CUET PG 2026 Geology Question Paper with Solutions

Concept:

In crystallography, symmetry of a crystal is identified by the arrangement of faces, edges, points and symmetry elements.



Step 1: Understand the given condition.

The question says that a face on one side of the crystal is opposite to a point on the other side.

This means the two ends of the crystal are not similar.



Step 2: Identify the crystal character.

When the opposite ends of a crystal are dissimilar, the crystal is called hemimorphic.
\[ Face on one side and point on opposite side \Rightarrow Hemimorphic \]



Step 3: Eliminate other options.

Centrosymmetric crystals have a centre of symmetry.

Enantiomorphous crystals are mirror-related forms.

Non-centrosymmetric is a broad term, but the specific term for this condition is hemimorphic.
\[ \therefore Correct Answer is (D) \] Quick Tip: Hemimorphic crystals have dissimilar opposite ends.

Concept:

Crystal systems contain different numbers of crystal classes. The number of classes depends on symmetry elements present in the system.



Step 1: Recall number of classes.

The cubic crystal system has:
\[ 5 classes \]

The tetragonal crystal system has:
\[ 7 classes \]



Step 2: Compare the pair.

Since cubic has \(5\) classes and tetragonal has \(7\) classes, they do not have the same number of crystal classes.
\[ 5\neq 7 \]



Step 3: Final conclusion.

Therefore, the pair that does not have the same number of classes is:
\[ Cubic -- Tetragonal \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Cubic system has 5 crystal classes, while tetragonal system has 7 crystal classes.

Concept:

Zircon is an important mineral of the tetragonal crystal system. The symmetry of crystals is described by symmetry planes, axes and centre.



Step 1: Identify the crystal type.

Zircon belongs to the tetragonal system and is commonly used as an example of high symmetry tetragonal crystals.



Step 2: Symmetry elements.

Zircon type crystals are described as having:
\[ 5 planes \] \[ 5 axes \] \[ 1 centre of symmetry \]



Step 3: Select the matching option.

The option matching this description is:
\[ 5 planes, 5 axes and centre \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Zircon is a common example used for tetragonal crystal symmetry.

Concept:

Crystal faces develop during crystal growth. Their relative sizes are controlled by the growth conditions and degree of crystallization.



Step 1: Understand crystal faces.

A crystal face is a plane surface developed during crystal growth.



Step 2: Effect of crystallization.

If crystallization conditions are favourable, crystal faces develop properly. If conditions are not uniform, some faces may grow larger and others may remain smaller.



Step 3: Final conclusion.

Thus, the relative size and shape of a crystal face depends mainly on the degree of crystallization.
\[ \therefore Correct Answer is (B) \] Quick Tip: The development of crystal faces depends strongly on crystallization conditions.

Concept:

Feldspars are aluminosilicate minerals. In their crystal structure, aluminium can substitute for silicon in tetrahedral sites.



Step 1: Compare feldspar compositions.

Albite has the composition:
\[ NaAlSi_3O_8 \]

Anorthite has the composition:
\[ CaAl_2Si_2O_8 \]



Step 2: Compare Al content.

In albite, there is one aluminium atom for three silicon atoms.

In anorthite, there are two aluminium atoms for two silicon atoms.
\[ Anorthite has more Al substitution for Si \]



Step 3: Final answer.

Therefore, maximum substitution of Al for Si is found in anorthite.
\[ \therefore Correct Answer is (B) \] Quick Tip: Anorthite \((CaAl_2Si_2O_8)\) has greater Al content than albite \((NaAlSi_3O_8)\).

Concept:

The colour of minerals is often due to trace impurities or defects present in the crystal structure.



Step 1: Identify Amethyst.

Amethyst is a purple variety of quartz.
\[ Amethyst=purple quartz \]



Step 2: Cause of purple colour.

The purple colour of amethyst is mainly due to iron impurity along with irradiation effects.
\[ Purple colour \Rightarrow Iron \]



Step 3: Final answer.

Therefore, the colour of amethyst is due to the presence of iron.
\[ \therefore Correct Answer is (A) \] Quick Tip: Amethyst is purple quartz, and its colour is mainly due to iron impurity.

Concept:

Lustre is an important physical property of minerals. It describes how light is reflected from the surface of a mineral.



Step 1: Understand lustre.

Lustre is the appearance or shine of a mineral surface.



Step 2: Relation with light.

Lustre depends on reflected light from the mineral surface.
\[ Lustre=appearance in reflected light \]



Step 3: Final answer.

Thus, lustre is defined as the appearance of a mineral in reflected light.
\[ \therefore Correct Answer is (C) \] Quick Tip: Lustre describes how a mineral surface looks in reflected light.

Concept:

Silica \((SiO_2)\) occurs in different polymorphic forms such as quartz, tridymite, cristobalite and coesite.



Step 1: Understand pseudo-isometric form.

Pseudo-isometric means the crystal appears to have isometric or cubic symmetry, although its actual symmetry may be different.



Step 2: Identify the silica form.

Cristobalite is a high-temperature polymorph of silica and is commonly described as pseudo-isometric.
\[ Pseudo-isometric silica=Cristobalite \]



Step 3: Final answer.

Therefore, the correct form is cristobalite.
\[ \therefore Correct Answer is (A) \] Quick Tip: Cristobalite is a high-temperature silica polymorph and is commonly described as pseudo-isometric.

Concept:

In geological mapping, the relation between dip of beds and land slope helps in understanding the outcrop pattern and age sequence of beds.



Step 1: Understand inclined beds.

Dipping beds are sedimentary layers that are tilted from their original horizontal position.



Step 2: Relation between dip and slope.

When the dip of beds is greater than the slope of the land surface, the progressively younger beds appear in the direction of dip.
\[ Dip>Slope \]



Step 3: Final answer.

Therefore, progressively younger beds occur along the direction of dip when:
\[ Dip>Slope \]
\[ \therefore Correct Answer is (C) \] Quick Tip: For inclined beds, age sequence in outcrop depends on the relation between dip of beds and topographic slope.

Concept:

Folds are bends or curves in rock layers caused by compressional forces. They are classified based on the geometry of their limbs and axial plane.



Step 1: Understand fold limbs.

The two sides of a fold are called limbs.



Step 2: Identify fold with parallel limbs.

In an isoclinal fold, the two limbs are nearly parallel to each other.
\[ Parallel limbs \Rightarrow Isoclinal fold \]



Step 3: Final answer.

Thus, a fold with parallel limbs is an isoclinal fold.
\[ \therefore Correct Answer is (B) \] Quick Tip: Isoclinal folds have limbs that are nearly parallel to each other.

Concept:

Outcrop patterns of folds depend on whether the fold is plunging, non-plunging or doubly plunging.



Step 1: Understand elliptical outcrop pattern.

An elliptical outcrop pattern is produced when the fold closes at both ends.



Step 2: Identify the fold type.

A doubly plunging fold plunges in two opposite directions. Because of this, the outcrop pattern becomes elliptical or closed on a level surface.
\[ Elliptical outcrop \Rightarrow Doubly plunging fold \]



Step 3: Final answer.

Therefore, elliptical outcrops are commonly exhibited by doubly plunging folds.
\[ \therefore Correct Answer is (B) \] Quick Tip: Doubly plunging folds commonly produce elliptical or closed outcrop patterns.

Concept:

Wind erosion produces several landforms in arid and semi-arid regions. Abrasion is the sand-blasting action of wind.



Step 1: Understand the described shape.

The question describes a mushroom-shaped structure with a narrow base and wider top.



Step 2: Cause of formation.

Wind abrasion is stronger near the ground because sand particles move close to the surface. Therefore, lower parts of rocks are eroded more than upper parts.



Step 3: Identify the landform.

Such mushroom-shaped rocks are known as pedestal rocks.
\[ Mushroom-shaped wind-eroded rock=Pedestal rock \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Pedestal rocks are formed by differential wind abrasion near the ground surface.

Concept:

Deltas are depositional environments formed where rivers enter standing bodies of water such as lakes or seas.



Step 1: Understand delta deposition.

In deltaic environments, sediments are deposited by flowing water, distributary channels and current action.



Step 2: Identify common sedimentary structure.

Cross bedding is commonly formed by migration of ripples, dunes or bars under current action.
\[ Deltaic current deposition \Rightarrow Cross bedding \]



Step 3: Final answer.

Thus, the sedimentary structure mostly found in delta among the given options is cross bedding.
\[ \therefore Correct Answer is (D) \] Quick Tip: Cross bedding commonly forms in current-dominated depositional environments such as rivers and deltas.

Concept:

Cirques are bowl-shaped depressions found at the head of glacial valleys. They are associated with glacial and snow-related erosional processes.



Step 1: Understand cirque formation.

Cirques form in areas where snow accumulates and gradually modifies the underlying rock surface.



Step 2: Identify the process.

Nivation is the process of erosion and weathering associated with snow patches. It plays an important role in the origin of cirques.
\[ Cirque origin \Rightarrow Nivation \]



Step 3: Eliminate other options.

Abrasion is scraping action by ice or sediments.

Ablation means melting or loss of ice.

Calvation is not the correct process here.
\[ \therefore Correct Answer is (D) \] Quick Tip: Cirques are commonly associated with nivation and glacial erosion at the heads of valleys.

Concept:

Groundwater is classified according to its position below the ground surface and its origin.



Step 1: Understand zone of aeration.

The zone of aeration lies above the water table. In this zone, pores contain both air and water.



Step 2: Identify water in zone of aeration.

Water present in the zone of aeration is called vadose water.
\[ Zone of aeration water=Vadose water \]



Step 3: Eliminate other options.

Connate water is trapped in sediments during deposition.

Meteoric water is derived from precipitation.

Plutonic water is associated with deep-seated magmatic sources.
\[ \therefore Correct Answer is (A) \] Quick Tip: Vadose water occurs above the water table in the zone of aeration.

Concept:

Diagnostic mineral properties help in the identification of minerals. Some properties are more reliable than others.



Step 1: Reliable diagnostic properties.

Hardness, lustre and streak are commonly used for mineral identification.
\[ Hardness, Lustre, Streak \Rightarrow useful diagnostic properties \]



Step 2: Why colour is less reliable.

Colour may vary due to impurities, weathering or defects in the mineral.

For example, quartz may occur in many colours.



Step 3: Final answer.

Because colour is not always reliable for diagnosis, it is not considered a strong diagnostic property in this context.
\[ \therefore Correct Answer is (D) \] Quick Tip: Streak is usually more reliable than colour for mineral identification.

Concept:

Polymorphism means the same chemical composition occurring in more than one crystal structure. In sheet silicates, different stacking arrangements may produce many structural variants.



Step 1: Understand mica group.

Mica minerals are sheet silicates. Their layered structure allows different stacking arrangements.



Step 2: Polymorphs/polytypes in mica.

Because mica layers can stack in several ways, mica commonly shows many polymorphic or polytypic forms.
\[ Mica \Rightarrow large number of polymorphs/polytypes \]



Step 3: Final answer.

Among the given mineral groups, mica shows the highest number of polymorphs.
\[ \therefore Correct Answer is (D) \] Quick Tip: Mica minerals commonly show many structural variants because of different layer stacking arrangements.

Concept:

Ionic radius depends on ionic charge and electronic configuration. Generally, higher positive charge pulls electrons more strongly and produces a smaller ionic radius.



Step 1: Compare charges.

The ions given are:
\[ Na^+,\ Mg^{2+},\ Al^{3+},\ Si^{4+} \]



Step 2: Effect of increasing charge.

As positive charge increases, the nucleus attracts the electron cloud more strongly.
\[ Na^+>Mg^{2+}>Al^{3+}>Si^{4+} \]

in terms of ionic radius.



Step 3: Identify least radius.

Thus, \(Si^{4+}\) has the least ionic radius among the given ions.
\[ \therefore Correct Answer is (C) \] Quick Tip: For related cations, higher positive charge generally means smaller ionic radius.

Concept:

Unconformity represents a break in the geological record due to erosion or non-deposition.



Step 1: Types of unconformity.

Important types of unconformity include:
\[ Nonconformity \] \[ Paraconformity \] \[ Disconformity \]



Step 2: Understand klippe.

A klippe is an isolated remnant of a thrust sheet separated from the main mass by erosion.

It is a structural geology term and is not a type of unconformity.



Step 3: Final answer.

Therefore, the term not related to unconformity is:
\[ Klippe \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Nonconformity, paraconformity and disconformity are unconformity types; klippe is related to thrust tectonics.

Concept:

In geological maps, the relation between outcrop patterns and contour lines helps determine the attitude of beds.



Step 1: Understand contour lines.

Contour lines join points of equal elevation.



Step 2: Interpret parallelism.

If the outcrop of a bedding plane runs parallel to contour lines, it means the bed is at the same elevation along its trace.

This condition indicates that the bed is horizontal.
\[ Bedding trace parallel to contours \Rightarrow Horizontal bed \]



Step 3: Final answer.

Therefore, parallelism of contour lines and bedding plane indicates:
\[ Horizontal bed \]
\[ \therefore Correct Answer is (A) \] Quick Tip: In a geological map, a horizontal bed generally follows contour lines.

Concept:

Trilobites had biramous appendages, meaning each appendage was divided into two branches.



Step 1: Understand biramous appendage.

A biramous appendage has two main branches: \[ Outer branch \]
and \[ Inner branch \]



Step 2: Function of the walking branch.

The walking branch of the trilobite appendage is called the telopodite.
\[ Walking branch=Telopodite \]



Step 3: Eliminate other options.

Coxa is a basal part.

Outer ramus is generally related to the outer branch.

Semipodite is not the correct term for the walking branch in this question.
\[ \therefore Correct Answer is (D) \] Quick Tip: In trilobite biramous appendages, the walking branch is known as telopodite.

Concept:

Pelecypods, also called bivalves, may live as burrowing organisms. Their shell features help identify their mode of life.



Step 1: Understand pallial sinus.

Pallial sinus is an inward bend in the pallial line of a bivalve shell.



Step 2: Relation with burrowing habit.

Burrowing bivalves have long siphons. These siphons need space for retraction inside the shell.
\[ Long siphons \Rightarrow Pallial sinus \]



Step 3: Final conclusion.

Therefore, pallial sinus indicates burrowing habit in pelecypods.
\[ \therefore Correct Answer is (A) \] Quick Tip: Pallial sinus in bivalves usually indicates siphon-bearing and burrowing habit.

Concept:

In stratigraphy, older rock groups occur lower in the geological time sequence, while younger groups are deposited later.



Step 1: Identify the groups.

The given groups belong to Precambrian stratigraphy of the Indian shield region.



Step 2: Compare relative ages.

Sargur Group is among the oldest supracrustal rock sequences.
\[ Sargur Group \Rightarrow older than Bababudan and Chitradurga groups \]



Step 3: Final answer.

Thus, the oldest stratigraphically among the given options is Sargur Group.
\[ \therefore Correct Answer is (B) \] Quick Tip: In Indian Precambrian stratigraphy, the Sargur Group is considered older than the Dharwar Supergroup units.

Concept:

Sedimentary rocks are classified using several features such as texture, composition, origin and depositional environment.



Step 1: Understand texture.

Texture includes grain size, sorting, roundness and arrangement of particles.



Step 2: Importance of texture.

Texture is very important because it directly tells about the nature of sediment, transport history and depositional conditions.
\[ Texture \Rightarrow grain size, sorting and arrangement \]



Step 3: Final answer.

Among the given options, texture is the most important basis for classification.
\[ \therefore Correct Answer is (D) \] Quick Tip: Texture is a key basis of sedimentary rock classification because it reflects grain size and depositional character.

Concept:

Karst topography develops mainly in soluble rocks such as limestone and dolomite.



Step 1: Required rock type.

Karst landforms require soluble rocks because groundwater dissolves the rock.
\[ Limestone+carbonic acid water\Rightarrow solution activity \]



Step 2: Role of joints.

Extensive joints allow water to enter deeply into the rock.
\[ Joints \Rightarrow easy movement of water \]



Step 3: Final answer.

Therefore, soluble rocks with extensive jointing provide the most suitable condition for karst topography.
\[ \therefore Correct Answer is (C) \] Quick Tip: Karst topography develops best in soluble, jointed limestone regions.

Concept:

Sedimentary structures form under specific depositional conditions. Cross bedding and graded bedding represent different energy and flow conditions.



Step 1: Cross bedding.

Cross bedding forms due to migration of ripples, dunes or bars under current action.
\[ Cross bedding \Rightarrow traction current conditions \]



Step 2: Graded bedding.

Graded bedding forms when particles settle from suspension, usually from a waning current.
\[ Graded bedding \Rightarrow settling from suspension \]



Step 3: Compare both.

Since both structures represent different depositional environments and processes, they normally do not occur together.
\[ \therefore Correct Answer is (C) \] Quick Tip: Cross bedding indicates current action, while graded bedding indicates settling from suspension.

Concept:

Index fossils are used for correlation and relative dating of sedimentary rocks.



Step 1: Geographic distribution.

A good index fossil should be widely distributed geographically so that it can be found in many regions.
\[ Index fossil \Rightarrow wide geographic distribution \]



Step 2: Time range.

A good index fossil should exist for a short geological time interval.
\[ Index fossil \Rightarrow limited stratigraphic range \]



Step 3: Final answer.

Therefore, index fossils have wide geographic distribution and limited stratigraphic range.
\[ \therefore Correct Answer is (D) \] Quick Tip: A good index fossil is widespread geographically but short-lived stratigraphically.

Concept:

Brachiopods are marine invertebrates having two shells or valves, but their shell symmetry differs from pelecypods.



Step 1: Valve size.

In brachiopods, the two valves are generally unequal in size.
\[ Pedicle valve\neq brachial valve \]



Step 2: Symmetry.

Each valve is bilaterally symmetrical about a median plane, giving equilateral symmetry.



Step 3: Final answer.

Thus, brachiopod valves are unequal in size with equilateral symmetry.
\[ \therefore Correct Answer is (C) \] Quick Tip: Brachiopods have unequal valves, but each valve is bilaterally symmetrical.

Concept:

Foliation is the planar arrangement of minerals in metamorphic rocks.



Step 1: Role of stress.

Directed stress causes platy and elongated minerals to align perpendicular to maximum compression.
\[ Directed stress \Rightarrow preferred mineral orientation \]



Step 2: Role of temperature.

Temperature helps minerals recrystallize during metamorphism.
\[ Temperature \Rightarrow recrystallization \]



Step 3: Final answer.

Thus, stress and temperature are the most important factors for foliation development.
\[ \therefore Correct Answer is (D) \] Quick Tip: Foliation develops mainly due to directed stress and recrystallization during metamorphism.

Concept:

Rhombohedron is a form related to the trigonal division of the hexagonal crystal system.



Step 1: Identify the symmetry.

A rhombohedron has symmetry planes that are diagonal in nature.



Step 2: Eliminate other options.

It is not mainly characterized by horizontal symmetry planes. The important symmetry planes associated here are diagonal symmetry planes.
\[ Rhombohedron \Rightarrow Diagonal symmetry planes \]
\[ \therefore Correct Answer is (B) \] Quick Tip: Rhombohedron is commonly associated with diagonal symmetry planes.

Concept:

Island arcs are associated with subduction zones and active volcanism. Fissure volcanism is a different style of volcanic eruption.



Step 1: Check Assertion.

Island arc systems are volcanically active and may produce earthquakes, eruptions, tsunamis and other disasters.
\[ A is correct \]



Step 2: Check Reason.

Fissure eruptions allow lava to spread over wide areas.
\[ R is correct \]



Step 3: Check explanation.

Reason talks about fissure volcanism, but Assertion talks about volcanic disasters in island arcs. It does not directly explain the Assertion.
\[ \therefore Correct Answer is (B) \] Quick Tip: Both statements may be true, but in assertion-reason questions, the reason must directly explain the assertion.

Concept:

Gypsum is hydrated calcium sulphate, while anhydrite is anhydrous calcium sulphate.



Step 1: Compare minerals.

Gypsum: \[ CaSO_4\cdot 2H_2O \]

Anhydrite: \[ CaSO_4 \]



Step 2: Effect of hydration.

Hydration increases volume because water molecules enter the crystal structure.
\[ Volume increases \Rightarrow density decreases \]



Step 3: Final conclusion.

Gypsum has lower density than anhydrite, and the reason correctly explains it.
\[ \therefore Correct Answer is (A) \] Quick Tip: Gypsum is hydrated calcium sulphate, while anhydrite is anhydrous calcium sulphate.

Concept:

Drumlins and roches moutonnees are glacial landforms, but their shapes and mode of formation differ.



Step 1: Check Assertion.

Drumlins are streamlined depositional landforms, while roches moutonnees are erosional landforms. Their profiles are opposite in important respects.
\[ A is correct \]



Step 2: Check Reason.

The given reason says the stoss side is steep and lee side is roughened. This is not the correct description for drumlins in this context.
\[ R is not correct \]



Step 3: Final conclusion.

Assertion is correct, but Reason is incorrect.
\[ \therefore Correct Answer is (C) \] Quick Tip: Roches moutonnees are erosional glacial landforms, while drumlins are streamlined depositional landforms.

Concept:

Quartz and orthoclase can be distinguished in hand specimen using physical properties.



Step 1: Check Assertion.

Quartz commonly shows conchoidal fracture and lacks cleavage, while orthoclase has two good cleavages.
\[ A is correct \]



Step 2: Check Reason.

Orthoclase has slightly lower refractive index than quartz.
\[ R is correct \]



Step 3: Check explanation.

Refractive index is not the main hand-specimen basis for distinguishing quartz from orthoclase. Cleavage and fracture are more useful in hand specimen.
\[ R is not the correct explanation of A \]
\[ \therefore Correct Answer is (B) \] Quick Tip: Quartz lacks cleavage and shows conchoidal fracture, while orthoclase shows cleavage.

Concept:

Earthquake waves are mainly body waves and surface waves. Surface waves generally cause the greatest destruction.



Step 1: Check Assertion.

L waves are surface waves and are responsible for much of the earthquake destruction.
\[ A is correct \]



Step 2: Check Reason.

L waves develop near the surface and travel along the Earth's surface.
\[ R is correct \]



Step 3: Check explanation.

Because L waves are surface waves, their amplitude near the surface is large and they cause strong damage.
\[ R correctly explains A \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Surface waves or L waves are generally the most destructive earthquake waves.

Concept:

Continental drift theory states that continents were once joined together and later drifted apart.



Step 1: Check Assertion.

The concept of supercontinents suggests that continents were joined together in the geological past.
\[ A is correct \]



Step 2: Check Reason.

Glossopteris and Gangamopteris flora are found on southern continents such as India, Africa, Australia, Antarctica and South America.
\[ R is correct \]



Step 3: Check explanation.

The occurrence of similar fossil flora on separated continents supports the idea that they were once connected.
\[ R correctly explains A \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Glossopteris fossil flora is important evidence for continental drift and Gondwana connection.

Concept:

Faults are classified according to the direction of slip relative to the fault plane.



Step 1: Check Assertion.

A dip-slip fault involves movement mainly along the dip direction. A wrench fault is mainly a strike-slip fault.
\[ A is not correct \]



Step 2: Check Reason.

Net slip on a fault may be strike-slip, dip-slip or oblique-slip depending on the movement direction.
\[ R is correct \]



Step 3: Final conclusion.

Assertion is incorrect, but Reason is correct.
\[ \therefore Correct Answer is (D) \] Quick Tip: Dip-slip faults move along dip direction, while wrench faults are strike-slip faults.

Concept:

Chronostratigraphy deals with the age and time relationship of rock strata.



Step 1: Check Assertion.

Chronostratigraphy is concerned with the mutual time relationship of strata.
\[ A is correct \]



Step 2: Check Reason.

Formation, member and bed are lithostratigraphic units, not chronostratigraphic units.
\[ R is not correct \]



Step 3: Final conclusion.

Assertion is correct, but Reason is incorrect.
\[ \therefore Correct Answer is (C) \] Quick Tip: Formation, member and bed are lithostratigraphic units; chronostratigraphy deals with time-rock units.

Concept:

Interfacial angle is an important crystallographic property used in crystal identification.



Step 1: Check Assertion.

The angle between two crystal faces is called the interfacial angle.
\[ A is correct \]



Step 2: Check Reason.

According to the law of constancy of interfacial angles, corresponding faces of crystals of the same substance show constant angles under the same conditions.
\[ R is correct \]



Step 3: Check explanation.

Reason states an important law about interfacial angles, but it does not define why the angle between two faces is called interfacial angle.
\[ R is not the correct explanation of A \]
\[ \therefore Correct Answer is (B) \] Quick Tip: Interfacial angles remain constant for corresponding faces of crystals of the same substance.

Concept:

Volcanic eruptions are classified according to explosiveness, magma viscosity and gas content.



Step 1: Least explosive type.

Hawaiian eruptions are usually quiet and effusive.
\[ Least explosive=A \]



Step 2: Next stages.

Strombolian eruptions are more explosive than Hawaiian eruptions.
\[ A
Vulcanian eruptions are more explosive than Strombolian eruptions.
\[ C


Step 3: Highly explosive types.

Vesuvian eruptions are highly explosive, and Plinian eruptions are among the most explosive.
\[ B


Step 4: Final sequence. \[ A,C,B,D,E \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Increasing explosiveness: Hawaiian \(\rightarrow\) Strombolian \(\rightarrow\) Vulcanian \(\rightarrow\) Vesuvian \(\rightarrow\) Plinian.

Concept:

Weathering stability of minerals depends on their resistance to chemical and physical weathering. Minerals formed at lower temperature are generally more stable at the Earth's surface, while high-temperature minerals weather faster.



Step 1: Identify the most stable mineral.

Quartz is highly resistant to weathering because it has a strong silicon-oxygen framework structure.
\[ Quartz=most stable \]

So,
\[ B comes first \]



Step 2: Compare muscovite and hornblende.

Muscovite is a mica mineral and is more stable than hornblende during weathering.
\[ Muscovite>Hornblende \]

So,
\[ A comes before D \]



Step 3: Identify the least stable mineral.

Olivine is a high-temperature ferromagnesian mineral and weathers very easily at the Earth's surface.
\[ Olivine=least stable \]

So,
\[ C comes last \]



Step 4: Final sequence.

The decreasing order of weathering stability is:
\[ Quartz>Muscovite>Hornblende>Olivine \]

Using the given letters:
\[ B>A>D>C \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Quartz is highly stable during weathering, while olivine is one of the least stable common silicate minerals.

Concept:

The Vindhyan Supergroup is divided into several groups arranged from older to younger. Correct stratigraphic order is important for understanding geological history.



Step 1: Identify the oldest group.

The Semri Group is the oldest among the given Vindhyan groups.
\[ Oldest=B \]



Step 2: Identify the next group.

After Semri Group comes the Kaimur Group.
\[ Second=D \]



Step 3: Identify the next younger group.

After Kaimur Group comes the Rewa Group.
\[ Third=A \]



Step 4: Identify the youngest group.

The Bhander Group is the youngest among these.
\[ Youngest=C \]



Therefore, the sequence from older to younger is:
\[ Semri \rightarrow Kaimur \rightarrow Rewa \rightarrow Bhander \]

Using the given letters:
\[ B>D>A>C \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Vindhyan sequence from older to younger is Semri \(\rightarrow\) Kaimur \(\rightarrow\) Rewa \(\rightarrow\) Bhander.

Concept:

The abundance of elements in the universe is dominated by light elements. Hydrogen is the most abundant element, followed by helium.



Step 1: Identify the most abundant element.

Hydrogen is the most abundant element in the universe.
\[ Hydrogen=A \]

So,
\[ A comes first \]



Step 2: Identify the second most abundant element.

Helium is the second most abundant element.
\[ Helium=B \]

So,
\[ B comes after A \]



Step 3: Compare oxygen, neon and nitrogen.

Among oxygen, neon and nitrogen, oxygen is more abundant than neon and nitrogen. Neon is generally more abundant than nitrogen in cosmic abundance.
\[ O>Ne>N \]

Using the given letters:
\[ D>E>C \]



Step 4: Final decreasing order.

Therefore, the decreasing order is:
\[ H>He>O>Ne>N \]
\[ A>B>D>E>C \]
\[ \therefore Correct Answer is (B) \] Quick Tip: Universal abundance generally starts with Hydrogen, then Helium, followed by heavier elements such as Oxygen and Neon.

Concept:

Chronostratigraphic units are rock units arranged according to geological time. They have a hierarchical order from larger to smaller.



Step 1: Identify the largest unit among the given options.

System is larger than series, stage and zone.
\[ Largest=D \]



Step 2: Identify the next unit.

A system is divided into series.
\[ Second=B \]



Step 3: Identify the next smaller unit.

A series is divided into stages.
\[ Third=A \]



Step 4: Identify the smallest unit.

Zone is smaller than stage in this sequence.
\[ Smallest=C \]



Therefore, the correct order from larger to smaller is:
\[ System>Series>Stage>Zone \]

Using letters:
\[ D>B>A>C \]
\[ \therefore Correct Answer is (B) \] Quick Tip: Chronostratigraphic order is System \(\rightarrow\) Series \(\rightarrow\) Stage \(\rightarrow\) Zone.

Concept:

In geology, decreasing order of age means arranging from oldest to youngest.



Step 1: Identify the oldest volcanic unit.

Among the given volcanic units, Pitepani volcanics are older than the others.
\[ Oldest=C \]



Step 2: Identify the next older unit.

Malani volcanics are Proterozoic and are older than Panjal and Dras volcanics.
\[ Second=D \]



Step 3: Compare Panjal and Dras.

Panjal volcanics are older than Dras volcanics.
\[ A>B \]



Step 4: Final decreasing order.

Therefore, from older to younger:
\[ Pitepani>Malani>Panjal>Dras \]

Using letters:
\[ C>D>A>B \]
\[ \therefore Correct Answer is (B) \] Quick Tip: For age-order questions, decreasing order means oldest to youngest.

Concept:

Specific gravity is the density of a mineral relative to water. Heavy minerals have higher specific gravity.



Step 1: Identify the lowest specific gravity.

Quartz has relatively low specific gravity, about \(2.65\).
\[ Quartz=C \]

So,
\[ C comes first \]



Step 2: Compare anthophyllite and hypersthene.

Anthophyllite has higher specific gravity than quartz but generally lower than hypersthene.
\[ D


Step 3: Identify the highest specific gravity.

Magnetite is an iron oxide mineral and has high specific gravity.
\[ Magnetite=A \]

So,
\[ A comes last in increasing order \]



Step 4: Final increasing order.

The increasing order is:
\[ Quartz
Using letters:
\[ C \[ \therefore Correct Answer is (C) \] Quick Tip: Magnetite has high specific gravity because it is rich in iron.

Concept:

Stratigraphic position is arranged from older beds at the bottom to younger beds above.



Step 1: Identify the oldest zone.

Otoceras zone is the oldest among the given stratigraphic units.
\[ Oldest=A \]



Step 2: Identify the next bed.

Hedenstroemia bed comes after Otoceras zone.
\[ Second=E \]



Step 3: Identify middle units.

Daonella Limestone is followed by Monotis shale.
\[ C>D \]



Step 4: Identify the youngest unit.

Megalodon limestone is the youngest among the given units.
\[ Youngest=B \]



Therefore, the older to younger sequence is:
\[ A>E>C>D>B \]
\[ \therefore Correct Answer is (B) \] Quick Tip: In stratigraphy, older to younger order means moving upward in the geological sequence.

Concept:

The Earth's crust is dominated by silicate minerals, so silica is the most abundant oxide.



Step 1: Identify the most abundant oxide.

Silica \((SiO_2)\) is the most abundant oxide in the Earth's crust.
\[ D comes first \]



Step 2: Identify the second most abundant oxide.

Alumina \((Al_2O_3)\) is next after silica.
\[ A comes second \]



Step 3: Compare iron oxides and calcium oxide.

Total iron oxides are generally more abundant than calcium oxide.
\[ B>C \]



Step 4: Final decreasing order.

Therefore, the decreasing order is:
\[ SiO_2>Al_2O_3>(Fe_2O_3+FeO)>CaO \]

Using letters:
\[ D>A>B>C \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Silica \((SiO_2)\) is the most abundant oxide in the Earth's crust.

Concept:

Metamorphic grade increases with increasing temperature and pressure. Shale transforms into progressively higher grade metamorphic rocks.



Step 1: Start with parent rock.

Shale is the original sedimentary rock.
\[ Lowest=A \]



Step 2: Low-grade metamorphism.

Shale first changes into slate.
\[ Slate=E \]



Step 3: Next grade.

Slate changes into phyllite.
\[ Phyllite=D \]



Step 4: Higher grade.

Phyllite changes into schist.
\[ Schist=B \]



Step 5: Highest grade among these.

Schist changes into gneiss at still higher metamorphic grade.
\[ Highest=C \]



Therefore, increasing grade of metamorphism is:
\[ Shale
Using letters:
\[ A \[ \therefore Correct Answer is (C) \] Quick Tip: Metamorphic sequence of shale is Shale \(\rightarrow\) Slate \(\rightarrow\) Phyllite \(\rightarrow\) Schist \(\rightarrow\) Gneiss.

Concept:

Barrovian metamorphic zones show progressive regional metamorphism. They are arranged from low grade to high grade according to index minerals.



Step 1: Lowest grade zone.

Chlorite zone represents the lowest grade Barrovian metamorphic zone.
\[ Lowest=E \]



Step 2: Next zone.

After chlorite zone comes biotite zone.
\[ Second=A \]



Step 3: Intermediate zones.

After biotite zone comes garnet zone, then staurolite zone.
\[ D>B \]



Step 4: Higher grade zone.

Kyanite zone represents higher grade metamorphism among the given zones.
\[ Highest=C \]



Therefore, the progressive sequence is:
\[ Chlorite\rightarrow Biotite\rightarrow Garnet\rightarrow Staurolite\rightarrow Kyanite \]

Using letters:
\[ E>A>D>B>C \]
\[ \therefore Correct Answer is (B) \] Quick Tip: Barrovian zones progress as Chlorite \(\rightarrow\) Biotite \(\rightarrow\) Garnet \(\rightarrow\) Staurolite \(\rightarrow\) Kyanite.

Concept:

Silica \((SiO_2)\) has different polymorphs stable at different temperatures.



Step 1: Highest temperature form.

Cristobalite is stable at very high temperature among the given silica forms.
\[ Highest=B \]



Step 2: Next temperature form.

Tridymite is stable below cristobalite but above quartz forms.
\[ Second=A \]



Step 3: Quartz forms.

High quartz exists at higher temperature than low quartz.
\[ D>C \]



Step 4: Final decreasing temperature order.

Thus, the sequence is:
\[ Cristobalite>Tridymite>High quartz>Low quartz \]

Using letters:
\[ B>A>D>C \]
\[ \therefore Correct Answer is (C) \] Quick Tip: Silica polymorphs in decreasing temperature are Cristobalite \(\rightarrow\) Tridymite \(\rightarrow\) High quartz \(\rightarrow\) Low quartz.

Concept:

Faults are fractures in rocks along which displacement has taken place. They are produced by different types of tectonic forces.



Step 1: Shear forces.

Shear forces produce strike-slip or wrench faults.
\[ A is correct \]



Step 2: Extensional forces.

Extensional forces pull rocks apart and commonly produce normal faults.
\[ B is correct \]



Step 3: Compressional forces.

Compressional forces push rocks together and commonly produce reverse or thrust faults.
\[ C is correct \]



Step 4: Torsional forces.

Torsional forces can also contribute to fracturing and displacement of rocks.
\[ D is correct \]



Thus, all given forces can generate faults.
\[ \therefore Correct Answer is (D) \] Quick Tip: Normal faults are related to extension, reverse faults to compression, and strike-slip faults to shear.

Concept:

Porosity is the percentage of void space present in a rock.
\[ Porosity=\frac{Volume of voids}{Total volume}\times100 \]



Step 1: Shape of grains.

The shape of grains affects how much pore space remains between grains.
\[ A is correct \]



Step 2: Packing of grains.

Loose packing gives higher porosity, while tight packing gives lower porosity.
\[ B is correct \]



Step 3: Size of grains.

Grain size may influence the arrangement of grains and pore spaces.
\[ C is correct \]



Step 4: Interconnectivity of void spaces.

Interconnectivity of void spaces is more directly related to permeability, not porosity.
\[ D is not selected \]



Thus, porosity depends mainly on:
\[ A,B,C \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Porosity is about the amount of pore space, while permeability is about interconnection of pore spaces.

Concept:

Bowen's Reaction Series explains the order in which minerals crystallize from cooling magma.



Step 1: Check statement A.

Bowen's Reaction Series is not related to destruction of rocks under stress.
\[ A is incorrect \]



Step 2: Check statement B.

It is not related to animal behaviour or climate response.
\[ B is incorrect \]



Step 3: Check statement C.

Bowen's Reaction Series explains crystallisation of minerals from cooling magma.
\[ C is correct \]



Step 4: Check statement D.

Bowen's Reaction Series has two branches:
\[ Continuous series \]

and
\[ Discontinuous series \]

So,
\[ D is correct \]



Thus, the correct statements are:
\[ C,D \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Bowen's Reaction Series explains mineral crystallisation from cooling magma and includes continuous and discontinuous branches.

Concept:

Magmatic origin of granite means granite formed from crystallisation of magma. Certain field and textural features support this origin.



Step 1: Chilled margins.

Chilled margins form when magma cools rapidly against cooler country rocks.
\[ A is evidence of magmatic origin \]



Step 2: Perfect gradation with country rocks.

Perfect gradation between country rocks and granite is more commonly used as an argument for replacement or metasomatic origin, not direct magmatic origin.
\[ B is not selected \]



Step 3: Xenoliths.

Xenoliths are fragments of country rocks enclosed in magma. Their presence in granite supports intrusion of magma.
\[ C is correct \]



Step 4: Graphic texture.

Graphic texture may develop during crystallisation of granitic magma and supports magmatic origin.
\[ D is correct \]



Thus, the correct evidence set is:
\[ A,C,D \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Chilled margins, xenoliths and magmatic textures support igneous or magmatic origin of granite.

Concept:

Hemihedral forms are crystal forms having half the number of faces compared to the corresponding holohedral form.



Step 1: Check statement A.

Hemihedral forms do not represent the same full symmetry condition as holohedral forms.
\[ A is not selected \]



Step 2: Check statement B.

Hemihedral forms can have the same indices as the corresponding holohedral form.
\[ B is correct \]



Step 3: Check statement C.

By definition, hemihedral forms have half the number of faces of the holohedral form.
\[ C is correct \]



Step 4: Check statement D.

For a holohedral form, two corresponding hemihedral forms may occur.
\[ D is correct \]



Therefore, the correct statements are:
\[ B,C,D \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Hemihedral forms have half the number of faces of the corresponding holohedral form.

Concept:

Residual concentration forms ore deposits by intense weathering and leaching. Soluble materials are removed, while less soluble valuable materials remain concentrated.



Step 1: Iron.

Iron ores may form by residual concentration through lateritic weathering.
\[ A is correct \]



Step 2: Nickel.

Nickel laterite deposits are formed by residual concentration of nickel during weathering of ultramafic rocks.
\[ B is correct \]



Step 3: Copper.

Copper is not the typical residual concentration mineral in the given set.
\[ C is not selected \]



Step 4: Aluminium.

Bauxite, the chief ore of aluminium, is formed by residual concentration.
\[ D is correct \]



Thus, the correct set is:
\[ A,B,D \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Bauxite and nickel laterite are important examples of residual concentration deposits.

Concept:

Ionic bonding forms due to electrostatic attraction between oppositely charged ions.



Step 1: Check statement A.

Halite \((NaCl)\) is a classic example of ionic bonding.
\[ Na^+ + Cl^- \rightarrow NaCl \]

So,
\[ A is correct \]



Step 2: Check statement B.

Diamond is very hard because of strong covalent bonding, not ionic bonding.
\[ B is incorrect \]



Step 3: Check statement C.

Ionic solids form crystal lattices rather than discrete molecules, but in the given option set the suitable complete correct pair is not based on C alone.



Step 4: Check statement D.

Ionic minerals usually have high melting points and are mechanically hard and strong due to strong electrostatic forces.
\[ D is correct \]



Thus, the correct option is:
\[ A,D \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Halite is ionic, while diamond is covalent.

Concept:

Optically isotropic minerals have the same optical properties in all directions.



Step 1: Check statement A.

Optically isotropic minerals are not necessarily opaque. Many isotropic minerals transmit light.
\[ A is incorrect \]



Step 2: Check statement B.

In isotropic minerals, light travels with the same velocity in all directions.
\[ B is correct \]



Step 3: Check statement C.

If refractive index varies with direction, the mineral is anisotropic, not isotropic.
\[ C is incorrect \]



Step 4: Check statement D.

Garnet belongs to the cubic system and is optically isotropic.
\[ D is correct \]



Thus, the correct statements are:
\[ B,D \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Isotropic minerals have the same refractive index in all directions; garnet is an example.

Concept:

Coal forms from accumulation and preservation of plant material in swampy environments. Climate and water conditions play an important role.



Step 1: Warm and humid climate.

Warm and humid climate supports dense vegetation growth, which provides large amounts of plant material.
\[ A is correct \]



Step 2: Marine environment.

Coal generally forms in swampy, marshy, deltaic or continental wetland environments rather than typical open marine environments.
\[ B is not selected \]



Step 3: Cold climate.

Cold climate is not the most favourable condition for abundant vegetation and coal formation.
\[ C is incorrect \]



Step 4: Heavy rainfall.

Heavy rainfall supports swampy conditions and abundant plant growth, both favourable for coal formation.
\[ D is correct \]



Thus, favourable conditions are:
\[ A,D \]
\[ \therefore Correct Answer is (C) \] Quick Tip: Coal formation is favoured by warm, humid, swampy conditions with abundant vegetation.

Concept:

Migmatite is a mixed rock showing both metamorphic and igneous characters. It is commonly formed under very high-grade metamorphic conditions where partial melting takes place.



Step 1: Check statement A.

Migmatite contains both metamorphic portions and igneous-looking melted portions.
\[ A is correct \]



Step 2: Check statement B.

Migmatites generally form under high temperature and high pressure conditions during high-grade metamorphism.
\[ B is correct \]



Step 3: Check statement C.

During partial melting, felsic material may separate from darker mafic material.
\[ C is correct \]



Step 4: Check statement D.

Prolonged activity of chemically active fluids is more closely related to metasomatism, not the main formation process of migmatite.
\[ D is incorrect \]



Thus, the correct statements are:
\[ A,B,C \]
\[ \therefore Correct Answer is (C) \] Quick Tip: Migmatite is formed by partial melting during high-grade metamorphism and shows both igneous and metamorphic features.

Concept:

The Dharwar succession of Karnataka belongs to the Precambrian rocks. Its division is mainly based on geological relationships and age data.



Step 1: Check unconformity.

Unconformity is an important geological break between rock successions and helps divide older and younger units.
\[ A is correct \]



Step 2: Check fossil evidence.

Dharwar rocks are Precambrian, so fossil evidence is not the main basis for division.
\[ B is incorrect \]



Step 3: Check geochronological data.

Geochronological data gives numerical age information and helps distinguish Lower and Upper Dharwar successions.
\[ C is correct \]



Step 4: Check economic minerals.

Economic minerals may occur in these rocks, but they are not the main formal basis for dividing the succession.
\[ D is incorrect \]



Therefore, the correct statements are:
\[ A,C \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Lower and Upper Dharwar divisions are mainly based on unconformity and geochronological data.

Concept:

Schistosity is a planar fabric in metamorphic rocks formed by parallel alignment of platy or flaky minerals.



Step 1: Understand schistosity.

Schistosity develops when minerals such as mica align under directed pressure and recrystallization.
\[ Directed pressure+recrystallization\Rightarrow schistosity \]



Step 2: Check dynamothermal metamorphism.

Dynamothermal metamorphism involves both heat and directed pressure. This is the most suitable condition for schistosity formation.
\[ A is correct \]



Step 3: Check contact and thermal metamorphism.

Contact and thermal metamorphism are mainly caused by heat. They generally produce non-foliated textures rather than strong schistosity.
\[ B and D are incorrect \]



Step 4: Check plutonic metamorphism.

Plutonic metamorphism is mainly associated with deep-seated pressure-temperature conditions, but schistosity is specifically related to directed stress in dynamothermal metamorphism.
\[ C is not selected \]



Thus, the correct answer is:
\[ A only \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Schistosity forms mainly due to directed pressure during dynamothermal metamorphism.

Concept:

Crystal forms are associated with particular crystal systems based on their symmetry.



Step 1: Match Sphenoid.

Sphenoid is associated with the tetragonal system in the given classification.
\[ A\rightarrow III \]



Step 2: Match Rhombohedron.

Rhombohedron is a characteristic form of the trigonal system.
\[ B\rightarrow I \]



Step 3: Match Scalenohedron.

In the given matching set, scalenohedron corresponds to the orthorhombic system.
\[ C\rightarrow IV \]



Step 4: Match Dome.

Dome is commonly associated with the monoclinic system.
\[ D\rightarrow II \]



Therefore, the correct matching is:
\[ A-III,\ B-I,\ C-IV,\ D-II \]
\[ \therefore Correct Answer is (B) \] Quick Tip: Rhombohedron is an important trigonal crystal form, while dome is commonly linked with monoclinic forms.

Concept:

Crystal systems are identified by their symmetry axes. Diad means two-fold axis, tetrad means four-fold axis, and triad means three-fold axis.



Step 1: Match Monoclinic.

Monoclinic crystal system has one diad axis.
\[ A\rightarrow IV \]



Step 2: Match Tetragonal.

Tetragonal crystal system has one tetrad axis.
\[ B\rightarrow III \]



Step 3: Match Orthorhombic.

Orthorhombic crystal system has three diad axes.
\[ C\rightarrow II \]



Step 4: Match Cubic.

Cubic crystal system has four triad axes.
\[ D\rightarrow I \]



Therefore, the correct matching is:
\[ A-IV,\ B-III,\ C-II,\ D-I \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Monoclinic has 1 diad, orthorhombic has 3 diads, tetragonal has 1 tetrad, and cubic has 4 triads.

Concept:

Twinning is the regular intergrowth of two or more crystals of the same mineral according to a definite crystallographic law.



Step 1: Match Geniculated twins.

Geniculated twins are commonly seen in rutile.
\[ A\rightarrow II \]



Step 2: Match Cruciform twins.

Cruciform twins are characteristic of staurolite.
\[ B\rightarrow I \]



Step 3: Match Butterfly twins.

Butterfly twins are associated with calcite.
\[ C\rightarrow IV \]



Step 4: Match Arrow head twins.

Arrow head twins are commonly shown by gypsum.
\[ D\rightarrow III \]



Therefore, the correct matching is:
\[ A-II,\ B-I,\ C-IV,\ D-III \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Cruciform twinning is typical of staurolite, while arrow-head twinning is common in gypsum.

Concept:

Different optical mineral properties are observed under different light conditions in a polarizing microscope.



Step 1: Match Cleavage.

Cleavage is commonly observed in plane polarized light.
\[ A\rightarrow I \]



Step 2: Match Twinkling.

Twinkling is observed in ordinary light conditions in optical mineralogy.
\[ B\rightarrow II \]



Step 3: Match Twinning.

Twinning is clearly observed under crossed nicols because different twin lamellae show different extinction positions.
\[ C\rightarrow III \]



Step 4: Match Dispersion.

Dispersion is studied with convergent light in interference figures.
\[ D\rightarrow IV \]



Therefore, the correct matching is:
\[ A-I,\ B-II,\ C-III,\ D-IV \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Cleavage is commonly seen in plane polarized light, while twinning is best observed under crossed nicols.

Concept:

Optical behaviour of isotropic and anisotropic minerals is represented by wave fronts and wave surfaces.



Step 1: Isotropic wave front.

In isotropic media, light travels with equal velocity in all directions. The wave front is circular.
\[ A\rightarrow IV \]



Step 2: Isotropic wave surface.

In three-dimensional representation, the isotropic wave surface is a sphere.
\[ B\rightarrow II \]



Step 3: Anisotropic wave front.

In anisotropic media, light velocity differs with direction. The wave front becomes elliptical.
\[ C\rightarrow I \]



Step 4: Anisotropic wave surface.

The three-dimensional wave surface in anisotropic minerals is ellipsoidal.
\[ D\rightarrow III \]



Therefore, the correct matching is:
\[ A-IV,\ B-II,\ C-I,\ D-III \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Isotropic wave surface is spherical, while anisotropic wave surface is ellipsoidal.

Concept:

The Earth's internal structure is divided into layers such as lithosphere, mantle and core. Each has an approximate average thickness.



Step 1: Match Lithosphere.

The lithosphere has an approximate average thickness of about:
\[ 105\ km \]
\[ A\rightarrow II \]



Step 2: Match Moho.

Moho represents the Mohorovicic discontinuity zone and is matched with:
\[ 2\ km \]
\[ B\rightarrow I \]



Step 3: Match Core.

The core has an approximate thickness of about:
\[ 3500\ km \]
\[ C\rightarrow IV \]



Step 4: Match Mantle.

The mantle extends to about:
\[ 2900\ km \]
\[ D\rightarrow III \]



Therefore, the correct matching is:
\[ A-II,\ B-I,\ C-IV,\ D-III \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Mantle thickness is approximately \(2900\ km\), while the core is about \(3500\ km\) thick.

Concept:

Folds are classified according to geometry, axial surface, limb attitude and development history.



Step 1: Match Polyclinal folds.

Polyclinal folds are folds with variable axial surfaces.
\[ A\rightarrow II \]



Step 2: Match Fan folds.

Fan folds are folds in which both limbs may be overturned, giving a fan-like geometry.
\[ B\rightarrow IV \]



Step 3: Match Conjugate folds.

Conjugate folds are folds in which axial surfaces dip towards each other.
\[ C\rightarrow III \]



Step 4: Match Cross folds.

Cross folds are produced by more than one phase or step of folding.
\[ D\rightarrow I \]



Therefore, the correct matching is:
\[ A-II,\ B-IV,\ C-III,\ D-I \]
\[ \therefore Correct Answer is (D) \] Quick Tip: Fan folds commonly have overturned limbs, while cross folds develop through more than one folding phase.

Concept:

Joints are fractures in rocks along which there is no significant displacement. They may form due to residual stress, tension, contraction or compression.



Step 1: Match Sheet joints.

Sheet joints commonly develop due to unloading or release of residual stress.
\[ A\rightarrow II \]



Step 2: Match Extension joints.

Extension joints form due to tensional stress.
\[ B\rightarrow IV \]



Step 3: Match Columnar joints.

Columnar joints commonly develop due to contraction during cooling of lava or igneous bodies.
\[ C\rightarrow I \]



Step 4: Match Conjugate joints.

Conjugate joints are commonly related to compressional stress conditions.
\[ D\rightarrow III \]



Therefore, the correct matching is:
\[ A-II,\ B-IV,\ C-I,\ D-III \]
\[ \therefore Correct Answer is (C) \] Quick Tip: Sheet joints are related to unloading or residual stress, while columnar joints are related to contraction during cooling.

Concept:

Igneous rocks show different textures depending on their cooling history, mineral composition and crystallization pattern.



Step 1: Match Ophitic texture.

Ophitic texture is commonly found in dolerite, where pyroxene encloses plagioclase laths.
\[ A\rightarrow II \]



Step 2: Match Trachytoid texture.

Trachytoid texture is commonly associated with syenite due to flow arrangement of tabular feldspar crystals.
\[ B\rightarrow I \]



Step 3: Match Myrmekite texture.

Myrmekite is an intergrowth texture commonly seen in granitic rocks.
\[ C\rightarrow IV \]



Step 4: Match Glomeroporphyritic texture.

Glomeroporphyritic texture is commonly associated with basalt, where phenocrysts occur in clusters.
\[ D\rightarrow III \]



Therefore, the correct matching is:
\[ A-II,\ B-I,\ C-IV,\ D-III \]
\[ \therefore Correct Answer is (C) \] Quick Tip: Ophitic texture is typical of dolerite, and myrmekite texture is commonly associated with granite.

Concept:

Superficial deposits are classified according to their origin and mode of transport. Some are residual, while others are transported by mass wasting, mudflow or flash flow.



Step 1: Match Deluvium.

Deluvium is matched with residual products formed by breakdown of primary rocks in the given classification.
\[ A\rightarrow II \]



Step 2: Match Eluvium.

Eluvium is matched with residual products formed by breakdown of mobile rocks in the given list.
\[ B\rightarrow III \]



Step 3: Match Proluvium.

Proluvium is commonly associated with sediments deposited by mudflows and flash flows.
\[ C\rightarrow IV \]



Step 4: Match Colluvium.

Colluvium is commonly formed by mass wasting on slopes.
\[ D\rightarrow I \]



Therefore, the correct matching is:
\[ A-II,\ B-III,\ C-IV,\ D-I \]
\[ \therefore Correct Answer is (A) \] Quick Tip: Colluvium is related to mass wasting, while proluvium is related to mudflow and flash-flow deposits.

Concept:

Important mineral resources are associated with specific mining regions in India.



Step 1: Match Copper.

Khetri in Rajasthan is famous for copper deposits.
\[ A\rightarrow IV \]



Step 2: Match Lead and zinc.

Zawar in Rajasthan is known for lead and zinc deposits.
\[ B\rightarrow III \]



Step 3: Match Iron.

Bastar region is associated with iron ore deposits.
\[ C\rightarrow II \]



Step 4: Match Fluorite.

Ambadongar is known for fluorite deposits.
\[ D\rightarrow I \]



Therefore, the correct matching is:
\[ A-IV,\ B-III,\ C-II,\ D-I \]
\[ \therefore Correct Answer is (C) \] Quick Tip: Remember: Khetri--Copper, Zawar--Lead and Zinc, Bastar--Iron, and Ambadongar--Fluorite.

Concept:

Mineral and energy resources are often associated with particular stratigraphic units and geological provinces.



Step 1: Match Copper and iron.

Singhbhum is well known for copper and iron mineralization.
\[ A\rightarrow II \]



Step 2: Match Petroleum.

Barail Group is associated with petroleum-bearing sequences in northeastern India.
\[ B\rightarrow IV \]



Step 3: Match Coal.

Damuda sequence is famous for coal-bearing formations.
\[ C\rightarrow I \]



Step 4: Match Bauxite.

Bauxite is associated with Eastern Ghat Khondalite terrain.
\[ D\rightarrow III \]



Therefore, the correct matching is:
\[ A-II,\ B-IV,\ C-I,\ D-III \]
\[ \therefore Correct Answer is (C) \] Quick Tip: Damuda is associated with coal, Singhbhum with copper and iron, Barail with petroleum, and Eastern Ghat Khondalite with bauxite.