Ion Exchange Phenomena: Cation Exchange Capacity (CEC), Anion Exchange Capacity (AEC) and Base Saturation - Physical Science

ICAR AIEEA PG 2024 - Physical Science (Q.82)

Assertion & Reason +4 −1

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R):

Assertion (A) : Cations adsorbed on soil colloids determine aggregate formation.

Reason (R) : Cations form electropositive links between electronegative soil particles.

In light of the above statements, choose the most appropriate answer from the options given below:

नीचे दो कथन दिए गए हैं, एक

अभिकथन : (Assertion A) और दूसरा कारण (Reason R) के रूप में अंकित है:

अभिकथन (A) : मृदा कोलाइड्स पर अधिशोषित धनायन समुच्चय निर्माण (aggregate formation) को निर्धारित करते हैं।

कारण (R) : धनायन ऋणात्मक रूप से आवेशित मृदा कणों के बीच विद्युत-धनात्मक संयोजन (electropositive links / cation bridges) बनाते हैं।

उपर्युक्त कथनों के आलोक में, नीचे दिए गए विकल्पों में से सबसे उपयुक्त उत्तर चुनें:

Both (A) and (R) are correct and (R) is the correct explanation of (A) (A) और (R) दोनों सही हैं और (R), (A) की सही व्याख्या है Both (A) and (R) are correct but (R) is NOT the correct explanation of (A) (A) और (R) दोनों सही हैं लेकिन (R), (A) की सही व्याख्या नहीं है (A) is correct but (R) is not correct (A) सही है लेकिन (R) सही नहीं है (A) is not correct but (R) is correct (A) सही नहीं है लेकिन (R) सही है

Assertion (A) is correct: The composition of exchangeable cations on clay surfaces directly controls whether soil particles flocculate into stable aggregates or disperse into single grains (e.g., $\text{Ca}^{2+}$ promotes aggregation, whereas $\text{Na}^+$ causes dispersion).
Reason (R) is correct and explains (A): Clay minerals and humic colloids carry permanent and pH-dependent net negative charges. Divalent and trivalent cations (such as $\text{Ca}^{2+}$, $\text{Mg}^{2+}$, and $\text{Al}^{3+}$) compress the diffuse double layer and form electrostatic bridges ('cation bridges') connecting the negative surfaces of adjoining clay plates and polyanionic organic macromolecules, drawing them together into floccules and water-stable aggregates.

अभिकथन (A) सही है: मृदा कोलाइड्स पर अधिशोषित विनिमेय धनायन यह निर्धारित करते हैं कि मृदा कण आपस में जुड़कर स्थिर समुच्चय (aggregates) बनाएंगे अथवा विक्षेपित (disperse) होकर बिखर जाएंगे (जैसे कैल्शियम $\text{Ca}^{2+}$ समुच्चय बनाता है, जबकि सोडियम $\text{Na}^+$ विक्षेपण करता है)।
कारण (R) सही है और (A) की सही व्याख्या करता है: क्ले और ह्यूमस कणों की सतह पर शुद्ध ऋणावेश होता है। द्विसंयोजी धनायन (विशेष रूप से $\text{Ca}^{2+}$) दो ऋणावेशित मृदा कणों के मध्य विद्युत-धनात्मक सेतु ('धनायन सेतु / Cation bridge') बनाते हैं और कणों के चारों ओर विद्युत दोहरी परत को संकुचित कर उन्हें पास लाते हैं, जिससे ऊर्णन (flocculation) और स्थिर समुच्चयों का निर्माण होता है।

अतः (A) और (R) दोनों सही हैं और (R), (A) की सही व्याख्या है।

Explanation not matching this question? क्या व्याख्या इस प्रश्न से मेल नहीं खा रही? Report Mismatch त्रुटि बताएं

ICAR AIEEA PG Physical Science 09 July 2023 (Shift 1) Paper (Q.88)

Match the Following +4 −1

Match List-I with List-II:

Choose the correct answer from the options given below:

सूची-I को सूची-II के साथ सुमेलित कीजिए:

नीचे दिए गए विकल्पों में से सही उत्तर का चयन कीजिए:

List - I सूची - I Theory / Concept proposed सिद्धांत / अवधारणा		List - II सूची - II Author वैज्ञानिक
A	Contact exchange संपर्क विनिमय (Contact exchange)	I	Bray ब्रे (Bray)
B	Air capacity of soil मृदा की वायु क्षमता (Air capacity of soil)	II	Jenny and Overstreet जेनी और ओवरस्ट्रीट
C	Mobility of nutrients पोषक तत्वों की गतिशीलता (Mobility of nutrients)	III	Mitscherlich मिट्शरलिच (Mitscherlich)
D	Growth factor and yield वृद्धि कारक और उपज (Growth factor and yield)	IV	Kohnke कोनके (Kohnke)

(A)-(II), (B)-(IV), (C)-(I), (D)-(III) (A)-(II), (B)-(IV), (C)-(I), (D)-(III) (A)-(I), (B)-(II), (C)-(III), (D)-(IV) (A)-(I), (B)-(II), (C)-(III), (D)-(IV) (A)-(IV), (B)-(III), (C)-(II), (D)-(I) (A)-(IV), (B)-(III), (C)-(II), (D)-(I) (A)-(III), (B)-(IV), (C)-(I), (D)-(II) (A)-(III), (B)-(IV), (C)-(I), (D)-(II)

General Agriculture, Crop Production, Physiology & Rural Development

8 Topics

Agro-Climatic Zones, Cropping Systems, Tillage and Crop Establishment Historical Evolution, Agricultural Education and Research Infrastructure in India Water Management, Irrigation Scheduling, Evapotranspiration and Water Productivity Agricultural Meteorology, Weather Forecasting, Climate Change and Crop Modeling Plant Physiology: Photosynthesis (C3, C4, CAM), Respiration, Transpiration and Source-Sink Dynamics Agricultural Extension Systems, Rural Sociology and Developmental Programmes Plant Growth Regulators, Photoperiodism, Vernalization and Abiotic Stress Physiology Weed Biology, Weed Classification, Herbicides and Integrated Weed Management

Analytical, Physical & Organic Chemistry and Pesticides

9 Topics

Chemistry of Biomolecules: Carbohydrates, Lipids, Amino Acids, Proteins and Enzymes Volumetric and Gravimetric Analysis, Acid-Base Equilibria and Buffer Systems Synthetic Pesticides Chemistry: Organochlorines, Organophosphates, Carbamates and Synthetic Pyrethroids Organic Chemistry: Structure, Bonding, Stereochemistry, Functional Groups and Reaction Mechanisms Solutions, Colligative Properties, Colloids and Surface Chemistry Chemical Thermodynamics, Thermochemistry, Chemical Kinetics and Catalysis Electrochemistry, pH, Electrical Conductivity, Potentiometry and Redox Potentials Optical and Spectroscopic Analytical Methods: UV-Vis, AAS, Flame Photometry and ICP-OES Pesticide Formulations, Surfactants, Mode of Action, Residue Dynamics and Safety Regulations

Pedology, Soil Physics, Soil Colloids, Problem Soils & Water Quality

13 Topics

Earth Crust, Minerals, Rocks, Weathering Processes and Soil Formation Soil Water Retention, Energy Concepts, Soil Water Potential, Retention Curves (pF) and Hysteresis Soil Profile Morphology, Diagnostic Horizons, Pedogenic Regimes and Soil Survey Soil Colloids: Silicate Clay Minerals (1:1, 2:1 Expanding, Non-expanding), Sesquioxides and Amorphous Clays Soil Water Movement: Saturated, Unsaturated Flow, Darcys Law, Hydraulic Conductivity and Infiltration Soil Structure, Aggregation, Consistency, Crusting and Soil Crust Dynamics Soil Aeration, Gaseous Exchange, Diffusion, Soil Temperature, Heat Transfer and Thermal Regimes Soil Texture, Particle Size Distribution, Mechanical Analysis and Stokes Law Acid Soils: Genesis, Acidity Forms, Exchangeable Aluminum, Buffering and Liming Requirements Salt-Affected Soils: Saline, Sodic, Saline-Sodic Soils Genesis, Diagnostics and Gypsum Requirement Soil Bulk Density, Particle Density, Porosity, Compaction and Pore Size Distribution Ion Exchange Phenomena: Cation Exchange Capacity (CEC), Anion Exchange Capacity (AEC) and Base Saturation Active Irrigation Water Quality Standards: EC, SAR, RSC, Boron Hazard and Water Usability Classification

Soil Fertility, Classification, Remote Sensing, Soil Biology, Fertilizers & Pollution

13 Topics

Essential Plant Nutrients: Classification, Physiological Roles, Deficiency Symptoms and Mobility Remote Sensing, GIS, GPS, Digital Soil Mapping and Precision Agriculture Soil, Water and Atmospheric Pollution: Heavy Metal Toxicity, Radioactive Fallout, Agrochemical Contamination and Remediation Comprehensive Soil Taxonomy: 12 Soil Orders, Diagnostic Horizons, Nomenclature and Land Capability Classification Soil Nitrogen Dynamics: Mineralization, Nitrification, Denitrification, Ammonia Volatilization and BNF Soil Microbiology, Organic Matter Decomposition, Humus Chemistry, Humic Acids and Soil Enzymes Soil Erosion (Water and Wind), Universal Soil Loss Equation (USLE) and Soil Conservation Practices Soil Fertility Evaluation: Soil Testing Methods, Critical Levels, Plant Analysis, DRIS and Fertilizer Recommendations Chemical Fertilizers: Manufacture, Composition, Chemistry and Transformations of N, P, K Fertilizers Slow-Release Fertilizers, Nitrification Inhibitors, Biofertilizers and Integrated Nutrient Management (INM) Soil Potassium and Micronutrient Dynamics (Fe, Mn, Zn, Cu, B, Mo): Forms, Availability and Interactions Soil Phosphorus Dynamics: P Fixation, Retention, Adsorption Isotherms, Labile P and Release Mechanisms of Nutrient Uptake, Ion Translocation, Root Interception, Mass Flow and Diffusion

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ICAR AIEEA PG CUET UG Rajasthan Agriculture Pre-PG ICAR JRF/SRF

Physical Science Subjects

General Agriculture, Crop Production, Physiology & Rural Development

Analytical, Physical & Organic Chemistry and Pesticides

Pedology, Soil Physics, Soil Colloids, Problem Soils & Water Quality

Soil Fertility, Classification, Remote Sensing, Soil Biology, Fertilizers & Pollution

Previous Year Papers of Physical Science

ICAR AIEEA PG 2024 - Physical Science

ICAR AIEEA PG Physical Science 14 July 2023 Shift-1 Paper

ICAR AIEEA PG Physical Science 09 July 2023 (Shift 1) Paper

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RPSC Agriculture Exams

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Ion Exchange Phenomena: Cation Exchange Capacity (CEC), Anion Exchange Capacity (AEC) and Base Saturation - Physical Science | Agrigyan

Physical Science Subjects

General Agriculture, Crop Production, Physiology & Rural Development

Analytical, Physical & Organic Chemistry and Pesticides

Pedology, Soil Physics, Soil Colloids, Problem Soils & Water Quality

Soil Fertility, Classification, Remote Sensing, Soil Biology, Fertilizers & Pollution

Previous Year Papers of Physical Science

ICAR AIEEA PG 2024 - Physical Science

ICAR AIEEA PG Physical Science 14 July 2023 Shift-1 Paper

ICAR AIEEA PG Physical Science 09 July 2023 (Shift 1) Paper

Choose Exam

RPSC Agriculture Exams

RSSB Agriculture Exams

National & PG Entrances