All practice questions

Question 12361Question →

Which of the following environmental conservation methods involves planting trees on land that previously had no forest cover to help reduce atmospheric carbon dioxide and control soil degradation?

Afforestation

Deforestation

Fossil fuel combustion

Environmental Impact Scoping

Show answer & explanation

Answer: Afforestation

Answer

Afforestation is the targeted establishment of new forests on previously non-forested land to combat soil erosion and absorb atmospheric carbon dioxide.

Afforestation directly introduces tree cover to non-forested areas, acting as a biological conservation technique that stabilizes topsoil, restores ecosystem structure, and captures carbon dioxide.

Step-by-Step Solution

1

Identify the conservation technique described in the stem.

The technique requires planting trees on land without prior forest cover.

Biological conservation techniques rely on vegetation to stabilize soil and capture carbon.

2

Distinguish afforestation from other environmental management terms.

Afforestation creates new forests, whereas reforestation replaces lost forests and deforestation destroys them.

Understanding precise environmental terminology is necessary to select the correct conservation method.

Key Concept

Biological Methods of Environmental Conservation: Afforestation

Question 12362Question →

A topographical map extract shows a series of streams radiating outward from a central dome, with subsequent tributaries capturing flow along concentric ring valleys formed on eroded sedimentary layers. Which drainage pattern is illustrated by this stream arrangement?

Annular pattern

Radial pattern

Centripetal pattern

Trellis pattern

Show answer & explanation

Answer: Annular pattern

Answer

Annular drainage pattern

Annular drainage develops on maturely dissected domes where alternating concentric bands of hard and soft rock are exposed. Main streams flow outward from the dome, while tributary streams carve circular, ring-like channels along the softer rock belts.

Step-by-Step Solution

1

Analyze the structural landform and elevation description in the stem.

Identified a dissected dome structure with elevated center and concentric belts of contrasting rock hardness.

Geological structure dictates the structural control governing drainage network development.

2

Evaluate stream geometry and flow direction.

Streams flow outwards from the high central region, while tributary streams follow curved concentric bands of weaker rock.

Differential erosion creates circular valleys where tributaries flow along rings around the central dome.

3

Match the observed stream geometry to standard genetic drainage patterns.

The ring-like or circular pattern around a central upland is classified as annular drainage.

Annular pattern is defined by concentric ring-like stream paths formed on breached domes or maturely dissected structural domes.

Key Concept

Annular Drainage Pattern and Structural Controls

Estimated Time:1m 15s

Question 12363Question →

In hilly regions of Nigeria, such as the slopes of the Jos Plateau, extensive removal of vegetation often causes loose surface soil and rock debris to slide rapidly downslope under the direct influence of gravity. Which of the following hazards best describes this bulk movement of material?

Mass wasting

Weathering

Sheet erosion

Soil salinization

Show answer & explanation

Answer: Mass wasting

Answer

Mass wasting

Mass wasting describes the bulk downslope movement of soil, regolith, and weathered rock fragments primarily driven by gravity. Deforestation on steep slopes destabilizes the ground surface, making mass wasting events like landslides and mudflows more frequent.

Step-by-Step Solution

1

Analyze the primary force and mode of transport in the scenario

The process involves soil and rock moving downslope driven by gravity following vegetation loss.

Determining whether movement is driven directly by gravity or by water/wind flow identifies the hazard category.

2

Differentiate downslope bulk movement from in-situ disintegration

Disintegration occurring in place without transportation is weathering, whereas bulk downslope movement driven by gravity is mass wasting.

Mass wasting specifically describes gravitational slope failure and downslope displacement.

Key Concept

Mass wasting as a gravity-driven environmental hazard

Estimated Time:1m 0s

Question 12364Question →

A meteorological vessel measures its local solar time to be $3:20\text{ p.m.}$ when Greenwich Mean Time ( $0^\circ$ ) is $11:00\text{ a.m.}$ on the same day. What is the longitude of the vessel in degrees East?

Show answer & explanation

Answer: 65

Answer

The longitude of the vessel is

65^\circ\text{E}

.

The time difference between

3:20\text{ p.m.}

and

11:00\text{ a.m.}

is 4 hours and 20 minutes (

260\text{ minutes}

). Since the Earth rotates

1^\circ

every 4 minutes,

260\text{ minutes} \div 4 = 65^\circ

. Because the vessel's local solar time is ahead of Greenwich Mean Time, the vessel is located east of the Prime Meridian, yielding

65^\circ\text{E}

.

Step-by-Step Solution

1

Calculate time difference

4 hours 20 minutes (260 minutes)

Subtract GMT (11:00 a.m.) from local solar time (3:20 p.m.).

2

Convert time difference to longitude degrees

65 degrees

Divide total time difference in minutes (260) by 4 minutes per degree of Earth's rotation.

3

Determine longitudinal hemisphere

East

Local time is ahead of GMT, which indicates a position to the east of the Prime Meridian.

Key Concept

Calculation of longitude from local time and Greenwich Mean Time (GMT) using Earth's rotation rate

Question 12365Question →

A trans-African infrastructure corridor is planned along the line of the Equator ( $0^\circ$ latitude), traversing the continent continuously from the Atlantic Ocean on the west to the Indian Ocean on the east. Which of the following lists, in strict geographical order from west to east, the mainland African sovereign nations through which the line of the Equator passes?

Gabon, Republic of the Congo, Democratic Republic of the Congo, Uganda, Kenya, and Somalia

Somalia, Kenya, Uganda, Democratic Republic of the Congo, Republic of the Congo, and Gabon

Cameroon, Central African Republic, Democratic Republic of the Congo, South Sudan, Ethiopia, and Somalia

Gabon, Equatorial Guinea, Republic of the Congo, Rwanda, Burundi, and Tanzania

Show answer & explanation

Answer: Gabon, Republic of the Congo, Democratic Republic of the Congo, Uganda, Kenya, and Somalia

Answer

The correct sequence of mainland African sovereign nations traversed by the Equator (

0^\circ

latitude) from west to east is Gabon, Republic of the Congo, Democratic Republic of the Congo, Uganda, Kenya, and Somalia.

The correct answer accurately tracks the latitudinal line of

0^\circ

(the Equator) across mainland Africa starting from Gabon on the Atlantic coast, progressing eastward through the Republic of the Congo, the Democratic Republic of the Congo, Uganda, and Kenya, and reaching the Indian Ocean coast in Somalia.

Step-by-Step Solution

1

Identify the westernmost mainland entry point of the Equator (

0^\circ

latitude) on the Atlantic coast.

The Equator enters mainland Africa through the Atlantic coastal nation of Gabon.

Gabon forms the western landfall point for the equatorial parallel.

2

Trace the equatorial parallel eastward across Central Africa.

After Gabon, the Equator crosses the Republic of the Congo (Congo-Brazzaville) and then the vast territory of the Democratic Republic of the Congo (DRC).

These two nations occupy the central equatorial belt of Africa.

3

Trace the line across East Africa to its exit point on the Indian Ocean.

Continuing eastward from the DRC, the Equator crosses Uganda, passes through Kenya, and exits into the Indian Ocean through Somalia.

Uganda, Kenya, and Somalia form the East African segment of the

0^\circ

parallel.

Key Concept

Latitudinal Position and Political Divisions of Equatorial Africa

Estimated Time:2m 0s

Question 12366Question →

Arrange the following fundamental stages of an Environmental Impact Assessment (EIA) in their correct procedural sequence from start to finish.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct procedural sequence of Environmental Impact Assessment (EIA) stages is: 1. Screening project necessity, 2. Scoping key issues and boundaries, 3. Baseline environmental data collection and impact prediction, and 4. Preparation of the final Environmental Impact Statement (EIS).

The standard EIA workflow begins with screening to evaluate if the project requires assessment. Once established, scoping determines the critical issues to study. Next, baseline data is collected and environmental impacts are predicted. Finally, the findings are compiled into an Environmental Impact Statement (EIS) for review.

Step-by-Step Solution

1

Identify the initial evaluation step.

Screening is identified as the first stage because it determines if a project warrants an EIA.

Before resources are spent on detailed studies, regulatory screening must confirm whether an EIA is mandatory.

2

Determine the scope and key focus areas.

Scoping follows screening immediately.

Scoping defines the key parameters, relevant issues, and boundary conditions to focus the subsequent environmental investigation.

3

Analyze current conditions and model impacts.

Baseline data collection and impact prediction form the third stage.

Field investigations gather current ecological and social baseline data to quantify and predict expected impacts.

4

Document and synthesize all findings.

Preparation of the Environmental Impact Statement (EIS) is the final stage among the listed steps.

All collected data, predictions, and proposed mitigation strategies are synthesized into an official report for agency review.

Key Concept

Stages of Environmental Impact Assessment (EIA)

Question 12367Question →

Under the provisions of the National Environmental Standards and Regulations Enforcement Agency (NESREA) Establishment Act, NESREA holds statutory authority to enforce environmental compliance within the upstream oil and gas sector in Nigeria.

True

False

Show answer & explanation

Answer: False

Answer

The statement is False.

The statement is false because the National Environmental Standards and Regulations Enforcement Agency (NESREA) Establishment Act of 2007 explicitly exempts the petroleum industry from NESREA's regulatory enforcement domain. Environmental protection, monitoring, and spill detection within Nigeria's oil and gas sector are assigned to the National Oil Spill Detection and Response Agency (NOSDRA) alongside sectoral petroleum regulatory commissions.

Step-by-Step Solution

1

Identify the legal statute and regulatory agency specified in the statement.

The statement references NESREA and its enforcement powers under the NESREA Establishment Act of 2007.

Determining statutory jurisdiction requires examining the founding legislation of the agency in question.

2

Analyze the statutory scope and legal exemptions governing NESREA's mandate.

Section 7 of the NESREA Act mandates the agency to enforce compliance with environmental laws across all sectors EXCEPT the oil and gas sector.

Nigerian law assigns petroleum-related environmental regulation and spill response to specialized entities like NOSDRA to avoid duplicate regulatory authority.

3

Conclude the accuracy of the assertion regarding NESREA's powers in upstream petroleum operations.

Because NESREA is legally restricted from enforcing environmental regulations in the upstream oil and gas industry, the statement is false.

Asserting that NESREA has regulatory enforcement jurisdiction over oil and gas operations directly contradicts the statutory exemption defined in its establishing law.

Key Concept

Statutory Exemptions and Jurisdictional Boundaries of Nigerian Environmental Agencies

Question 12368Question →

A sole proprietor, Kemi, began the financial year with an opening capital of $₦1,800,000$ . During the year, the business earned a net profit of $₦450,000$ . In the same period, Kemi withdrew $₦60,000$ in cash for personal use, took business inventory costing $₦40,000$ (with a retail selling price of $₦55,000$ ) for private domestic consumption, and paid a personal residential utility bill of $₦25,000$ directly from the business bank account. What is the value of Kemi's capital at the end of the financial year?

₦2,125,000

₦2,110,000

₦2,375,000

₦2,165,000

Show answer & explanation

Answer: $₦2,125,000$

Answer

The value of Kemi's capital at the end of the financial year is

₦2,125,000

.

The correct closing capital is calculated by taking Opening Capital (

₦1,800,000

), adding Net Profit (

₦450,000

), and subtracting Total Drawings (

₦125,000

). Total drawings include cash withdrawn (

₦60,000

), goods withdrawn at cost (

₦40,000

), and personal bills paid using business funds (

₦25,000

). This gives

₦1,800,000 + ₦450,000 - ₦125,000 = ₦2,125,000

.

Step-by-Step Solution

1

Calculate total drawings made by the owner during the period.

Total Drawings =

₦60,000

(cash) +

₦40,000

(goods at cost) +

₦25,000

(personal bill paid) =

₦125,000

.

Goods withdrawn for personal use must be recorded at cost price, and business cash paid for personal expenses is treated as drawings under the business entity concept.

2

Apply the closing capital formula for a sole trader.

Closing Capital = Opening Capital + Net Profit - Drawings =

₦1,800,000 + ₦450,000 - ₦125,000 = ₦2,125,000

.

Net profit increases equity while total drawings decrease equity in the Statement of Financial Position.

Key Concept

Treatment of Owner's Capital, Drawings, and Goods Withdrawn

Estimated Time:1m 30s

Question 12369Question →

The table below presents the age structure of a municipal population in Nigeria obtained during a demographic survey:

Age Group (Years)	Population
$0 - 14$	$70,000$
$15 - 64$	$110,000$
$65+$	$20,000$

Based on these demographic data, what is the total age dependency ratio of this population?

45.00\%

81.82\%

122.22\%

63.64\%

Show answer & explanation

Answer: $81.82\%$

Answer

The total age dependency ratio of the population is

81.82\%

.

The total age dependency ratio measures the demographic burden placed on the economically active population (

15-64

years). Combining the youth population (

70,000

) and old-age population (

20,000

) gives a total dependent cohort of

90,000

. Dividing this by the working-age population (

110,000

) and multiplying by

100

yields approximately

81.82\%

.

Step-by-Step Solution

1

Identify the dependent population cohorts

Dependent population =

70,000 \text{ (aged 0-14)} + 20,000 \text{ (aged 65+)} = 90,000

Dependents consist of individuals under 15 years old and individuals aged 65 and above.

2

Identify the economically active (working-age) population

Working-age population =

110,000 \text{ (aged 15-64)}

The working-age group supports the dependent population.

3

Apply the total age dependency ratio formula

\text{Dependency Ratio} = \left( \frac{\text{Dependent Population}}{\text{Working-Age Population}} \right) \times 100 = \left( \frac{90,000}{110,000} \right) \times 100 \approx 81.82\%

The standard demographic metric measures the ratio of dependents per 100 working-age individuals.

Key Concept

Age Dependency Ratio

Estimated Time:1m 30s

Question 12370Question →

Match each seismic discontinuity of the Earth's interior in Column I with its defining structural interface or wave behavior in Column II. Which alignment correctly matches each discontinuity to its boundary feature?

Click a left item, then click its matching right item

Show answer & explanation

Answer

Conrad Discontinuity corresponds to the intra-crustal boundary between SIAL and SIMA; Mohorovičić Discontinuity corresponds to the boundary between the crust and mantle; Gutenberg Discontinuity corresponds to the core-mantle boundary where S-waves drop to zero; Lehmann Discontinuity corresponds to the boundary between the liquid outer core and solid inner core.

Each discontinuity represents a specific geophysical transition within the Earth's interior. The Conrad discontinuity is intra-crustal (SIAL/SIMA), the Mohorovičić discontinuity is crust-mantle, the Gutenberg discontinuity is mantle-outer core (where liquid stops S-waves), and the Lehmann discontinuity is outer core-inner core.

Step-by-Step Solution

1

Identify intra-crustal zoning features

The Conrad discontinuity lies within the crust, separating the granitic upper crust (

SIAL

) from the basaltic lower crust (

SIMA

).

It represents a density contrast within continental crustal material.

2

Identify the crust-mantle boundary

The Mohorovičić discontinuity separates continental and oceanic crust from the denser peridotite mantle below.

Seismic wave velocities increase markedly across this compositional boundary.

3

Identify the mantle-core transition

The Gutenberg discontinuity occurs at

2,900\text{ km}

depth, marking the change from the solid mantle to the liquid outer core where S-waves cannot propagate.

Shear waves cannot pass through liquid media.

4

Identify the inner-outer core boundary

The Lehmann discontinuity separates the liquid iron-nickel outer core from the solid inner core at a depth of roughly

5,150\text{ km}

.

Higher pressure at the center forces iron and nickel into a solid metallic crystal structure despite high temperatures.

Key Concept

Internal Structure of the Earth and Seismic Discontinuities

Question 12371Question →

When travelling across Nigeria along a direct south-to-north transect from Port Harcourt to Maiduguri, which vegetation belt is encountered immediately north of the Guinea Savanna before reaching the extreme northern Sahel margin?

Sahel Savanna

Sudan Savanna

Tropical Rainforest

Montane Vegetation

Show answer & explanation

Answer: Sudan Savanna

Answer

Sudan Savanna

Nigeria's vegetation distribution follows a distinct south-to-north zonal pattern driven by decreasing annual rainfall. Moving inland from the coast toward Lake Chad, the sequence passes from mangrove swamps and rainforests through the Guinea Savanna into the Sudan Savanna, before finally terminating in the semi-arid Sahel Savanna. Thus, the Sudan Savanna lies immediately north of the Guinea Savanna.

Step-by-Step Solution

1

Identify the geographical direction of the transect and the primary climatic control.

The transect moves from south to north, along which total annual rainfall steadily decreases and the dry season lengthens.

Vegetation distribution in Nigeria is primarily governed by the latitudinal gradient of rainfall controlled by the Inter-Tropical Discontinuity (ITD).

2

Trace the sequential latitudinal zonation of vegetation belts in Nigeria from south to north.

The sequence is: Mangrove/Saltwater Swamp Forest → Freshwater Swamp Forest → Tropical Rainforest → Guinea Savanna (Derived and Southern/Northern Guinea) → Sudan Savanna → Sahel Savanna.

Establishing the complete zonal sequence allows accurate identification of neighboring zones.

3

Determine the zone located directly north of the Guinea Savanna.

The Sudan Savanna is the vegetation belt positioned immediately north of the Guinea Savanna belt.

The Sudan Savanna forms a broad transitional savanna belt between the wetter Guinea Savanna to its south and the semi-arid Sahel Savanna to its north.

Key Concept

Latitudinal zonation of Nigerian vegetation belts driven by rainfall gradient

Question 12372Question →

Mass wasting processes exhibit varying rates of downslope movement based on slope angle, moisture saturation, and particle mechanics. Arrange the following mass wasting processes in sequence according to their typical velocity of movement, starting from the slowest process to the fastest process.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence from slowest to fastest rate of movement is: Soil creep driven by freeze-thaw cycles, followed by Solifluction over permafrost, then Debris flow surging down a channel, and finally Rock avalanche riding on air cushion.

Mass wasting processes are categorized along a velocity spectrum. Soil creep operates imperceptibly (< 1 cm/year) as individual soil particles shift downslope during expansion-contraction cycles. Solifluction is slightly faster (cm to m/year) as saturated topsoil flows over frozen subsoil. Debris flows move rapidly (m/s) as liquid-saturated materials surge through steep channels. Rock avalanches are catastrophic and move fastest (> 50 m/s) because air trapped beneath the plunging rock mass drastically reduces friction.

Step-by-Step Solution

1

Identify the slowest mass wasting process governed by microscopic particle shifting.

Soil creep operates imperceptibly (rates < 1 cm/year) due to alternating freeze-thaw or wet-dry particle expansion and contraction.

It involves dry-to-moist diffuse mantle displacement across low-to-moderate gradients.

2

Identify the slow viscous flow process restricted to saturated surface layers.

Solifluction moves at rates of several centimeters to meters per year as water-logged soil flows over impermeable permafrost or clay hardpans.

High pore-water pressure reduces shear strength, but movement remains constrained by ground thermal conditions.

3

Identify the rapid fluid-like channelized flow mass movement.

Debris flows travel rapidly down steep channels at velocities from 1 m/s to over 10 m/s following intense precipitation events.

Liquefaction and fluid displacement transform the material into a fast-moving slurry.

4

Identify the extremely rapid high-energy slope collapse event.

Rock avalanches move at extreme velocities exceeding 50 to 100 meters per second.

Catastrophic rock slope failure generates air entrapment beneath the sliding debris mass, drastically eliminating friction.

Key Concept

Classification of mass wasting processes based on movement mechanics and velocity spectrum

Question 12373Question →

In the regional pedological zonation of Nigeria, which soil group is predominantly found within the humid tropical rainforest belt of the south and is heavily leached due to high rainfall?

Ferrallitic soils

Regosols

Ferruginous tropical soils

Hydromorphic soils

Show answer & explanation

Answer: Ferrallitic soils

Answer

Ferrallitic soils are the main soil group occupying the humid tropical rainforest zone of Southern Nigeria, characterized by heavy leaching resulting from high annual rainfall.

Ferrallitic soils (also known as latosols) are the dominant zonal soil type of the humid rainforest belt of Southern Nigeria. Abundant annual rainfall promotes deep chemical weathering and extensive leaching (ferrallitization), leaving behind acidic soils rich in iron and aluminum oxides.

Step-by-Step Solution

1

Identify the geographical region and climate zone specified in the stem

The target area is Southern Nigeria, which is defined by high annual rainfall and humid tropical rainforest vegetation.

Soil formation and geographical distribution in Nigeria are heavily influenced by latitudinal climatic gradients.

2

Match the environmental conditions to the corresponding Nigerian zonal soil type

Continuous high rainfall in the southern forest zone causes intense leaching of soluble bases, producing Ferrallitic soils (latosols).

Ferrallitic soils form under intense leaching conditions where silica and bases are washed away, leaving residual iron and aluminum oxides.

Key Concept

Ferrallitic soil distribution in Southern Nigeria

Question 12374Question →

Drainage networks develop in response to specific rock structures and surface slopes. How do the following drainage pattern types match with their primary geological controls?

Click a left item, then click its matching right item

Show answer & explanation

Answer

Dendritic pattern pairs with uniform lithology and flat-lying strata; Radial pattern pairs with volcanic domes or central peaks; Trellis pattern pairs with alternating bands of hard and soft folded rocks; Centripetal pattern pairs with inward-sloping interior basins.

Each drainage pattern reflects specific surface geology: dendritic networks form on uniform rocks with equal erosion resistance, radial networks diverge outward from central domes, trellis networks align with alternating bands of folded rocks, and centripetal networks converge inward toward central basins.

Step-by-Step Solution

1

Identify the characteristic geological setting for a dendritic pattern

Dendritic drainage exhibits random branching on homogeneous rock types.

Equal resistance of underlying rock allows streams to flow in any direction without structural restriction.

2

Identify the structural control of a radial pattern

Radial drainage radiates outward from elevated peaks or domes.

High central relief forces water to flow downhill in all outward directions.

3

Identify the structural control of a trellis pattern

Trellis drainage follows alternating weak and resistant folded strata.

Main streams carve long parallel valleys in soft strata while short tributaries join at right angles across hard ridges.

4

Identify the structural control of a centripetal pattern

Centripetal drainage converges inward into a central depression.

Topography slopes downward toward a common interior low point.

Key Concept

Geological Controls on Drainage Patterns

Question 12375Question →

In the seasonally flooded floodplains and low-lying river valleys of Nigeria (commonly referred to as Fadama lands), intensive dry-season agriculture is widely practiced. Which soil type dominates these riverine environments, and what key characteristic accounts for its high agricultural productivity?

Hydromorphic soils, characterized by fine alluvial silt deposition and high organic matter content under poorly drained conditions

Ferrallitic soils, characterized by deep leaching of plant nutrients and heavy accumulation of iron and aluminum oxides

Regosols, characterized by loose, coarse sandy grains with minimal organic matter deposited by desert winds

Ferruginous tropical soils, characterized by a hardened surface ironstone pan formed over basement complex rocks

Show answer & explanation

Answer: Hydromorphic soils, characterized by fine alluvial silt deposition and high organic matter content under poorly drained conditions

Answer

Hydromorphic soils, characterized by fine alluvial silt deposition and high organic matter content under poorly drained conditions

Hydromorphic (alluvial) soils dominate Nigerian floodplains and Fadama areas along major rivers and deltaic zones. Seasonal overflow deposits fertile fine silt, clay, and organic material under waterlogged conditions, creating nutrient-rich soil with high water-retention capacity ideal for intensive dry-season cultivation.

Step-by-Step Solution

1

Identify the geographical setting described in the question stem

The setting is river valleys, low-lying floodplains, and Fadama zones along major Nigerian rivers like the Niger and Benue.

Topographic position and drainage conditions determine pedogenic processes.

2

Associate the geographical environment with its corresponding soil group

Seasonally inundated or waterlogged valley floors foster hydromorphic (alluvial) soil formation.

Excess water leads to gleying and continuous deposition of fine river sediment (silt and clay) along with organic debris.

3

Evaluate the primary physical property supporting dry-season farming

High silt content, good water retention, and rich organic deposits provide high natural fertility without rapid drying.

These characteristics make Fadama lands highly productive for vegetable and rice cultivation.

Key Concept

Hydromorphic (alluvial) soil distribution and characteristics in Nigerian river floodplains

Estimated Time:1m 0s

Question 12376Question →

On a topographical map drawn to a scale of $1 : 25,000$ , Point P is situated at a trigonometric station with an elevation of $520\text{ m}$ , while Point Q lies at a stream confluence at an elevation of $370\text{ m}$ . The measured straight-line distance between Point P and Point Q on the map is $15\text{ cm}$ . What is the slope gradient between Point P and Point Q, expressed as the denominator $N$ in the ratio $1 \text{ in } N$ ?

Show answer & explanation

Answer: 25

Answer

The denominator

N

of the slope gradient ratio (

1 \text{ in } N

) is 25.

The Vertical Interval (VI) between Point P and Point Q is

520\text{ m} - 370\text{ m} = 150\text{ m}

. Using the map scale of

1 : 25,000

, the Horizontal Equivalent (HE) is

15\text{ cm} \times 25,000 = 375,000\text{ cm} = 3,750\text{ m}

. Dividing the VI by the HE gives

\frac{150}{3,750} = \frac{1}{25}

. Therefore, the gradient expressed as a ratio is

1 \text{ in } 25

, and the denominator

N

is 25.

Step-by-Step Solution

1

Determine the Vertical Interval (VI)

\text{VI} = 520\text{ m} - 370\text{ m} = 150\text{ m}

Vertical Interval is the difference in elevation between the higher and lower points.

2

Calculate the Horizontal Equivalent (HE) in ground units (meters)

\text{HE} = 15\text{ cm} \times 25,000 = 375,000\text{ cm} = 3,750\text{ m}

Horizontal Equivalent is obtained by converting the measured map distance to actual ground distance using the representative fraction scale.

3

Compute the Gradient Ratio

\text{Gradient} = \frac{\text{VI}}{\text{HE}} = \frac{150\text{ m}}{3,750\text{ m}} = \frac{1}{25}

Gradient is the ratio of Vertical Interval to Horizontal Equivalent, both expressed in identical units.

Key Concept

Slope and Gradient Calculation using Representative Fraction Map Scale

Estimated Time:1m 30s

Question 12377Question →

Match each specified drainage pattern with its underlying geological control or characteristic landform surface.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Trellis drainage pattern matches with folded strata containing alternating hard and soft rocks; Rectangular pattern matches with faulted and jointed bedrock; Radial pattern matches with outward flow from a central dome or volcano; Dendritic pattern matches with tree-like branching on uniform rock resistance.

Each pattern corresponds directly to its bedrock control: Trellis requires alternating soft/hard folded belts, Rectangular follows structural joints and faults, Radial descends from a central highland dome or cone, and Dendritic branches randomly over uniform lithology.

Step-by-Step Solution

1

Analyze Trellis Drainage Pattern

Trellis drainage features long main streams parallel to strike valleys with short tributaries entering at right angles, characteristic of folded, tilted strata.

Differential erosion along parallel belts of soft and hard rock forces tributaries into strike valleys.

2

Analyze Rectangular Drainage Pattern

Rectangular drainage is characterized by right-angled bends in main streams and tributaries along lineaments.

Bedrock fractures, joint systems, and faults direct the line of weakest resistance for stream incision.

3

Analyze Radial Drainage Pattern

Radial drainage streams flow in all cardinal directions downward from a central peak.

Topographic highs like domes and volcanic summits direct water outward along radial slopes.

4

Analyze Dendritic Drainage Pattern

Dendritic drainage exhibits a random branching tree-like structure without structural alignment.

Uniform rock resistance (lithology) allows equal erosion in all directions.

Key Concept

Geological Controls on Drainage Network Patterns

Question 12378Question →

On a topographical map, the vertical difference between two points, X and Y, is $100\text{ m}$ . If the horizontal distance separating them on the ground is $2\text{ km}$ , what is the gradient of the slope between Point X and Point Y?

1 in 20

1 in 2

1 in 200

20 to 1

Show answer & explanation

Answer: 1 in 20

Answer

The gradient between Point X and Point Y is 1 in 20.

The vertical interval is

100\text{ m}

and the horizontal equivalent is

2\text{ km}

. Converting

2\text{ km}

into metres gives

2,000\text{ m}

. Applying the slope gradient formula

\frac{\text{VI}}{\text{HE}} = \frac{100\text{ m}}{2,000\text{ m}} = \frac{1}{20}

gives a gradient of

1\text{ in } 20

.

Step-by-Step Solution

1

Identify the Vertical Interval (VI) and Horizontal Equivalent (HE)

\text{VI} = 100\text{ m}

and

\text{HE} = 2\text{ km}

Gradient calculation requires both vertical elevation change and horizontal ground distance.

2

Convert Horizontal Equivalent into metres so both measurements share identical units

\text{HE} = 2\text{ km} \times 1,000 = 2,000\text{ m}

Gradient is a unitless ratio, requiring numerator and denominator to be in the same unit.

3

Calculate gradient using the formula

\text{Gradient} = \frac{\text{VI}}{\text{HE}}

\text{Gradient} = \frac{100\text{ m}}{2,000\text{ m}} = \frac{1}{20}

Simplifying the fraction yields a ratio of

1\text{ in } 20

.

Key Concept

Slope Gradient Calculation on Topographical Maps

Question 12379Question →

Arrange the following structural layers of the Earth in sequence from the outermost surface layer down to the Earth's center.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct order from the Earth's surface descending to its center is Sial, Sima, Asthenosphere, Lower Mantle, and Barysphere.

The structural layers of the Earth arranged from the outermost surface to the center follow a progression based on increasing density and depth: Sial (upper continental crust), Sima (lower crust/oceanic basin floor), Asthenosphere (ductile upper mantle zone), Lower Mantle (solid silicate interior), and Barysphere (innermost metallic core).

Step-by-Step Solution

1

Identify the outermost crustal layers based on composition and density.

Sial forms the upper continental crust, lying directly above the denser Sima layer.

Sial has a lower average density (

2.7\text{ g/cm}^3

) than Sima (

3.0\text{ g/cm}^3

), allowing it to float on top of the sima layer.

2

Determine the position of mantle layers relative to the crust.

The semi-fluid Asthenosphere lies in the upper mantle beneath the crust, followed by the rigid Lower Mantle below it.

The lithosphere (crust and uppermost solid mantle) rests upon the ductile asthenosphere, which transitions into the deeper, solid lower mantle.

3

Locate the central core region of the Earth.

The Barysphere occupies the innermost portion of the Earth.

The metallic core (Barysphere) possesses the highest density (

10.0\text{--}13.0\text{ g/cm}^3

) and occupies the central interior of the planet.

Key Concept

Concentric internal layering of the Earth from surface to center

Question 12380Question →

Match each topographic map slope calculation scenario on the left with its corresponding calculated gradient representation on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct pairings are: (1) A vertical rise of 50 m across 4 cm on a 1:25,000 map matches 1 in 20 (5.0%); (2) An elevation change from 120 m to 320 m over 5 cm on a 1:50,000 map matches 1 in 12.5 (8.0%); (3) A rise of 150 m over 6 cm on a 1:25,000 map matches 1 in 10 (10.0%); (4) Crossing 4 contour intervals of 20 m across 4 cm at 1:100,000 scale matches 1 in 50 (2.0%).

Each scenario is accurately paired by converting the map distance to actual ground distance in meters using the given scale, determining the vertical interval, and computing the gradient as a ratio (1 in N) and percentage.

Step-by-Step Solution

1

Convert the map distance for each scenario into the ground horizontal distance (Horizontal Equivalent, HE) in meters using the designated map scale.

Scenario 1:

4\text{ cm} \times 25,000 / 100 = 1,000\text{ m}

. Scenario 2:

5\text{ cm} \times 50,000 / 100 = 2,500\text{ m}

. Scenario 3:

6\text{ cm} \times 25,000 / 100 = 1,500\text{ m}

. Scenario 4:

4\text{ cm} \times 100,000 / 100 = 4,000\text{ m}

.

Map scale Representative Fractions convert map measurements to real ground horizontal distances, which must be expressed in meters to match the unit of Vertical Interval.

2

Calculate the total height difference (Vertical Interval, VI) in meters for each terrain scenario.

Scenario 1:

\text{VI} = 50\text{ m}

. Scenario 2:

\text{VI} = 320\text{ m} - 120\text{ m} = 200\text{ m}

. Scenario 3:

\text{VI} = 150\text{ m}

. Scenario 4:

\text{VI} = 4 \text{ intervals} \times 20\text{ m} = 80\text{ m}

.

Vertical Interval represents the net vertical relief difference between the start and end points of the transect.

3

Compute the gradient ratio (VI / HE) and express it both as a simple ratio (1 in N) and as a percentage slope.

Scenario 1:

\frac{50}{1,000} = \frac{1}{20} \rightarrow 1 \text{ in } 20

(

5.0\%

). Scenario 2:

\frac{200}{2,500} = \frac{1}{12.5} \rightarrow 1 \text{ in } 12.5

(

8.0\%

). Scenario 3:

\frac{150}{1,500} = \frac{1}{10} \rightarrow 1 \text{ in } 10

(

10.0\%

). Scenario 4:

\frac{80}{4,000} = \frac{1}{50} \rightarrow 1 \text{ in } 50

(

2.0\%

).

Gradient formula is

\text{Gradient} = \frac{\text{Vertical Interval (VI)}}{\text{Horizontal Equivalent (HE)}}

.

Key Concept

Slope and Gradient Calculation from Topographical Maps

Estimated Time:3m 0s

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