It forms when sulphur dioxide (SO₂) and nitrogen oxides (NO_x) released from the burning of fossil fuels in factories, power plants, and vehicles react with water vapour, oxygen, and other chemicals in the atmosphere to form sulphuric acid and nitric acid. These acids then fall to the ground as acidic precipitation (rain, snow, fog, or dry deposition).

Acid rain causes widespread environmental damage in industrialised areas and their downwind neighbours:

• It corrodes buildings, monuments, and metal structures.
• It acidifies lakes and rivers, killing aquatic life.
• It damages forests by leaching nutrients from the soil and harming leaves.
• It degrades soil quality, reducing agricultural productivity.

Accelerated erosion and frost damage are not specifically linked to heavy industrialisation. Water pollution can occur in industrial areas but is a broader problem not unique to the most heavily industrialised regions. Acid rain, by contrast, is directly and characteristically caused by the high concentration of industrial emissions that define heavily industrialised regions.

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Fog forms when air is cooled to its dew point, causing water vapour to condense into tiny suspended water droplets near the ground. The type of fog described here is advection fog, which occurs when a mass of warm, moist air moves horizontally over a colder surface.

When a warm moist wind blows over a cold ocean current, the lower layers of the air mass are rapidly chilled by contact with the cold water. As the air temperature drops to the dew point, the moisture in the warm air condenses into fog. This is common along coastlines where warm and cold currents meet, such as off the coasts of Namibia (Benguela Current) and California (California Current).

The other scenarios are less effective at producing fog:

• A cold, dry wind over a warm current may pick up some moisture but is unlikely to reach saturation quickly enough to form dense fog.
• A warm moist wind over a warm current experiences little cooling, so condensation does not occur.
• A warm, dry wind over a cold current lacks sufficient moisture to produce fog even if cooling occurs.

The correct answer is that fog develops when a warm moist wind blows over a cold current.

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The Earth has two main motions: rotation (spinning on its axis, completing one turn every 24 hours) and revolution (orbiting the Sun, completing one circuit every 365.25 days). Each motion produces different phenomena.

Phenomena directly caused by rotation include:

• Night and day - as the Earth rotates, different parts face toward or away from the Sun.
• The deflection of winds and ocean currents (Coriolis effect).
• The apparent movement of the Sun across the sky.

Seasonal changes are caused by the Earth's revolution around the Sun combined with the tilt of the Earth's axis (23.5 degrees from the perpendicular to the orbital plane). As the Earth orbits the Sun, different hemispheres are tilted toward or away from the Sun at different times of the year, producing the seasons. Rotation plays no role in this process.

Varying duration of sunshine hours and unequal solar radiation on the Earth's surface are also consequences of the axial tilt and the Earth's spherical shape, but the question asks specifically about what is not directly related to rotation, and seasonal changes is the clearest answer since it depends entirely on revolution and axial tilt.

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A block mountain (also called a horst) is formed as a result of faulting. Specifically, it is produced when tectonic forces create two roughly parallel faults in the Earth's crust, and the block of land between or beside them is either pushed upward or remains elevated while the adjacent blocks subside. The upstanding block that results is the block mountain.

The process involves compressional or tensional forces in the Earth's crust that fracture rock along lines of weakness (faults). When the central block is pushed upward relative to the flanking blocks, it produces a horst. When the central block drops down instead, the resulting depression is called a graben or rift valley. Both features result from the same faulting mechanism.

Examples of block mountains include the Vosges and Black Forest mountains flanking the Rhine Rift Valley in Europe, and the Ruwenzori Mountains in East Africa.

Differential erosion shapes existing landforms but does not create block mountains. A fissure is simply a crack in rock. Vulcanicity produces volcanic mountains (such as Mount Kilimanjaro), which are fundamentally different in origin from block mountains.

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Marine (coastal) processes can be divided into erosion and deposition. A stack is a classic landform produced by marine erosion.

Stacks form through a sequence of erosional stages:

1. Waves attack lines of weakness (joints and faults) in a headland through hydraulic action, abrasion, and corrosion.
2. A cave is carved into the headland.
3. If caves form on both sides and eventually meet, an arch is created.
4. Continued erosion widens the arch until its roof collapses, leaving an isolated column of rock standing in the sea - this is a stack.

The other options are landforms produced by deposition, not erosion. A spit is a ridge of sand or shingle extending from the coast, formed by longshore drift. A beach is an accumulation of sand, pebbles, or shingle deposited by wave action. A mud-flat is a low-lying area of fine sediment deposited in sheltered coastal zones such as estuaries.

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Rye is not a plantation crop. Rye is a cereal grain grown primarily in temperate regions of Europe and North America. It is cultivated on small to medium-scale farms as a food crop (for bread, flour, and animal feed) and does not fit the plantation agriculture model.

Plantation crops are typically tropical or subtropical cash crops grown on large estates (plantations) using intensive labour, with the produce mainly destined for export or industrial processing. The key characteristics of plantation agriculture include large-scale monoculture, significant capital investment, and production for commercial rather than subsistence purposes.

The other three options are classic examples of plantation crops:

• Oil palm is grown on large plantations in tropical West Africa and Southeast Asia for palm oil production.
• Rubber is cultivated on plantations in tropical regions (Southeast Asia, West Africa) for latex and rubber products.
• Cocoa is grown on plantations in tropical West Africa (especially Ghana, Ivory Coast, Nigeria) for chocolate and beverage production.

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Frost action is not a process of chemical weathering. It is a process of physical (mechanical) weathering. Frost action (also called freeze-thaw weathering) occurs when water seeps into cracks in rocks and freezes. As water freezes, it expands by about 9%, exerting pressure on the surrounding rock. Repeated cycles of freezing and thawing gradually widen the cracks until pieces of rock break off. No chemical change occurs in this process.

The other three options are all genuine processes of chemical weathering:

• Hydrolysis is a chemical reaction between minerals in rock and water. Feldspar in granite, for example, reacts with water to form clay minerals (kaolinite), weakening the rock.
• Oxidation is the reaction between minerals (especially iron-bearing minerals) and oxygen in the presence of moisture. It produces iron oxides (rust), giving rocks a reddish-brown colour and making them crumble.
• Carbonation is the reaction between carbon dioxide dissolved in rainwater (forming weak carbonic acid) and calcium carbonate in limestone. The calcium carbonate dissolves, creating features such as caves, sinkholes, and karst landscapes.

Exam tip: Physical weathering breaks rock without changing its chemical composition. Chemical weathering alters the mineral composition of the rock through reactions with water, oxygen, or acids.

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The Middle Belt of West Africa is the sparsely populated transitional zone lying between the densely settled coastal south and the Sudano-Sahelian north. It stretches across parts of Nigeria, Ghana, Togo, Benin, and other West African countries.

The Middle Belt is characterised by:

• Few large towns - settlement is predominantly rural with scattered small villages.
• Low population densities - the area has historically been underpopulated due to factors such as tsetse fly infestation, poor accessibility, and inter-ethnic conflicts.
• Ethnic fragmentation - the zone contains a large number of small ethnic groups, unlike the more homogeneous populations in the far north and south.

However, much export crop production is NOT a characteristic of the Middle Belt. Export crops (also called cash crops) such as cocoa, rubber, and palm oil are concentrated in the wetter southern forest zone, while groundnuts and cotton dominate the northern savanna. The Middle Belt's agriculture is predominantly subsistence-oriented, focused on food crops like yams, guinea corn, millet, and cassava for local consumption rather than large-scale export production.

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The characteristics that are true of most large cities are having large populations (statement I) and being commercial centres (statement IV).

By definition, large cities have large populations. This is the primary criterion that makes them "large." Additionally, most large cities serve as major commercial centres, hosting markets, businesses, industries, financial institutions, and trade activities that drive economic growth. Commerce is a near-universal feature of large urban settlements.

Statement II (administrative centres) is not true of most large cities. While some large cities serve as national or regional capitals, many do not. For example, Lagos in Nigeria is the largest city but is not the federal capital (Abuja is). Similarly, Mumbai in India is larger than New Delhi, and Sao Paulo in Brazil is larger than Brasilia. Being an administrative centre is not a defining feature of city size.

Statement III (religious centres) is even less universally applicable. While some large cities like Rome or Mecca have religious significance, the vast majority of large cities are not primarily religious centres. Religious importance is incidental, not a characteristic of most large cities.

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The Nile Valley in Egypt is dominated by the Aswan High Dam, a large barrage built across the river to control its flow and store water in Lake Nasser. Beyond flood control and irrigation storage, the dam houses a major hydro-electric power station whose turbines convert the energy of the impounded water into electricity that is distributed across Egypt's national grid.

This large-scale generation of hydro-electric power from the Nile's flow is the feature of the Nile Valley most often highlighted in geography syllabuses when the valley's economic significance is discussed, because it represents a single engineered project that transformed the river's natural energy into a nationally important power supply. That is why hydro-electricity is identified as what the Nile Valley is best known for.

Industrial development, water navigation, and commerce all take place to some extent along the Nile, but none of them is as specifically and closely tied to the valley's defining infrastructure as the hydro-electric generation made possible by the Aswan High Dam.

When a question asks what a river valley is best known for, look for the single engineered or natural feature most consistently emphasised in textbooks, rather than listing every economic activity that happens to occur along its banks.

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Lake Malawi (also known as Lake Nyasa) owes its origin mainly to faulting. It occupies the southern end of the East African Rift System, a massive geological structure formed by tectonic forces pulling the African plate apart. As the Earth's crust was stretched and fractured, blocks of rock dropped down between parallel fault lines, creating a deep, narrow trough called a graben. Lake Malawi fills one of these grabens, reaching depths of over 700 metres.

Other rift valley lakes formed by the same faulting mechanism include Lake Tanganyika, Lake Albert, and Lake Turkana.

The other lakes have different origins:

• Lake Superior was shaped primarily by glacial erosion during the Pleistocene ice ages, when advancing ice sheets scoured and deepened pre-existing river valleys in North America.
• Lake Victoria is not a rift lake. It formed by down-warping (gentle sagging of the Earth's surface) between the eastern and western branches of the rift, creating a broad, shallow basin.
• Lake Chad occupies a shallow depression formed by gentle subsidence in the interior of West-Central Africa. It is an extremely shallow lake, unlike the deep rift lakes.

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The best location for a bakery is near a large market for bread. This is because bread is a perishable product that must reach consumers quickly while it is still fresh. Locating near the market (the consumers) minimises transport time and cost for the finished product and ensures the bread arrives fresh.

In industrial geography, this is an example of a market-oriented industry. Industries tend to locate near their market when:

• The finished product is more perishable or bulky than the raw materials
• The product gains weight or volume during production (bread dough expands during baking, and moisture is added)
• Consumer demand requires frequent, rapid delivery

The other factors are less decisive:

• A regular source of flour matters, but flour is a dry, non-perishable commodity that can be transported and stored easily.
• Cheap labour is not a primary consideration because modern bakeries are not highly labour-intensive.
• Clean water is important but is available from municipal supply in most locations.

For any perishable or weight-gaining product, proximity to the market is the most important locational factor.

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When a river's gradient changes from steep to gentle, its velocity decreases. A river's ability to transport sediment depends on its velocity and energy. As the gradient flattens and the water slows down, the river loses energy and can no longer carry its full sediment load. The river therefore begins depositing material.

This is a direct application of the Hjulstrom curve principle: faster-flowing water erodes and transports, while slower-flowing water deposits. The transition from a steep to a gentle gradient is exactly the condition that triggers deposition.

Common real-world examples of this process include:

• Alluvial fans - formed where a mountain stream meets a flat plain
• Flood plains and deltas - formed where rivers slow down on reaching low-lying areas or the sea
• Levees - built up when a river overflows its banks and immediately loses velocity

Erosion and deepening are dominant processes on steep gradients where the river has high velocity and energy. Terracing is an agricultural land-management technique, not a natural river process.

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An equatorial climate is characterised by high temperatures and heavy rainfall throughout the year, with no distinct dry season. To identify which pair of activities would NOT be found in this climate, consider what each activity requires:

• Commercial grain farming (activity 1) involves large-scale cultivation of cereals like wheat, maize, or barley. This requires a distinct dry season for harvesting and thrives in temperate grasslands (prairies, steppes, pampas), not in the constantly wet equatorial zone.
• Rice cultivation (activity 2) can thrive in equatorial regions because rice grows well in warm, waterlogged conditions.
• Lumbering (activity 3) is a major activity in equatorial regions, where dense tropical rainforests provide valuable hardwood timber.
• Plantation agriculture (activity 4) is well-suited to equatorial climates, producing crops such as rubber, oil palm, cocoa, and coffee.
• Dry farming (activity 5) is a technique used in arid and semi-arid areas with limited rainfall. It involves conserving soil moisture through specific tillage practices. This is entirely unsuitable for the equatorial zone, which has excessive rainfall year-round.

The two activities incompatible with an equatorial climate are therefore commercial grain farming and dry farming (activities 1 and 5). Both require drier conditions that the equatorial zone does not provide.

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The range of temperature for a station is the difference between the highest and lowest recorded temperatures over a given period. It is calculated as:

\[ \text{Range} = \text{Maximum temperature} - \text{Minimum temperature} \]

From the climate data table provided, the monthly temperatures (in °C) are:

Scanning across the row, the highest temperature is 30°C (recorded in August) and the lowest temperature is 16°C (recorded in January).

Substituting into the formula:

\[ \text{Range} = 30°C - 16°C = 14°C \]

The range of temperature for the station is therefore 14°C.

A common error is confusing the range with the mean (average) temperature or reading the wrong row (such as rainfall instead of temperature). Always identify the correct data row first, then pick out the single highest and single lowest values before subtracting.

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Enugu is not a pre-colonial town. It was established and developed in the early twentieth century by the British colonial administration following the discovery of coal deposits in the area in 1909. The town grew as a coal-mining centre and later became the capital of the Eastern Region of Nigeria under colonial rule. Its origin and growth are directly tied to colonial economic activity.

The other towns all existed before the arrival of European colonisers:

• Bida is an ancient town and the seat of the Nupe kingdom (the Etsu Nupe), with origins predating colonial contact.
• Ilorin was an important Yoruba town that became the capital of an emirate in the early 19th century under Fulani rule, well before British colonisation.
• Ibadan was founded around 1829 as a war camp by Yoruba warriors and grew into one of the largest cities in pre-colonial West Africa.

Awọn alaye Idahun

Inter-regional trade within West Africa has been promoted mainly by deliberate government policies in recent times. The most significant of these is the establishment of the Economic Community of West African States (ECOWAS) in 1975, which was created specifically to promote economic cooperation and integration among member states.

Key policy measures that have facilitated intra-regional trade include:

• Reduction and elimination of tariff barriers between member countries
• The ECOWAS Trade Liberalisation Scheme (ETLS), which allows duty-free movement of goods produced within the community
• Free movement of persons across borders, encouraging cross-border commerce
• Development of transport corridors connecting member states

The other options would actually hinder rather than promote inter-regional trade. Competition among nations without cooperation frameworks does not facilitate trade. The production of similar goods across West African countries reduces the incentive for trade, since each country can meet its own needs. Relationships with former colonial rulers historically oriented trade outward toward Europe rather than between African neighbours, as colonial infrastructure was designed to export raw materials to the metropole, not to connect African countries with each other.

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The industrial belt of Japan produces ships, electronics, and motor vehicles. Japan is one of the world's leading industrial nations, and its industrial belt (concentrated along the Pacific coast in the Tokaido corridor, stretching from Tokyo through Nagoya to Osaka and Kobe, and extending to Kitakyushu) is renowned for these three major product categories.

• Shipbuilding has been a major Japanese industry since the post-war era, with companies operating large shipyards along the coast.
• Electronics is one of Japan's signature industries. Japanese companies are global leaders in semiconductors, consumer electronics, precision instruments, and electronic components.
• Motor vehicles represent Japan's single most valuable export category. Japanese automobile manufacturers are among the largest in the world, producing millions of vehicles annually for both domestic use and export.

The other options do not accurately describe Japan's industrial output. Japan is not primarily associated with warships and ammunitions as main industrial products, nor with agricultural machinery like combined harvesters. While Japan does produce some pharmaceutical and leather products, these are not the defining outputs of its industrial belt.

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The vegetation of the warm Temperate Eastern Margin climate (also known as the China type or humid subtropical climate) is characterised by mixed coniferous and broad-leaved evergreen forests.

This climate type is found on the eastern sides of continents between approximately 25 and 40 degrees latitude, including southeastern China, southern Japan, southeastern United States, southeastern Brazil, and eastern Australia. It receives adequate rainfall throughout the year (with a summer maximum) and has warm summers and mild winters.

The natural vegetation reflects these conditions: broad-leaved evergreen trees (such as laurels, magnolias, and camphor trees) thrive in the warm, moist environment, while coniferous trees (such as pines and cypresses) are also present, especially at slightly higher elevations or in areas with cooler winters. The result is a mixed forest of both types.

Evergreen shrubs and thickets are more typical of the Mediterranean (warm Temperate Western Margin) climate. Mixed deciduous and coniferous forests characterise the cool Temperate Continental climate. Mixed tropical rainforests and monsoonal forests belong to equatorial and tropical monsoon zones, not the warm temperate margin.

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Among the industrial zones listed, Lokoja-Ajaokuta is the least industrialised in Nigeria.

Although the Ajaokuta Steel Company was established in the 1970s with the aim of becoming a major industrial hub, the steel complex has never operated at full capacity and has faced decades of mismanagement, incomplete construction, and policy challenges. Lokoja, the Kogi State capital, is primarily an administrative and trading centre with minimal manufacturing activity.

By contrast:

• Lagos-Ikeja is Nigeria's most industrialised zone, hosting the largest concentration of manufacturing industries, port facilities, and commercial enterprises in the country.
• Port Harcourt-Aba is a major industrial zone driven by the petroleum industry, petrochemicals, and a thriving manufacturing sector in Aba.
• Kaduna-Zaria is an established industrial zone in northern Nigeria, with textile mills, vehicle assembly plants, and other manufacturing industries.

Awọn alaye Idahun

The correct distinction between rotation and revolution is that the Earth rotates on its axis while it revolves round the sun on an elliptical orbit.

Rotation is the spinning of the Earth on its own imaginary axis (an imaginary line running from the North Pole to the South Pole). One complete rotation takes approximately 24 hours and is responsible for the alternation of day and night.

Revolution is the movement of the Earth around the Sun along an elliptical (slightly oval-shaped) path called an orbit. One complete revolution takes approximately 365.25 days (one year) and is responsible for the change of seasons, variation in the length of day and night throughout the year, and the apparent movement of the overhead sun between the tropics.

The other options contain factual errors:

• Revolution does not cause day and night; rotation does. And rotation does not cause seasons; revolution (combined with the tilt of the Earth's axis) does.
• Revolution does not take 24 hours; it takes approximately 365.25 days. Rotation does not mark a year; it marks a day.
• Rotation does not cause variation in the lengths of day and night; revolution and axial tilt do. Neither rotation nor revolution causes tides (tides are caused by gravitational pull of the moon and sun).

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This question applies the environmental lapse rate in reverse. Instead of calculating the temperature at a higher altitude, you must calculate the temperature at a lower altitude (the foot of the volcano) given the temperature at the peak.

The environmental lapse rate states that temperature decreases by approximately 6.5 \(^\circ\)C for every 1000 metres of altitude gained. Conversely, temperature increases by 6.5 \(^\circ\)C for every 1000 metres of descent.

Given information:

• Temperature at the peak = 6 \(^\circ\)C
• Height of the volcano = 3000 m above the surrounding lowland
• Lapse rate = 6.5 \(^\circ\)C per 1000 m

Calculation:

Temperature at the foot:

The temperature at the foot of the volcano is 25.5 \(^\circ\)C.

Awọn alaye Idahun

Gold is Ghana's most important industrial mineral. Ghana was historically known as the Gold Coast precisely because of its abundant gold deposits, and gold mining remains the country's leading mineral industry and a major source of export revenue.

Ghana is one of the largest gold producers in Africa, with major mining operations at Obuasi (operated by AngloGold Ashanti), Tarkwa, and other sites in the Ashanti and Western regions. The gold mining sector is the backbone of Ghana's mining industry and contributes significantly to government revenue and employment.

While Ghana also has deposits of bauxite (at Awaso and Nyinahin) and diamonds (at Akwatia), these are of secondary importance compared to gold. Bauxite mining feeds into aluminium smelting at the Volta Aluminium Company (VALCO) smelter in Tema, but the scale and economic impact of the gold industry far exceeds that of bauxite or diamond mining in Ghana.

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Canada is one of the world's leading countries in commercial grain farming. The Canadian Prairies (Alberta, Saskatchewan, and Manitoba) form one of the largest commercial grain-producing regions in the world, with wheat being the principal crop. Canada is consistently among the top global exporters of wheat, barley, and canola.

Commercial grain farming is characterised by:

• Large-scale, highly mechanised operations covering vast areas of flat land.
• Production primarily for sale and export rather than subsistence.
• A temperate continental climate with warm summers suitable for grain cultivation.

Spain has a diversified agricultural sector including olives, wine, and fruits, but is not primarily known for commercial grain farming on the scale of Canada. Kenya's agriculture is dominated by cash crops (tea, coffee, flowers) and subsistence farming. Nigeria's agriculture is largely subsistence-based with some commercial crops (cocoa, palm oil, rubber), but not large-scale commercial grain farming in the way Canada practises it.

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A wadi is a feature produced by water in desert areas. A wadi is a valley, ravine, or channel that is dry for most of the year but carries water during occasional heavy rainstorms. The intermittent but sometimes torrential flow of water carves out these channels through erosion over time, creating distinctive dry valleys across desert landscapes.

Wadis are common in the Sahara Desert, the Arabian Desert, and other arid regions. They are important because they indicate the work of running water even in environments where water is scarce. After rain, wadis may fill rapidly and produce flash floods before drying out again.

The other options are all features produced by wind action, not water:

• Barchans are crescent-shaped sand dunes formed by wind deposition.
• Yardangs are elongated, streamlined ridges carved by wind abrasion.
• Zeugens are tabular rock formations where wind abrasion has eroded softer lower layers, leaving a harder caprock on top (mushroom-shaped rocks).

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Ocean currents are classified as either warm or cold depending on whether their water temperature is higher or lower than the surrounding ocean water. Warm currents flow from equatorial regions toward the poles, while cold currents flow from polar regions toward the equator.

The Mozambique current is a warm current. It flows southward along the coast of Mozambique in the Indian Ocean, carrying warm tropical water from near the equator toward higher latitudes. It warms the southeastern coast of Africa and eventually feeds into the Agulhas Current.

The other three currents are all cold:

• The Benguela current flows northward along the south-west coast of Africa, carrying cold water from the Southern Ocean and producing the cool, dry conditions of the Namib Desert.
• The Labrador current flows southward from the Arctic along the north-east coast of North America, bringing cold water and icebergs past Newfoundland.
• The Canaries current flows southward along the north-west coast of Africa, carrying cool water from higher latitudes and contributing to the aridity of the western Sahara coastline.

A reliable pattern to remember: currents flowing from the equator toward the poles are warm; those flowing from the poles toward the equator are cold.

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This question tests the concept of the environmental lapse rate, which states that temperature decreases by approximately 6.5 \(^\circ\)C for every 1000 metres of altitude gained in the troposphere.

Given information:

• Surface temperature = 40 \(^\circ\)C
• Altitude of the aeroplane = 4000 m
• Lapse rate = 6.5 \(^\circ\)C per 1000 m

Calculation:

Temperature drop = lapse rate \(\times\) altitude (in thousands of metres)

Temperature at 4000 m:

The temperature around the aeroplane at 4000 metres altitude is 14 \(^\circ\)C.

Exam tip: Always use the standard environmental lapse rate of 6.5 \(^\circ\)C per 1000 m unless a different rate is specified in the question. Convert altitude to kilometres before multiplying.

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Africa extends roughly from about 17 degrees W at its westernmost point (Cape Verde, Senegal) to about 51 degrees E at its easternmost point (Cape Guardafui, Somalia). To find the longitude that bisects the continent into approximately equal eastern and western halves, we look for the meridian near the middle of this range.

The longitude of 20 degrees E runs through the heart of Africa, passing through countries such as Libya, Chad, Cameroon, the Democratic Republic of Congo, and Namibia. It divides the continent into roughly equal portions to the east and west.

The other options do not bisect Africa equally:

• 20 degrees W lies in the Atlantic Ocean, west of the African mainland.
• 40 degrees E passes through the eastern part of Africa (Ethiopia, Kenya, Tanzania), leaving the vast majority of the continent to the west.
• 40 degrees W lies deep in the Atlantic Ocean, far from Africa.

The correct answer is 20 degrees E.

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Mixed farming is an agricultural system in which a farmer both grows crops and rears animals on the same farm or land area. The crops and livestock complement each other: crop residues and by-products can be used as animal feed, while animal manure enriches the soil for crop production.

This is distinct from:

• Growing different types of crops together (such as grains and root crops on the same land), which is better described as mixed cropping or intercropping.
• Keeping different types of livestock together (poultry and pigs), which is simply diversified livestock farming.
• Cultivating multiple grain crops (wheat, barley, and oats), which is a form of arable farming with crop diversification, not mixed farming in the standard geographic sense.

The defining feature of mixed farming is the combination of crop cultivation and animal husbandry as integrated activities on a single farm unit.

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More Hydroelectric Power (HEP) projects should be constructed in Tropical Africa because there is an increasing demand for power. Tropical Africa is experiencing rapid population growth, urbanisation, and industrialisation, all of which drive a growing need for electricity. Many areas still lack reliable power supply, and the demand for energy far outstrips current generating capacity.

Tropical Africa has excellent natural conditions for hydroelectric power: abundant rainfall feeds large rivers with high and consistent discharge, and the terrain includes numerous waterfalls, rapids, and steep gradients that provide the head of water needed to generate electricity. Existing HEP projects such as the Akosombo Dam (Ghana), Kainji Dam (Nigeria), and Inga Dam (Democratic Republic of Congo) demonstrate this potential, but much of it remains untapped.

The other options actually describe obstacles or irrelevant factors rather than reasons for building more HEP:

• Scarcity of skilled labour is a challenge to construction, not a reason to build more projects.
• There is no absence of waterfalls on rivers in Tropical Africa; on the contrary, the region has many suitable sites.
• Tropical Africa receives abundant rainfall, not scanty rainfall. High rainfall ensures the rivers needed for HEP are well supplied with water.

Awọn alaye Idahun

Zambia is the country whose export trade is dominated by a single mineral: copper. Zambia sits on the Copperbelt, one of the world's richest copper-mining regions, and copper has historically accounted for the vast majority of the country's export earnings. This heavy dependence on a single mineral export makes Zambia a classic example of a mono-mineral economy.

The other countries do not have exports dominated by a single mineral:

• The Central African Empire (now the Central African Republic) has some diamond mining, but its economy is not as heavily dependent on one mineral as Zambia's is on copper.
• Kenya has a diversified export base led by agricultural products such as tea, coffee, and horticultural products (flowers and vegetables), along with tourism revenue.
• Uganda similarly relies on agricultural exports, particularly coffee, tea, and fish, rather than mineral exports.

Zambia's extreme dependence on copper exports has made the country vulnerable to fluctuations in global copper prices, illustrating the economic risks of relying on a single commodity.

Awọn alaye Idahun

The rapid increase in world population during the twentieth century is primarily explained by the fact that death rates decreased rapidly while birth rates remained relatively high, especially in developing countries.

Advances in medicine (antibiotics, vaccines, surgical techniques), improved sanitation and clean water supply, better nutrition, and public health campaigns dramatically reduced mortality from infectious diseases, infant mortality, and maternal mortality. Life expectancy increased substantially across the globe. This meant that more people survived to reproductive age and lived longer, leading to rapid population growth.

This phenomenon is described in the demographic transition model: Stage 2 of the model shows death rates falling sharply while birth rates remain high, producing a large natural increase in population.

Increasing food production helped sustain the growing population but was not the primary demographic driver. The abolition of the slave trade occurred in the 19th century and did not directly cause twentieth-century population growth. Birth rates have actually declined in most parts of the world during the twentieth century, not increased; it was the gap between still-high birth rates and rapidly falling death rates that caused the population surge.

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Freetown, the capital of Sierra Leone, has the highest mean annual rainfall among these cities, receiving approximately 3,600 mm per year. It ranks among the wettest capital cities in Africa.

Freetown's exceptionally high rainfall is explained by its location and relief:

• It sits on the coast of West Africa directly in the path of the moisture-laden south-west monsoon winds blowing from the Atlantic Ocean.
• The Freetown Peninsula mountains (rising to about 900 m) force these moist winds upward, producing intense orographic (relief) rainfall in addition to the convectional rainfall common to the region.

By comparison, Lagos receives about 1,600 mm annually, while Accra and Lome are notably drier (around 800 mm each) because they lie in a rain shadow zone along the Gulf of Guinea coast where the coastline runs parallel to the prevailing winds, reducing moisture uplift.

When comparing rainfall totals for West African cities, remember that orographic factors can greatly amplify rainfall where highland terrain faces onshore winds.

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Hydraulic action is a process of wave erosion. It occurs when waves crash against rock surfaces and force air into cracks and joints in the rock. The repeated compression and expansion of trapped air exerts enormous pressure, gradually weakening and breaking apart the rock. This is one of the primary ways waves erode coastlines, forming features such as cliffs, caves, arches, and stacks.

The other options are all processes of transportation, not erosion:

• Saltation is the bouncing movement of particles along a surface, carried intermittently by wind or water.
• Traction involves large, heavy particles being rolled or dragged along the bed by the force of moving water or wind.
• Suspension is the carrying of fine, light particles within the body of moving water or air.

The key distinction is that erosion refers to the wearing away and removal of rock material, while transportation refers to how already-eroded material is moved from one place to another.

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The wearing away of the sides and bottom of a river's channel is called corrosion. In the context of river erosion as used in many West African geography curricula, corrosion refers to the grinding and scraping action of the river's sediment load (sand, pebbles, boulders) against the bed and banks of the channel. This is also known as abrasion or corrasion in some textbooks.

The other types of erosion have different meanings:

• Attrition is the process by which transported rock fragments collide with each other and are gradually worn down into smaller, more rounded particles. It acts on the load itself, not on the channel.
• Hydraulic action is the force of the water itself against the banks and bed, including the pressure of water being forced into cracks. It does not involve the grinding action of sediment.
• Corrosion action is not a standard geographical term and serves as a distractor in this question.

When distinguishing between river erosion processes, remember: corrosion (abrasion) wears the channel using the river's load as a tool, attrition wears the load itself, and hydraulic action uses the sheer force of water alone.

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Coastal lands adjacent to cool ocean currents experience a distinctive climate pattern characterised by winter rain and summer drought. This is associated with the Mediterranean climate type.

Cool ocean currents (such as the Canary Current off northwest Africa, the Benguela Current off southwest Africa, and the California Current off the western United States) affect adjacent coastlands in specific ways:

• In summer, the cool current chills the air above the ocean surface, creating a stable atmosphere that suppresses convection and rainfall. Onshore winds bring fog and mist but very little actual precipitation, resulting in drought conditions.
• In winter, the subtropical high-pressure belt shifts equatorward, allowing mid-latitude westerlies to bring cyclonic (frontal) rainfall to these coastal areas.

This combination produces the winter-rain, summer-drought pattern. The monsoon pattern is associated with seasonal wind reversal in South and Southeast Asia. Rain all year round is typical of equatorial climates. Summer rain with winter drought describes tropical savanna climates influenced by the seasonal shift of the Inter-Tropical Convergence Zone (ITCZ).

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Loess is a wind-deposited landform. It consists of fine-grained, yellowish-brown sediment (mainly silt) that has been picked up by wind from desert surfaces, dried-up riverbeds, or glacial outwash plains and deposited over wide areas, sometimes hundreds of kilometres from its source. Loess deposits can accumulate to considerable thicknesses and form fertile soils, as seen in the Loess Plateau of China and parts of central Europe and the American Midwest.

The process that creates loess is aeolian (wind) deposition: wind carries fine particles in suspension over long distances and gradually deposits them when wind speed decreases.

The other options are all landforms produced by wind erosion, not deposition:

• A yardang is an elongated, streamlined rock ridge sculpted by wind abrasion in desert environments.
• A rock pedestal (mushroom rock) is formed when wind-blown sand erodes the base of a rock more than the top, creating a top-heavy pillar shape.
• A deflation hollow is a depression formed when wind removes loose, fine-grained material from the surface, lowering the ground level.

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Adequate publicity about natural scenery is a major boost to tourism. When a destination's natural beauty, landscapes, wildlife, and unique geographic features are well publicised through media, advertising campaigns, documentaries, and travel literature, it attracts tourists by raising awareness and generating interest in visiting those places.

Tourism depends heavily on information reaching potential visitors. Countries and regions that invest in promoting their natural attractions (waterfalls, beaches, mountains, national parks, wildlife reserves) tend to attract significantly more tourists than those with equal natural endowments but poor publicity.

A higher dependency ratio describes a population with many non-working-age dependants relative to the working-age population. This is an economic burden indicator, not something that promotes tourism. Variation in mode of transportation may facilitate travel logistics but is not itself a primary driver of tourism demand.

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Hydromorphic soil is the heavy, dark soil associated with floodable valley bottoms. The term "hydromorphic" literally means "water-shaped," indicating soil that has been significantly influenced by the presence of water.

Hydromorphic soils develop in areas where waterlogging is frequent or prolonged, such as river floodplains, valley bottoms, swamps, and deltas. They are characteristically heavy (high clay content) and dark in colour due to the accumulation of organic matter that decomposes slowly under waterlogged, anaerobic conditions. These soils often have a gleyed horizon (grey-blue layer) resulting from the chemical reduction of iron in oxygen-poor conditions.

The other soil types form under different conditions:

• Lateritic soil is a reddish, iron-rich soil formed by intense tropical weathering in well-drained upland areas.
• Ferrallitic soil is a deep, heavily leached tropical soil rich in iron and aluminium oxides, typically red or yellow.
• Podzolic soil forms in cool, humid climates under coniferous forests, with a distinctive leached, ash-grey layer.