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Question 1
ప్రశ్న 1
During a geological investigation for a major foundation, an engineer must distinguish a mineral from a rock. Which statement correctly describes a mineral in the conventional geological sense?
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Explanation:
A mineral is generally defined as a naturally occurring inorganic solid possessing an ordered internal structure and characteristic chemical composition. Its composition may vary within limits allowed by its crystal structure. Quartz and calcite are examples of minerals. A rock is a naturally occurring geological material that may contain one mineral or an assemblage of minerals. Distinguishing minerals from rocks helps engineers interpret material composition, weathering susceptibility and construction performance.
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Question 2
ప్రశ్న 2
A light-coloured mineral in a granite sample scratches ordinary glass, has Mohs hardness approximately 7 and shows curved conchoidal fracture without prominent cleavage. Which mineral is most strongly indicated?
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Explanation:
Quartz has a chemical composition of SiO2 and a Mohs hardness of approximately 7. It is harder than ordinary glass and commonly displays conchoidal fracture. Quartz does not possess prominent cleavage planes. Calcite and gypsum are considerably softer, while muscovite has excellent sheet-like cleavage. Quartz is an important constituent of many durable rocks and natural sands, although the suitability of an aggregate depends on more than the presence of quartz.
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Question 3
ప్రశ్న 3
During petrographic examination of a granitic building stone, a mineral shows Mohs hardness close to 6 and two prominent cleavage directions intersecting approximately at right angles. Which identification is most appropriate?
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Explanation:
Feldspars are common rock-forming aluminosilicate minerals in granite and several other igneous rocks. Their Mohs hardness is commonly around 6. They possess two prominent cleavage directions intersecting approximately at right angles. Quartz lacks prominent cleavage and commonly produces conchoidal fracture. Feldspar identification is relevant because chemical weathering can alter these minerals to clay-rich products and affect rock durability.
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Question 4
ప్రశ్న 4
A field geologist observes fine, approximately parallel striations on a cleavage surface of a light-coloured feldspar crystal. Which interpretation is most appropriate?
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Explanation:
Plagioclase feldspars commonly exhibit fine parallel striations on certain cleavage surfaces. These markings are associated with repeated crystal twinning. They can help distinguish plagioclase from potassium feldspar during hand-specimen examination. Plagioclase minerals are important constituents of many igneous and metamorphic rocks. Their identification contributes to rock classification and assessment of weathering products.
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Question 5
ప్రశ్న 5
A mineral in a metamorphic rock can be separated into thin, flexible sheets along one highly developed cleavage direction. Which mineral group and associated property are indicated?
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Explanation:
Micas are sheet silicate minerals characterized by excellent cleavage along their basal planes. Muscovite commonly forms light-coloured sheets, while biotite is generally dark-coloured. Their crystal structures permit separation into thin flakes. This property is useful for field identification and has engineering implications where mica-rich materials develop weak or preferential separation surfaces. The concentration, orientation and condition of mica must be considered when assessing rock masses and aggregates.
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Question 6
ప్రశ్న 6
A pale mineral from a sedimentary building-stone deposit has Mohs hardness approximately 3 and effervesces readily when dilute hydrochloric acid is applied to a fresh surface. Which mineral is most likely present?
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Explanation:
Calcite is calcium carbonate with chemical formula CaCO3. It has Mohs hardness approximately 3 and reacts readily with dilute hydrochloric acid, releasing carbon dioxide. The reaction commonly produces visible effervescence. Calcite is the principal mineral in many limestones and marbles. Its acid susceptibility must be considered when selecting carbonate building stones for chemically aggressive environments.
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Question 7
ప్రశ్న 7
A carbonate mineral resembles calcite but reacts only weakly with cold dilute hydrochloric acid on an intact surface and reacts more clearly when powdered. Which interpretation is most appropriate?
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Explanation:
Dolomite has the chemical composition CaMg(CO3)2. It resembles calcite in several physical characteristics but commonly responds less vigorously to cold dilute hydrochloric acid. Powdering the specimen increases the exposed surface area and can make its acid reaction more noticeable. The test is a useful preliminary distinction between calcite and dolomite. Engineering assessment of dolomitic rock should also consider texture, impurities, weathering and relevant durability or aggregate-reactivity tests.
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Question 8
ప్రశ్న 8
An unknown mineral scratches apatite, which has Mohs hardness 5, but is scratched by orthoclase feldspar, which has Mohs hardness 6. Which conclusion is correct?
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Explanation:
A harder mineral can generally scratch a softer mineral under suitable testing conditions. Because the unknown scratches apatite, it is harder than the reference mineral of hardness 5. Because orthoclase scratches the unknown, the unknown is softer than hardness 6. Its Mohs hardness therefore lies approximately between 5 and 6. The Mohs scale ranks relative scratch resistance and does not represent equal increments in absolute hardness.
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Question 9
ప్రశ్న 9
A nonporous quartz specimen has volume 0.002 m3. Its specific gravity is 2.65 relative to water of density 1000 kg/m3. What is the mass of the specimen?
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Explanation:
Specific gravity is the ratio of material density to the density of the reference substance. The quartz density is therefore 2.65(1000) = 2650 kg/m3. Mass is obtained by multiplying density by volume. Thus the specimen mass is 2650(0.002) = 5.30 kg. The calculation assumes a nonporous specimen so that the specified volume represents the volume occupied by the mineral.
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Question 10
ప్రశ్న 10
An engineer observes smooth, repeated planar breakage surfaces in one mineral and irregular curved breakage surfaces in another. Which statement correctly distinguishes cleavage from fracture?
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Explanation:
Cleavage develops where minerals preferentially separate along particular crystallographic planes. Its quality and directions reflect the arrangement and bonding of atoms within the crystal. Fracture occurs where breakage does not follow cleavage planes. Quartz commonly exhibits conchoidal fracture, while mica demonstrates excellent basal cleavage. Recognizing these properties helps in mineral identification and provides insight into potential particle breakage characteristics.
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Question 11
ప్రశ్న 11
A dark, metallic-looking mineral in a rock specimen produces a reddish-brown streak when tested appropriately. Which mineral is strongly indicated by this diagnostic property?
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Explanation:
Hematite is an iron oxide mineral with composition Fe2O3. Its external appearance can range from earthy red to shiny dark grey or metallic forms. Despite this variation in appearance, hematite commonly produces a reddish-brown streak. Streak is the colour of the powdered mineral and may be more reliable than external colour alone. Hematite identification can assist interpretation of iron-rich rocks, weathering products and mineral constituents in construction materials.
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Question 12
ప్రశ్న 12
Which pairing correctly identifies the typical lustre of quartz and pyrite?
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Explanation:
Lustre describes how a mineral surface reflects light. Quartz commonly exhibits vitreous or glass-like lustre. Pyrite generally shows metallic lustre and a brass-yellow appearance on fresh surfaces. Their appearances therefore provide useful preliminary identification clues. Lustre should nevertheless be combined with hardness, streak, cleavage and other observations because weathering and surface condition can modify visual appearance.
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Question 13
ప్రశ్న 13
A transparent mineral breaks readily along three cleavage directions that are not mutually perpendicular, producing rhombohedral fragments. Which identification is most appropriate?
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Explanation:
Calcite commonly displays excellent cleavage in three directions. The angles between its cleavage planes are not right angles. The resulting fragments may have characteristic rhombohedral shapes. Halite instead exhibits cubic cleavage with three mutually perpendicular directions. Cleavage geometry, together with hardness and acid reaction, helps distinguish these minerals during geological investigations.
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Question 14
ప్రశ్న 14
Two dark rock-forming silicate minerals are examined in hand specimens. Mineral X exhibits two cleavage directions intersecting at approximately 60 degrees and 120 degrees, whereas Mineral Y has two cleavage directions intersecting near 90 degrees. Which identification is most likely?
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Explanation:
Amphiboles such as hornblende commonly have two cleavage directions intersecting at approximately 56 degrees and 124 degrees. These are often described approximately as 60 degrees and 120 degrees in introductory identification. Pyroxenes generally possess two cleavage directions meeting near 90 degrees. Both mineral groups occur in many igneous and metamorphic rocks. Their distinction contributes to mineralogical identification and assessment of the composition and weathering behaviour of parent rocks.
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Question 15
ప్రశ్న 15
A granite exposed in a humid environment develops a softened weathered zone containing clay-rich products, although relatively fresh quartz grains remain identifiable. Which mineralogical process most directly explains this observation?
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Explanation:
Feldspars can undergo chemical alteration when exposed to water and suitable geochemical conditions. Hydrolysis is an important mechanism through which feldspar may produce clay minerals and dissolved constituents. Quartz is generally more resistant to many near-surface chemical weathering processes. Progressive feldspar alteration can weaken the interlocking fabric of a granitic rock. Engineering investigations should distinguish sound rock from weathered granite because bearing resistance, deformability and excavation behaviour may differ substantially.
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Question 16
ప్రశ్న 16
Two minerals occur in a newly exposed rock face: olivine and quartz. Under common moist, oxidizing surface conditions, which engineering interpretation of their relative chemical-weathering susceptibility is generally appropriate?
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Explanation:
Olivine is an iron-magnesium silicate that crystallizes under relatively high-temperature geological conditions. It can be susceptible to alteration and chemical weathering under common near-surface conditions. Quartz is generally more resistant in many such environments. The relative abundance of these minerals can therefore influence the long-term mineralogical changes occurring within a rock. Actual rock durability also depends on texture, fractures, permeability, climate and other constituent minerals.
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Question 17
ప్రశ్న 17
A foundation investigation identifies clay minerals of the smectite group, particularly sodium montmorillonite, in the near-surface soil. Which conclusion is most appropriate when compared with a soil dominated by kaolinite under otherwise comparable conditions?
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Explanation:
Smectite-group minerals contain structures that permit substantial hydration-related expansion. Sodium montmorillonite is particularly associated with pronounced swelling behaviour. Kaolinite generally exhibits much lower interlayer swelling under comparable conditions. The mineral assemblage therefore provides useful evidence of possible expansive-soil behaviour. Laboratory swelling tests, active-zone assessment and field moisture conditions are still needed before selecting a foundation solution.
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Question 18
ప్రశ్న 18
A proposed fine aggregate for structural concrete contains a significant proportion of free, flaky mica particles. Which engineering concern is most relevant?
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Explanation:
Mica commonly occurs as thin, plate-like particles because of its excellent basal cleavage. Excessive free mica in fine aggregate can influence particle packing and the water demand of concrete. It may also affect the bond between aggregate particles and the cementitious matrix. The severity depends on mica content, particle characteristics and concrete mix proportions. Aggregate suitability should be determined from appropriate characterization and performance testing rather than mineral presence alone.
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Question 19
ప్రశ్న 19
A site investigation finds substantial gypsum-bearing material within rock proposed for a water-retaining structure's foundation. Which concern is most directly relevant to the mineral's chemical characteristics?
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Explanation:
Gypsum is calcium sulfate dihydrate with chemical formula CaSO4·2H2O. It is appreciably more soluble in water than many common silicate rock-forming minerals. Dissolution can contribute to deterioration or loss of material in susceptible geological settings. Sulfate-bearing water may also be relevant to the durability of cementitious construction materials. Investigation should establish groundwater chemistry, geological conditions and the extent of potentially soluble material before design decisions are made.
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Question 20
ప్రశ్న 20
A crushed-rock source proposed for concrete aggregates contains visible pyrite grains. Which engineering assessment is most appropriate?
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Explanation:
Pyrite is an iron sulfide mineral with chemical formula FeS2. Under suitable conditions it can undergo oxidation in the presence of oxygen and water. The resulting products may include acidic and sulfate-bearing constituents. Such reactions can contribute to aggregate deterioration, staining or damage to adjacent cementitious material in susceptible situations. Petrographic examination and appropriate durability assessment are therefore justified when problematic sulfide minerals are identified in an aggregate source.
వివరణ:
Question 21
ప్రశ్న 21
A petrographic examination identifies highly strained quartz and cryptocrystalline silica in a proposed concrete aggregate. Which statement about alkali-silica reaction is technically most appropriate?
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Explanation:
Alkali-silica reaction involves susceptible siliceous constituents interacting with alkaline pore solution in concrete. Certain poorly crystalline, microcrystalline or highly strained forms of silica may be particularly relevant. Sufficient moisture is generally needed for damaging expansion to develop. The presence of quartz by itself does not establish that an aggregate will produce deleterious reaction. Petrographic findings should be interpreted alongside appropriate expansion testing and the proposed concrete exposure conditions.
వివరణ:
Question 22
ప్రశ్న 22
A dark, relatively dense mineral in a crushed-rock sample is strongly attracted to a hand magnet. Another iron-bearing mineral has a reddish-brown streak but does not exhibit the same strong magnetic response. Which pairing is most appropriate?
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Explanation:
Magnetite is an iron oxide mineral with formula Fe3O4 and commonly exhibits a strong magnetic response. Hematite is another iron oxide mineral with formula Fe2O3. Hematite is particularly recognized by its reddish-brown streak. These diagnostic properties can assist identification of iron-bearing accessory minerals in rocks. Their abundance may be relevant to mineral composition, density and assessment of particular construction-material sources.
వివరణ:
Question 23
ప్రశ్న 23
An idealized, completely solid mineral mixture contains 60% quartz and 40% feldspar BY SOLID VOLUME. Their specific gravities are 2.65 and 2.56 respectively. Assuming additive solid volumes and the same reference water density, what is the specific gravity of the combined mineral mixture?
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Explanation:
The question specifies volume fractions rather than mass fractions. For additive solid volumes, the mixture density is the volume-weighted average of the constituent densities. The corresponding specific gravity is 0.60(2.65) + 0.40(2.56). This gives 1.590 + 1.024 = 2.614, or approximately 2.61. The result describes the ideal solid mineral mixture and should not be confused with the bulk density of a porous rock containing voids.
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Question 24
ప్రశ్న 24
A polished calcite-rich limestone is proposed as external cladding for a structure exposed to frequent acidic industrial precipitation. Which material-selection judgement is most appropriate?
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Explanation:
Calcite is a carbonate mineral that reacts with acidic solutions. Calcite-rich limestone may therefore undergo progressive surface dissolution under sufficiently aggressive exposure conditions. Polishing does not fundamentally change the mineral's chemical composition. Loss of surface detail, roughening or other deterioration may occur depending on the environmental conditions. Selection of external building stone should consider mineralogy, water exposure, pollutant chemistry and long-term maintenance requirements.
వివరణ:
Question 25
ప్రశ్న 25
A quarry supplies crushed rock for an important reinforced-concrete water-retaining structure. Hand-specimen examination identifies quartz, feldspar, mica and occasional sulfide-bearing grains, but the rock also contains visible weathered patches. Which approach provides the most defensible aggregate-suitability assessment?
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Explanation:
Aggregate performance depends on the complete rock assemblage and its physical condition. Mineralogy can reveal weathering susceptibility, cleavage-related weaknesses and potentially deleterious constituents. Petrographic examination helps identify minerals, textures, alteration products and microcracks. Mechanical and durability tests provide additional evidence about performance under the intended conditions. A sound engineering decision integrates these findings with the applicable aggregate specifications and exposure requirements.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: B. A mineral is a naturally occurring, generally inorganic crystalline solid with a characteristic chemical composition, whereas a rock may contain one or more minerals. సమాధానం: B.
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Question 2 ప్రశ్న 2Answer: D. Quartz. సమాధానం: D.
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Question 3 ప్రశ్న 3Answer: A. Feldspar. సమాధానం: A.
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Question 4 ప్రశ్న 4Answer: C. The striations are characteristic of twinning commonly observed in plagioclase feldspar. సమాధానం: C.
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Question 5 ప్రశ్న 5Answer: B. Mica group with perfect basal cleavage. సమాధానం: B.
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Question 6 ప్రశ్న 6Answer: D. Calcite. సమాధానం: D.
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Question 7 ప్రశ్న 7Answer: A. The mineral may be dolomite, which generally shows a less vigorous cold dilute-acid reaction than calcite. సమాధానం: A.
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Question 8 ప్రశ్న 8Answer: C. Its hardness lies approximately between 5 and 6, and the Mohs scale is an ordinal rather than a linear measure of hardness. సమాధానం: C.
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Question 9 ప్రశ్న 9Answer: B. 5.30 kg. సమాధానం: B.
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Question 10 ప్రశ్న 10Answer: A. Cleavage involves preferential breakage along crystallographically controlled planes, whereas fracture describes breakage not following such cleavage planes. సమాధానం: A.
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Question 11 ప్రశ్న 11Answer: D. Hematite. సమాధానం: D.
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Question 12 ప్రశ్న 12Answer: C. Quartz — vitreous; pyrite — metallic. సమాధానం: C.
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Question 13 ప్రశ్న 13Answer: B. Calcite, which exhibits three prominent rhombohedral cleavage directions. సమాధానం: B.
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Question 14 ప్రశ్న 14Answer: A. X — amphibole; Y — pyroxene. సమాధానం: A.
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Question 15 ప్రశ్న 15Answer: D. Feldspars undergo chemical weathering, including hydrolysis, that can produce clay minerals and weaken the original rock fabric. సమాధానం: D.
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Question 16 ప్రశ్న 16Answer: C. Olivine is generally more susceptible to chemical weathering near the Earth's surface than quartz. సమాధానం: C.
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Question 17 ప్రశ్న 17Answer: A. Sodium montmorillonite generally exhibits greater water-induced swelling potential and requires assessment of possible foundation heave. సమాధానం: A.
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Question 18 ప్రశ్న 18Answer: D. Excessive mica may increase water demand and adversely affect aggregate-paste interaction, workability or hardened concrete properties. సమాధానం: D.
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Question 19 ప్రశ్న 19Answer: B. Gypsum is calcium sulfate dihydrate, and its dissolution and sulfate-bearing water can create durability or foundation-material concerns. సమాధానం: B.
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Question 20 ప్రశ్న 20Answer: C. Pyrite is an iron sulfide that can oxidize under suitable exposure conditions, potentially generating acidic or sulfate-bearing products and causing material deterioration. సమాధానం: C.
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Question 21 ప్రశ్న 21Answer: B. Certain forms of silica, including highly strained or finely crystalline forms, may be potentially reactive; their significance must be assessed with alkali availability, moisture and suitable aggregate testing. సమాధానం: B.
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Question 22 ప్రశ్న 22Answer: A. Strongly magnetic mineral — magnetite; reddish-brown-streak mineral — hematite. సమాధానం: A.
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Question 23 ప్రశ్న 23Answer: D. 2.61. సమాధానం: D.
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Question 24 ప్రశ్న 24Answer: C. Calcite-rich limestone may be vulnerable to acid-related surface dissolution, so exposure conditions and suitable protection or alternative materials should be assessed. సమాధానం: C.
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Question 25 ప్రశ్న 25Answer: B. Combine mineralogical and petrographic assessment with relevant physical, mechanical and durability tests, considering potentially harmful constituents and the intended exposure. సమాధానం: B.