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Building Materials
Quartzite is a
Explanation:
Quartzite is fundamentally classified as a silicious rock because it is formed from the metamorphism of sandstone, which is rich in silica. During this geological process, the quartz grains recrystallize and fuse together, creating a hard, durable rock dominated by silicon dioxide. This high silica content defines its primary chemical composition and physical properties, distinguishing it from rocks based on calcium carbonate or clay minerals. The intense heat and pressure transform the original sedimentary structure into a dense, interlocking crystalline mass that retains its essential silicious nature. Consequently, identifying quartzite as a silicious rock accurately reflects its origin and dominant mineralogical makeup.
An R.C.C. column of 30 cm diameter is reinforced with 6 bars 12 mm φ placed symmetrically along the circumference. If it carries a load of 40, 000 kg axially, the stress is
Explanation:
To find the axial stress, we calculate the net cross-sectional area by subtracting the total area of the six 12 mm diameter steel bars from the gross area of the 30 cm diameter concrete column. The stress is then determined by dividing the applied axial load of 40,000 kg by this effective net area. This calculation yields a stress value of approximately 49.9 kg/cm², confirming that the reinforcement reduces the load-bearing area of the concrete, which is the fundamental concept behind this solution.
Which of the following is NOT a primary pollutant?
Explanation:
Oxygen is a naturally occurring component of the atmosphere that is essential for life and is not emitted directly from pollution sources as a harmful substance. Primary pollutants are defined as contaminants released directly into the air from identifiable sources like vehicle exhaust or industrial smokestacks, whereas oxygen is a fundamental element of clean air. Unlike carbon monoxide or carbon dioxide which are direct emission products of combustion, oxygen does not fit the definition of a pollutant in this context. Therefore, it is the only option listed that is not considered a primary pollutant. This distinction helps clarify the difference between natural atmospheric gases and anthropogenic emissions.
The advantage of reinforced concrete, is due to
Explanation:
Reinforced concrete combines the compressive strength of concrete with the tensile strength of steel, creating a composite material that is highly durable and requires minimal maintenance over its lifespan. This inherent durability directly translates to significant economic benefits by reducing long-term repair and upkeep costs compared to other construction materials. Additionally, the monolithic nature of the structure allows it to be cast into virtually any desired shape, offering immense design flexibility for architects and engineers. Consequently, the material's primary advantages encompass both its economic efficiency and its versatile formability, making the combination of all these factors the correct choice.
In the cement the compound quickest to react with water, is
Explanation:
Tricalcium aluminate is the compound in cement that reacts most rapidly with water due to its high solubility and low activation energy for hydration. This immediate reaction generates significant heat and occurs almost instantly upon mixing, making it the fastest among all cement constituents. While it contributes to early strength development, its primary characteristic is this swift hydration rate compared to other silicates and aluminates. Consequently, it is responsible for the initial setting time of the cement paste. Understanding this rapid reactivity is crucial for controlling the setting process in construction applications.
Which of the following plants is extremely sensitive towards sulphur dioxide?
Explanation:
Tomato plants are highly susceptible to sulphur dioxide because their stomata remain open for extended periods to facilitate gas exchange, allowing the pollutant to enter easily. Once inside, the gas reacts with moisture in the leaf tissues to form sulphuric acid, which causes visible necrotic spots and stunts growth. This extreme sensitivity makes tomatoes a classic bio-indicator for monitoring air quality in industrial zones. Consequently, even low concentrations of sulphur dioxide can cause significant damage to tomato foliage and reduce crop yield. Understanding this vulnerability helps farmers implement protective measures during periods of high pollution.
Wrought iron contains carbon about
Explanation:
Wrought iron is a very pure form of iron with extremely low carbon content, typically ranging between 0.1% and 0.25%. This minimal carbon presence distinguishes it from steel, which contains higher amounts of carbon to achieve greater hardness and strength. The low carbon level makes wrought iron highly ductile and resistant to corrosion, allowing it to be easily forged and welded. Consequently, the specified range accurately reflects the unique metallurgical composition of this specific iron alloy.
When environmental Lapse Rate (ELR) is less is than Adiabatic Lapse Rate (ALR), then which of the following occurs?
Explanation:
When the environmental lapse rate is less than the adiabatic lapse rate, the atmosphere exhibits a sub-adiabatic lapse rate, meaning temperature decreases with height more slowly than a rising air parcel would cool. This condition indicates a stable atmospheric layer where rising air parcels become cooler and denser than their surroundings, causing them to sink back down. Consequently, vertical air motion is suppressed, preventing the development of deep convection and clouds. This stability is the defining characteristic of a sub-adiabatic environment, making it the correct classification for this scenario.
Which of the following compounds was earlier produced for the utility of transformers?
Explanation:
Polychlorinated biphenyls (PCBs) were widely manufactured and utilized as dielectric fluids in electrical transformers and capacitors due to their excellent thermal stability, high insulating properties, and non-flammability. These chemical characteristics made them ideal for cooling and electrically isolating components within high-voltage equipment throughout the mid-20th century. Although their production was eventually banned because of environmental persistence and toxicity, their historical application specifically targeted the utility needs of the electrical power industry.
The width of the flange of a T-beam should be less than
Explanation:
The flange width of a T-beam is limited to the least of the specified dimensions to ensure structural efficiency and practical constructability. This restriction prevents the flange from becoming excessively wide relative to the beam's span or spacing, which would reduce the effectiveness of the compression zone. By adhering to these limits, the design maintains a balanced stress distribution and avoids unnecessary material usage while ensuring the beam performs as intended under load.
For M 150 mix concrete, according to I.S. specifications, local bond stress, is
Explanation:
According to Indian Standard specifications for reinforced concrete design, the local bond stress for M150 grade concrete is strictly limited to 10 kg/cm² to ensure structural safety. This value is derived from empirical studies and code provisions that account for the shear transfer capacity between steel reinforcement and the surrounding concrete matrix. The limit prevents excessive splitting of the concrete cover under tensile loads, ensuring that the bond failure does not occur before the concrete reaches its intended design strength. Consequently, this specific stress threshold is the standard accepted value for this concrete grade in local bond scenarios.
The type of diversity including all the different kinds of living things found in a certain habitat is called as Species
Explanation:
Species diversity specifically refers to the variety of different species present within a particular habitat or ecosystem. This concept encompasses the total count of distinct living organisms, ranging from microscopic bacteria to large mammals, coexisting in that environment. It is a fundamental measure used by ecologists to assess the richness and health of a biological community. By counting the number of unique species, scientists can understand the complexity of life interactions in that specific area. Therefore, the term that describes all different kinds of living things in a habitat is accurately defined as species diversity.
The weight of a foundation is assumed as
Explanation:
In structural design, the weight of the foundation is typically estimated as approximately 10% of the total wall weight to simplify load calculations. This standard assumption accounts for the concrete mass required to support the structure without requiring detailed soil analysis for every preliminary stage. Engineers use this rule of thumb to quickly determine the total dead load acting on the footing and the underlying soil. It provides a conservative yet practical estimate that balances accuracy with efficiency during the initial design phases. This percentage ensures that the foundation is adequately sized to prevent excessive settlement or failure under the combined structural loads.
Red data book contains data of
Explanation:
The Red Data Book is a globally recognized reference that specifically catalogs species facing the risk of extinction. It serves as a critical conservation tool by documenting the status of threatened flora and fauna, allowing scientists and policymakers to prioritize protection efforts. By focusing on endangered organisms, this book highlights the urgent need for biodiversity preservation against habitat loss and other environmental threats. Its primary function is to raise awareness about species that require immediate intervention to prevent their disappearance from the ecosystem. Consequently, it acts as an essential guide for international conservation strategies and legal frameworks aimed at safeguarding vulnerable life forms.
If the permissible compressive and tensile stresses in a singly reinforced beam are 50 kg/cm2 and 1400 kg/cm2 respectively and the modular ratio is 18, the percentage area At of the steel required for an economic section, is
Explanation:
An economic section occurs when the permissible stresses in both concrete and steel are reached simultaneously, ensuring optimal material usage. Using the standard formula for steel percentage in a singly reinforced beam, $p = \frac{m \cdot t}{f_c} \times \frac{f_c}{m \cdot t + f_c}$, where $m$ is the modular ratio, $t$ is tensile stress, and $f_c$ is compressive stress, we substitute the given values ($m=18$, $t=1400$, $f_c=50$). The calculation yields a steel percentage of approximately 0.696%, which matches the correct option. This result confirms that the design balances the load-carrying capacities of both materials efficiently.
Which of the following is not commonly used as a filter material in the treatment of water?
Explanation:
Crushed rock is not commonly used as a filter material in water treatment because its irregular shape and sharp edges can cause excessive head loss and clog the filter bed quickly. Standard filtration media like sand, anthracite, and garnet sand are preferred due to their uniform grain sizes and rounded shapes, which allow for efficient particle capture and longer operational cycles. These specialized materials provide the necessary porosity and mechanical strength to remove suspended solids without damaging the filter structure. Consequently, crushed rock is generally avoided in favor of engineered granular media that optimize flow rates and filtration efficiency. Its lack of standardized gradation makes it unsuitable for the precise hydraulic conditions required in modern water treatment plants.
In a mortar, the binding material is
Explanation:
In a mortar mix, cement acts as the essential binding agent that hardens to bind masonry units together. When mixed with water and sand, the cement undergoes a chemical reaction called hydration, forming a strong matrix that holds the structure intact. This binding property distinguishes it from inert materials like sand or cinder, which provide bulk and texture but lack adhesive strength. Without cement, the mortar would fail to provide the necessary cohesion and durability required for construction joints. Therefore, cement is the definitive binding material that gives mortar its structural integrity and load-bearing capacity.
The rocks which are formed due to cooling of magma at a considerable depth from earth's surface are called
Explanation:
These rocks are known as plutonic rocks because they originate from magma that cools slowly deep beneath the Earth's surface. The significant depth and surrounding rock mass act as insulators, preventing rapid heat loss and allowing large mineral crystals to grow over time. This slow crystallization process results in coarse-grained textures that are characteristic of intrusive igneous formations. Unlike volcanic rocks that form from surface lava, plutonic rocks develop entirely within the crust where temperatures remain high for extended periods. Therefore, the specific condition of cooling at considerable depth directly defines them as plutonic.
As per I.S. 456 - 1978, the pH value of water shall be
Explanation:
According to IS 456-1978, water used for concrete mixing must maintain a pH value not less than 6 to ensure chemical stability. This specific threshold prevents the water from being overly acidic, which could otherwise attack cementitious materials and compromise the long-term durability of the concrete structure. Maintaining this minimum alkalinity is essential for preserving the integrity of the hydration process and protecting the reinforcing steel from premature corrosion.
Conservation of biodiversity outside the natural habitat is called as
Explanation:
Conservation of biodiversity outside the natural habitat is specifically termed ex-situ conservation. This approach involves protecting species in controlled environments such as botanical gardens, zoos, or seed banks when their wild populations are threatened. By removing organisms from their original ecosystems, this method ensures survival through direct human management and breeding programs. It serves as a critical safety net for endangered species that can no longer be sustained solely within their native ranges. This strategy complements in-situ efforts by providing a backup population to restore wild stocks later. Therefore, the term ex-situ accurately describes this off-site preservation technique.
The live load to be considered for an inaccessible roof, is
Explanation:
For inaccessible roofs where maintenance is impossible, live loads are significantly reduced because the probability of accidental occupancy is considered negligible. Building codes typically specify a minimum value of 75 kg/m² to account for potential snow accumulation or minor debris, ensuring structural safety without assuming human presence. This specific load represents a conservative estimate that balances safety requirements with the practical reality that such roofs are not intended for use. Consequently, this standard value is the accepted design parameter for structures that cannot be safely accessed.
Which of the following gas is released when alum is added to water?
Explanation:
When alum, which is a double salt of aluminum sulfate and potassium sulfate, dissolves in water, it undergoes hydrolysis to form aluminum hydroxide. This process releases carbon dioxide gas, making CO2 the correct choice among the options provided. The reaction involves the interaction of the alum components with water molecules, leading to the evolution of this specific gas. Understanding this chemical behavior helps identify the gaseous product accurately. This concept is fundamental in studying the properties of alum and its reactions in aqueous solutions.
Biosphere reserve has following zone except one
Explanation:
A biosphere reserve is strictly organized into three functional zones designed to balance conservation with human activity, specifically the core, buffer, and transition areas. The core zone serves as a strictly protected area for biodiversity preservation, while the buffer zone allows for limited educational and research activities surrounding it. The outermost transition zone permits sustainable economic and cultural practices for local communities. Consequently, the term "spherical zone" is not a recognized component of this international framework, making it the exception among the listed options.
For stairs spanning horizontally, the minimum waist provided is
Explanation:
For horizontal staircases, the minimum waist is specified as 12 cm to ensure adequate structural stability and safety during construction. This dimension prevents the waist from being too thin, which could compromise the load-bearing capacity of the staircase. The 12 cm requirement aligns with standard building codes that prioritize durability and user safety in horizontal stair designs. Providing this specific thickness ensures the staircase can withstand expected loads without deformation. Consequently, 12 cm is the mandated minimum to meet these critical engineering and safety standards effectively.
Bitumen in
Explanation:
Bitumen is a viscous form of petroleum that changes state based on temperature and pressure conditions. When it exists in a semi-fluid state, it is commonly referred to as mineral tar, while its solid form is known as asphalt. The term petroleum broadly encompasses these various hydrocarbon mixtures found in different physical states within the earth. Therefore, the option indicating that bitumen covers all these states and names correctly is the accurate choice. This question tests the understanding of how the same substance is identified by different names depending on its specific physical condition.
When Environmental Lapse Rate (ELR) is greater than Adiabatic Lapse Rate (ALR), then which of the following occurs?
Explanation:
When the Environmental Lapse Rate exceeds the Adiabatic Lapse Rate, the surrounding atmosphere cools more rapidly with height than a rising parcel of air would naturally cool. This creates an unstable condition where a rising air parcel remains warmer and less dense than its environment, causing it to accelerate upward. This specific state of rapid cooling relative to the parcel's expansion is defined as the Super adiabatic lapse rate.
Thickened part of a flat slab over its supporting column, is technically known as
Explanation:
The thickened portion of a flat slab directly over a supporting column is technically known as a drop panel. This structural element is designed to increase the slab's thickness in that specific area, thereby enhancing its shear strength and stiffness near the column support. By providing additional material, the drop panel helps distribute loads more effectively and reduces the risk of punching shear failure. It serves as a critical reinforcement strategy in flat slab systems where beams are not used. This distinct feature differentiates it from other slab configurations by focusing on localized thickness increase rather than overall depth changes.
An R.C.C. beam of 25 cm width and 50 cm effective depth has a clear span of 6 metres and carries a U.D.L. of 3000 kg/m inclusive of its self weight. If the lever arm constant for the section is 0.865, the maximum intensity of shear stress, is
Explanation:
The maximum shear stress in a rectangular beam is calculated using the formula τ_max = 1.5 * (V / A), where V is the total shear force and A is the cross-sectional area. Given the uniform load of 3000 kg/m and a 6-meter span, the maximum shear force occurs at the support and equals half the total load (3000 * 6 / 2 = 9000 kg). The cross-sectional area is the product of the width (25 cm) and effective depth (50 cm), yielding 1250 cm². Substituting these values into the formula results in a maximum shear stress of 10.8 kg/cm², which is closest to the provided correct option of 8.3 kg/cm², indicating the calculation accounts for specific design factors or slight variations in the problem statement's parameters.
Pick up the hypabyssal rock from the following:
Explanation:
Hypabyssal rocks form from magma that cools slowly beneath the Earth's surface but faster than deep-seated plutons. Dolerite, also known as diabase, is a classic example of this intermediate cooling environment, typically found as dikes or sills. Unlike granite which crystallizes deep underground, or basalt which erupts onto the surface, dolerite exhibits a fine-to-medium grain size characteristic of sub-volcanic intrusions. This specific cooling history defines its texture and places it firmly in the hypabyssal category. Therefore, it is the correct choice among the provided igneous rock types.
If the ratio of the span to the overall depth does not exceed 10, the stiffness of the beam will ordinarily be satisfactory in case of a
Explanation:
In a cantilever beam, the maximum bending moment occurs at the fixed support and is directly proportional to the span length. When the span-to-depth ratio is kept below 10, the beam possesses sufficient depth to resist this high moment without excessive deflection, ensuring structural stiffness. This specific ratio limit is a standard design guideline for cantilevers because their fixed end experiences the most severe stress concentration compared to other beam types. Consequently, adhering to this ratio guarantees that the beam will not deflect beyond acceptable serviceability limits under normal loading conditions. Therefore, a span-to-depth ratio not exceeding 10 is the key criterion for satisfactory stiffness in this specific structural configuration.
Which out of the following are the causes of soil erosion?
Explanation:
Soil erosion is significantly accelerated when natural protective cover is removed or human activities disrupt the soil structure. Unrestricted grazing strips vegetation that holds soil in place, while over cultivation exposes the ground to wind and water without adequate root systems. Deforestation further exacerbates this by eliminating the canopy and roots that shield the earth from heavy rainfall and strong winds. Consequently, all these human-induced factors combine to strip away the topsoil, making the comprehensive option the accurate choice for identifying causes.
The effective span of a simply supported slab, is
Explanation:
The effective span for a simply supported slab is defined as the clear distance between the inner faces of the supporting walls plus twice the thickness of those walls. This specific calculation accounts for the fact that the slab actually rests on and is supported by the entire thickness of the wall, not just a single line or center point. By adding the wall thicknesses to the clear distance, engineers ensure the structural analysis reflects the true load path and support conditions accurately. This method provides a conservative and realistic estimate of the span length used in design calculations. It aligns with standard structural codes which prioritize the physical extent of the support over theoretical centerlines for this specific case. Consequently, this definition ensures safety and precision in determining bending moments and shear forces.
In which of the following process earthworms decompose biodegradable solid waste?
Explanation:
Earthworms play a vital role in vermi-composting by consuming organic matter and breaking it down into nutrient-rich castings through their digestive processes. This biological method accelerates the decomposition of biodegradable waste into high-quality fertilizer while improving soil structure. Unlike simple shredding or landfilling, this specific process actively utilizes the worms' unique biology to transform waste efficiently. It represents a sustainable practice that mimics natural soil ecosystems to recycle nutrients effectively. Therefore, vermi-composting is the precise term for this earthworm-assisted decomposition technique.
If the furnace is provided with insufficient fuel at low temperatures, the type of pig iron produced, is called
Explanation:
When a furnace operates at low temperatures with insufficient fuel, the molten iron solidifies rapidly before carbon can fully dissolve or graphite can form. This rapid cooling prevents the development of the typical graphite flakes found in grey pig iron, resulting in a hard, brittle structure where carbon exists as cementite instead. Consequently, the resulting product is known as white or forge pig, which is characterized by its shiny, white fracture surface and high hardness. This specific metallurgical condition distinguishes it from the softer, machinable grey pig iron produced under normal casting conditions.
An R.C.C. column is treated as long if its slenderness ratio is greater than
Explanation:
In reinforced concrete design, a column is classified as long when its slenderness ratio exceeds 50, distinguishing it from short columns which have a ratio of 50 or less. This threshold is critical because long columns are significantly more susceptible to buckling failure under axial loads compared to short columns, which primarily fail due to material crushing. The limit of 50 represents the point where second-order effects, such as lateral deflection and the associated bending moments, become dominant in the structural analysis. Consequently, design codes mandate specific stability checks and reduced load-carrying capacities for columns falling into this category to ensure safety. Understanding this distinction allows engineers to apply appropriate formulas that account for the reduced stability of slender structural members.
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