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Kerala Plus Two Geology practice questions

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Question 1Physical Geology and Earth Processes

Which layer of the Earth lies directly beneath the crust and is composed mainly of peridotite rock?

  1. The mantle Correct answer.
  2. The outer core
  3. The lithosphere
  4. The inner core

Explanation

The mantle is the thick silicate layer between the crust and the core, and its dominant rock type is peridotite, rich in olivine and pyroxene. The core is metallic (iron-nickel), and the lithosphere is a rigid outer shell that includes the crust plus the uppermost mantle.

Question 2Physical Geology and Earth Processes

A seismic station records P-waves but no S-waves from a distant earthquake. What does this most directly indicate about the material the waves passed through?

  1. A liquid layer blocked the S-waves Correct answer.
  2. P-waves travel more slowly than S-waves
  3. The station was too close to the epicentre
  4. The earthquake was too shallow to generate S-waves

Explanation

S-waves are shear waves and cannot propagate through fluids, so their absence beyond about 103 degrees from the epicentre reveals a liquid outer core. P-waves are compressional and pass through both solids and liquids, which is why they still arrive.

Question 3Physical Geology and Earth Processes

Which type of plate boundary is marked by the Mid-Atlantic Ridge?

  1. Transform boundary
  2. Passive continental margin
  3. Divergent boundary Correct answer.
  4. Convergent boundary

Explanation

The Mid-Atlantic Ridge is a spreading centre where the American and Eurasian/African plates move apart and new basaltic crust forms. This makes it a classic divergent (constructive) boundary, not a collision or strike-slip zone.

Question 4Physical Geology and Earth Processes

Oceanic lithosphere subducts beneath continental lithosphere mainly because oceanic lithosphere is:

  1. More felsic in composition
  2. Denser and thinner Correct answer.
  3. Older and more buoyant
  4. Hotter and thicker

Explanation

Oceanic crust is basaltic (mafic) and, together with its thin lithospheric mantle, becomes denser as it cools, so it sinks at convergent margins. Continental crust is thicker and more buoyant (felsic), so it resists subduction.

Question 5Physical Geology and Earth Processes

Which mineral is the most abundant primary constituent of granite?

  1. Calcite
  2. Quartz Correct answer.
  3. Olivine
  4. Gypsum

Explanation

Granite is a felsic plutonic rock dominated by quartz, alkali feldspar and plagioclase, with quartz typically making up a large fraction of the mode. Olivine is mafic, calcite is a carbonate, and gypsum is an evaporite mineral.

Question 6Physical Geology and Earth Processes

A basalt sample shows a fine-grained groundmass with scattered large olivine crystals. Which term best describes this texture?

  1. Phaneritic
  2. Pegmatitic
  3. Vesicular
  4. Porphyritic Correct answer.

Explanation

A porphyritic texture consists of larger crystals (phenocrysts) set in a finer groundmass, recording two stages of cooling. Phaneritic and pegmatitic textures are coarse throughout, and vesicular refers to gas cavities rather than crystal-size contrast.

Question 7Physical Geology and Earth Processes

Which sequence correctly shows increasing metamorphic grade for a pelitic rock?

  1. Slate, phyllite, schist, gneiss Correct answer.
  2. Schist, slate, gneiss, phyllite
  3. Phyllite, gneiss, slate, schist
  4. Gneiss, schist, phyllite, slate

Explanation

Increasing temperature and pressure progressively coarsen the fabric of a clay-rich rock: slate has a strong slaty cleavage, phyllite a silky sheen, schist visible micas, and gneiss distinct compositional banding. The other sequences place high-grade rocks before low-grade ones.

Question 8Physical Geology and Earth Processes

Which sedimentary structure indicates that a bed has been overturned after deposition?

  1. Mud cracks at the base of the bed
  2. Graded bedding that coarsens upward Correct answer.
  3. Ripple marks with rounded crests
  4. Cross-bedding dipping in the current direction

Explanation

Normal graded bedding fines upward because the coarsest grains settle first; an upward-coarsening pattern means the bed is inverted. Cross-bedding, ripples and mud cracks are common in normal beds but do not by themselves reveal overturning.

Question 9Physical Geology and Earth Processes

The principle of superposition states that in an undisturbed sequence of sedimentary rocks:

  1. The thickest layers lie at the bottom
  2. The coarsest layers lie at the bottom
  3. The most fossiliferous layers lie at the bottom
  4. The oldest layers lie at the bottom Correct answer.

Explanation

Superposition concerns relative age: each layer was deposited on the one below, so the lowest bed is the oldest in an undeformed succession. Grain size, fossil content and bed thickness vary independently and do not follow a fixed vertical rule.

Question 10Physical Geology and Earth Processes

A fault plane dips 60 degrees and the hanging wall has moved down relative to the footwall. What type of fault is this?

  1. Thrust fault
  2. Strike-slip fault
  3. Reverse fault
  4. Normal fault Correct answer.

Explanation

In a normal fault the hanging wall moves down along a steeply dipping plane, reflecting extension. Reverse and thrust faults show hanging-wall uplift, and strike-slip faults involve horizontal displacement along the fault.

Question 11Physical Geology and Earth Processes

In an anticline, what is the relationship between the dip direction of the two limbs and the age of the rocks near the axis?

  1. Limbs dip toward the axis and the oldest rocks lie near the axis
  2. Limbs dip away from the axis and the youngest rocks lie near the axis
  3. Limbs dip toward the axis and the youngest rocks lie near the axis
  4. Limbs dip away from the axis and the oldest rocks lie near the axis Correct answer.

Explanation

An anticline is an upward-arching fold, so its limbs dip outward from the crest and erosion exposes the oldest strata along the core. A syncline is the downward trough with limbs dipping inward and youngest rocks at the axis.

Question 12Physical Geology and Earth Processes

Which weathering process is an example of hydrolysis acting on feldspar?

  1. Conversion of feldspar to clay minerals Correct answer.
  2. Dissolution of halite in rainwater
  3. Abrasion of bedrock by wind-blown sand
  4. Frost shattering of a jointed rock face

Explanation

Hydrolysis involves reaction between minerals and water, converting feldspar into clay minerals such as kaolinite while releasing ions into solution. Frost shattering and abrasion are mechanical processes, and halite dissolution is simple solution.

Question 13Physical Geology and Earth Processes

Which soil horizon is typically the zone of accumulation of clay, iron oxides and other leached material?

  1. The C horizon
  2. The O horizon
  3. The B horizon Correct answer.
  4. The A horizon

Explanation

The B horizon is the subsoil zone where illuviation deposits clay, iron and aluminium oxides washed down from above. The O horizon is organic litter, the A horizon is the eluvial topsoil, and the C horizon is weathered parent material.

Question 14Physical Geology and Earth Processes

A stream's discharge increases downstream while its gradient decreases. What typically happens to the sediment it carries?

  1. The load becomes uniformly gravel-sized
  2. The load disappears entirely because the gradient is low
  3. The load becomes coarser and dominated by boulders
  4. The load becomes finer and more suspended material appears Correct answer.

Explanation

Downstream, decreasing gradient reduces competence so coarse bedload is deposited, while increased discharge and finer abrasion products keep more silt and clay in suspension. The result is a downstream fining of the load, not its disappearance.

Question 15Physical Geology and Earth Processes

Which feature forms where a river leaves a steep mountain front and enters a flat plain?

  1. A point bar
  2. A delta
  3. A meander scar
  4. An alluvial fan Correct answer.

Explanation

An alluvial fan is a fan-shaped deposit built where a confined channel abruptly loses gradient and spreads its coarse load across a plain. Deltas form where rivers enter standing water, and meander scars and point bars belong to the floodplain of a meandering channel.

Question 16Physical Geology and Earth Processes

Which agent is responsible for the formation of a U-shaped valley with truncated spurs?

  1. River meandering
  2. Glacial erosion Correct answer.
  3. Wind deflation
  4. Wave action

Explanation

Glaciers erode their beds and walls by abrasion and plucking, widening and deepening pre-existing valleys into a U-shaped profile and truncating interlocking spurs. Rivers cut narrow V-shaped valleys, wind deflates loose material, and waves produce shore platforms.

Question 17Physical Geology and Earth Processes

A cirque, an arête and a horn are landforms produced by which process?

  1. Erosion by valley and mountain glaciers Correct answer.
  2. Deposition by continental ice sheets
  3. Deposition by wind in a desert basin
  4. Chemical weathering in a tropical climate

Explanation

Cirques are armchair-shaped hollows carved at glacier heads, arêtes are sharp ridges between two cirques, and horns are pyramidal peaks where three or more cirques intersect. All three are erosional features of alpine glaciation.

Question 18Physical Geology and Earth Processes

Which coastal feature is built by deposition rather than erosion?

  1. A sea cliff
  2. A wave-cut platform
  3. A sea arch
  4. A spit Correct answer.

Explanation

A spit is a ridge of sand or shingle deposited by longshore drift where the coastline changes direction. Sea arches, wave-cut platforms and sea cliffs are all products of wave erosion of bedrock.

Question 19Physical Geology and Earth Processes

What is the primary cause of a tsunami generated by an offshore earthquake?

  1. Sudden vertical displacement of the sea floor Correct answer.
  2. Rapid heating of seawater at the epicentre
  3. Melting of submarine gas hydrates
  4. Strong surface winds accompanying the quake

Explanation

A tsunami forms when an earthquake abruptly uplifts or drops a large area of the sea floor, displacing the entire water column. Wind produces ordinary waves, and heating or hydrate melting does not displace the water column coherently.

Question 20Physical Geology and Earth Processes

On the Richter scale, an increase of two magnitude units corresponds to what change in the amplitude recorded by a seismograph?

  1. A thousandfold increase
  2. A hundredfold increase Correct answer.
  3. A twofold increase
  4. A tenfold increase

Explanation

The Richter scale is logarithmic, with each whole unit representing a tenfold increase in wave amplitude, so two units correspond to 10 x 10 = 100 times the amplitude. The associated energy release rises by roughly 32 times per unit.

Question 21Physical Geology and Earth Processes

Which volcano type is characteristically built of alternating lava flows and pyroclastic layers and has steep slopes?

  1. Composite (stratovolcano) Correct answer.
  2. Lava dome
  3. Shield volcano
  4. Cinder cone

Explanation

Stratovolcanoes form from alternating explosive pyroclastic eruptions and viscous lava flows, producing steep, layered cones such as Fuji. Shield volcanoes are broad and gentle, cinder cones are small and built of scoria, and lava domes are mounds of viscous lava.

Question 22Physical Geology and Earth Processes

Which magma composition is most likely to produce a highly explosive eruption?

  1. Low-silica basaltic magma
  2. Magma with very low gas content
  3. Magma erupted under deep water
  4. High-silica rhyolitic magma Correct answer.

Explanation

High-silica magma is highly viscous and traps dissolved gases until pressure builds and releases explosively. Basaltic magma is fluid and degasses easily, giving effusive flows, and low gas content reduces explosivity.

Question 23Physical Geology and Earth Processes

Which process is the main way groundwater enlarges a cave in limestone?

  1. Abrasion by wind-blown sand
  2. Oxidation of iron-bearing minerals
  3. Dissolution of calcite by slightly acidic water Correct answer.
  4. Freezing and thawing of water in joints

Explanation

Rainwater absorbs carbon dioxide and forms weak carbonic acid, which dissolves calcite along joints and bedding planes to enlarge conduits. Frost wedging and wind abrasion act mechanically, and iron oxidation affects mafic minerals rather than dissolving limestone.

Question 24Physical Geology and Earth Processes

Which karst feature is a vertical shaft or funnel-shaped depression formed by solution on a limestone surface?

  1. A flowstone terrace
  2. A speleothem
  3. A stalactite
  4. A sinkhole Correct answer.

Explanation

A sinkhole (doline) is a surface depression produced by solution of limestone and, sometimes, collapse of an underlying cavity. Stalactites and flowstone are depositional cave features, and speleothem is a general term for such deposits.

Question 25Physical Geology and Earth Processes

Which factor most strongly controls the angle of repose of a dry sand slope?

  1. Colour of the grains
  2. Mineral hardness
  3. Age of the deposit
  4. Grain size and shape Correct answer.

Explanation

The angle of repose reflects the balance between gravity and intergranular friction, so angular and coarser grains usually stand steeper than rounded, finer ones. Colour, age and hardness do not directly set the slope angle.

Question 26Physical Geology and Earth Processes

Which mineral property is defined as the tendency of a mineral to break along planes of weak atomic bonding, producing flat, reflective surfaces?

  1. Tenacity
  2. Cleavage Correct answer.
  3. Streak
  4. Fracture

Explanation

Cleavage is the repeated breaking of a mineral along planar surfaces controlled by zones of weaker chemical bonding in its crystal lattice, so the broken surfaces are flat and shiny. Fracture describes irregular breakage with no preferred plane, tenacity describes resistance to breaking or bending, and streak is the colour of powdered mineral.

Question 27Physical Geology and Earth Processes

A magma body cools slowly at depth, allowing crystals to grow large, and the residual melt is later quenched quickly at the margin of the intrusion. Which texture would you expect at the chilled margin?

  1. Coarse-grained equigranular texture
  2. Foliated texture
  3. Fine-grained or glassy texture Correct answer.
  4. Porphyroblastic texture

Explanation

Rapid cooling at a chilled margin leaves little time for crystal growth, so the rock is fine-grained or glassy. Slow cooling at depth is what produces coarse crystals, and porphyroblastic and foliated textures are metamorphic rather than igneous.

Question 28Physical Geology and Earth Processes

A rock sample contains abundant olivine and pyroxene with very little quartz or feldspar. Based on this mineral assemblage, how should the rock be classified chemically?

  1. Intermediate, because two mafic minerals are present
  2. Felsic, because it is rich in dark minerals
  3. Ultramafic, because ferromagnesian minerals dominate Correct answer.
  4. Alkaline, because olivine indicates high sodium content

Explanation

Silica content controls the felsic–mafic–ultramafic classification, and a rock dominated by olivine and pyroxene with almost no quartz or feldspar is silica-poor and therefore ultramafic. Dark colour and abundance of ferromagnesian minerals both point toward the mafic to ultramafic end of the series.

Question 29Physical Geology and Earth Processes

A sediment pile consists of gravel at the base, sand above it and clay at the top, with each layer internally showing normal grading. Which statement best explains this arrangement?

  1. The pile was overturned by folding after deposition, reversing the original order
  2. The pile records three separate episodes of decreasing transport energy, coarsest first Correct answer.
  3. The whole pile was deposited by a single turbidity current that waned in energy
  4. The pile accumulated on a beach where wave energy increased over time

Explanation

In an undisturbed sequence the coarsest sediment lies lowest, so gravel followed by sand and clay records successive depositional episodes of declining energy, each layer being finer upward within itself. An overturning event would have to be demonstrated independently, and increasing wave energy would produce the reverse order.

Question 30Physical Geology and Earth Processes

A confined sandstone aquifer dips gently and is overlain by impermeable shale, with its recharge area at a higher elevation and its discharge at a lower spring. Which condition is required for the well to flow without pumping?

  1. The aquifer must be unconfined along its entire length
  2. The shale cap must be more permeable than the sandstone
  3. The potentiometric surface must rise above the level of the well head Correct answer.
  4. The water table must lie below the top of the sandstone

Explanation

An artesian well flows unaided only when the confined aquifer is fully saturated and its potentiometric surface stands above the well head, so the pressure drives water upward. If the potentiometric surface lies below the well head, water must be pumped, and an unconfined aquifer has no confining layer to sustain such pressure.

Question 31Mineralogy

Which silicate mineral group is characterized by isolated SiO4 tetrahedra that are not linked to each other?

  1. Inosilicates
  2. Phyllosilicates
  3. Tectosilicates
  4. Nesosilicates Correct answer.

Explanation

Nesosilicates, also called orthosilicates, have isolated SiO4 tetrahedra held together only by cations. In contrast, inosilicates form chains, phyllosilicates form sheets, and tectosilicates form three-dimensional frameworks. The isolated tetrahedron structure gives nesosilicates relatively high density and hardness.

Question 32Mineralogy

The property of a mineral that describes its resistance to scratching is called:

  1. Hardness Correct answer.
  2. Cleavage
  3. Tenacity
  4. Specific gravity

Explanation

Hardness is the resistance of a mineral surface to scratching, commonly ranked on the Mohs scale. Cleavage describes breaking along planar surfaces, tenacity describes resistance to breaking or deformation, and specific gravity is a density ratio. Hardness is one of the most useful diagnostic properties in hand specimen identification.

Question 33Mineralogy

Which mineral is the most common member of the feldspar group in the Earth's crust?

  1. Quartz
  2. Calcite
  3. Plagioclase feldspar Correct answer.
  4. Muscovite

Explanation

Plagioclase feldspar is the most abundant feldspar and one of the most common minerals in the crust. Quartz is common but is not a feldspar. Muscovite is a mica, and calcite is a carbonate. Feldspars are framework silicates and are essential in classifying igneous rocks.

Question 34Mineralogy

Which of the following minerals is a common carbonate mineral that reacts visibly with dilute hydrochloric acid?

  1. Talc
  2. Halite
  3. Gypsum
  4. Calcite Correct answer.

Explanation

Calcite (CaCO3) effervesces with dilute HCl because it releases carbon dioxide gas. Halite is a chloride, gypsum is a sulfate, and talc is a silicate; none gives the same vigorous reaction. This simple field test distinguishes calcite from many similar-looking light-colored minerals.

Question 35Mineralogy

In the Mohs hardness scale, which mineral has a hardness of 7 and is commonly used as a reference for scratching glass?

  1. Orthoclase
  2. Quartz Correct answer.
  3. Apatite
  4. Topaz

Explanation

Quartz has a Mohs hardness of 7, so it scratches glass (hardness about 5.5) but is scratched by topaz (8). Apatite is 5, orthoclase is 6, and topaz is 8. Quartz is therefore a practical field reference for hardness 7.

Question 36Mineralogy

Which mineral shows perfect cleavage in one direction, giving thin flexible sheets?

  1. Muscovite Correct answer.
  2. Garnet
  3. Magnetite
  4. Quartz

Explanation

Muscovite is a mica with a sheet silicate structure; its perfect basal cleavage produces thin, flexible, elastic sheets. Quartz lacks cleavage and shows conchoidal fracture, garnet shows no cleavage, and magnetite breaks unevenly. The sheet cleavage of mica reflects its layered atomic structure.

Question 37Mineralogy

Which of the following is a native element mineral?

  1. Hematite
  2. Galena
  3. Graphite Correct answer.
  4. Pyrite

Explanation

Graphite is composed of carbon only, making it a native element mineral. Pyrite is a sulfide, hematite is an oxide, and galena is a sulfide. Native elements occur in nature in uncombined form, such as gold, sulfur, diamond, and graphite.

Question 38Mineralogy

A mineral specimen is scratched by a copper coin but not by a fingernail. Its hardness is closest to:

  1. 7
  2. 3.5 Correct answer.
  3. 2.5
  4. 5.5

Explanation

A fingernail has a hardness of about 2.5 and a copper coin about 3.5. If the mineral is scratched by the coin but not by the fingernail, its hardness lies between these values, closest to 3.5. This field test narrows the identification to minerals of intermediate softness such as calcite.

Question 39Mineralogy

Which silicate mineral structure is present in olivine?

  1. Single-chain silicate
  2. Double-chain silicate
  3. Framework silicate
  4. Island silicate Correct answer.

Explanation

Olivine is a nesosilicate (island silicate) in which independent SiO4 tetrahedra are linked by magnesium and iron cations. This structure gives olivine high density and hardness and a green color. Pyroxene is single-chain, amphibole is double-chain, and feldspar is framework.

Question 40Mineralogy

Which mineral property is best described as the color of a mineral's powder when rubbed on unglazed porcelain?

  1. Diaphaneity
  2. Luster
  3. Streak Correct answer.
  4. Cleavage

Explanation

Streak is the color of the powdered mineral, obtained by rubbing it on a streak plate. It is often more reliable than the color of the whole specimen, especially for metallic minerals. Luster describes surface reflection, cleavage describes breakage planes, and diaphaneity describes light transmission.

Question 41Mineralogy

Which of the following minerals is a common evaporite mineral with a distinctive salty taste and cubic cleavage?

  1. Barite
  2. Halite Correct answer.
  3. Calcite
  4. Fluorite

Explanation

Halite (NaCl) is an evaporite mineral with cubic crystals and three directions of perfect cubic cleavage. It is soft, colorless to white, and has a salty taste. Calcite has rhombohedral cleavage, fluorite has octahedral cleavage, and barite is much denser and less common in evaporites.

Question 42Mineralogy

Which property of a mineral is directly related to its chemical composition and atomic structure?

  1. Color
  2. Hardness Correct answer.
  3. Luster
  4. Streak

Explanation

Hardness depends on the strength of chemical bonds and the density of atomic packing in the crystal structure. Color, luster, and streak can vary with impurities or surface effects. Hardness is therefore a fundamental diagnostic property tied to composition and structure.

Question 43Mineralogy

Which of the following minerals is a common sulfide ore mineral with a metallic luster and a greenish-black streak?

  1. Magnetite
  2. Galena
  3. Hematite
  4. Chalcopyrite Correct answer.

Explanation

Chalcopyrite (CuFeS2) is a brass-yellow sulfide with metallic luster and a greenish-black streak. Hematite and magnetite are oxides, and galena is a lead sulfide with a gray streak. Chalcopyrite is an important ore of copper.

Question 44Mineralogy

Which mineral is commonly known as 'fool's gold' because of its brassy yellow color and metallic luster?

  1. Pyrite Correct answer.
  2. Pyrrhotite
  3. Gold
  4. Chalcopyrite

Explanation

Pyrite (FeS2) is called fool's gold because its brassy yellow color and metallic luster resemble gold. Unlike gold, pyrite is harder, brittle, and forms cubic crystals. Chalcopyrite is also brassy but softer and less commonly mistaken for gold in hand specimens.

Question 45Mineralogy

A mineral has a vitreous luster, conchoidal fracture, and a hardness of 7. It is most likely:

  1. Quartz Correct answer.
  2. Gypsum
  3. Feldspar
  4. Calcite

Explanation

Quartz has a vitreous luster, conchoidal fracture, and a hardness of 7, and it lacks cleavage. Calcite is softer and has rhombohedral cleavage, feldspar has cleavage and a hardness of about 6, and gypsum is very soft with a hardness of 2. These combined properties point to quartz.

Question 46Mineralogy

Which of the following is a phyllosilicate mineral with a greasy feel and a hardness of 1?

  1. Serpentine
  2. Talc Correct answer.
  3. Chlorite
  4. Kaolinite

Explanation

Talc is a sheet silicate with a greasy or soapy feel and a Mohs hardness of 1, the softest mineral. Kaolinite is also soft but has a earthy feel and is not as greasy. Serpentine and chlorite are harder and have different lusters and colors.

Question 47Mineralogy

Which mineral is the main source of the element aluminum in commercial production?

  1. Corundum
  2. Feldspar
  3. Bauxite Correct answer.
  4. Mica

Explanation

Bauxite is a rock composed mainly of aluminum hydroxide minerals and is the principal ore of aluminum. Corundum is aluminum oxide but is too hard and rare for routine aluminum production. Feldspar and mica contain aluminum but are not economic aluminum ores.

Question 48Mineralogy

Which of the following best explains why diamond and graphite, both made of carbon, have such different physical properties?

  1. They contain different isotopes of carbon.
  2. They have different colors due to trace elements.
  3. They contain different amounts of impurities.
  4. They differ in the arrangement of carbon atoms in their crystal structures. Correct answer.

Explanation

Diamond and graphite are polymorphs of carbon: diamond has a three-dimensional covalent framework, while graphite has sheets of carbon atoms. This structural difference explains diamond's extreme hardness and graphite's softness and cleavage. Isotopes and impurities do not account for the major physical differences.

Question 49Mineralogy

Which of the following minerals would be expected to have the highest specific gravity?

  1. Feldspar
  2. Calcite
  3. Quartz
  4. Galena Correct answer.

Explanation

Galena (PbS) has a high specific gravity of about 7.5 because it contains heavy lead atoms. Quartz, feldspar, and calcite have specific gravities near 2.6 to 2.7. Specific gravity reflects the density of a mineral relative to water.

Question 50Mineralogy

Which of the following statements about the cleavage of a mineral is true?

  1. Cleavage planes are determined by planes of weak atomic bonding in the crystal structure. Correct answer.
  2. Cleavage is always present in every mineral.
  3. Cleavage is the same as fracture.
  4. Cleavage is the same as crystal form.

Explanation

Cleavage occurs along planes where atomic bonds are weakest, producing smooth planar surfaces. Crystal form describes the external shape of a crystal, fracture describes irregular breakage, and not all minerals have cleavage. Cleavage is therefore a structural property, not a shape or a type of fracture.