Specific surface area ($S_w$) is inversely proportional to particle diameter ($S_w = \frac{6}{\rho \cdot d}$).
Coarse sand grains ($0.05 - 2.0\text{ mm}$) have very small surface areas per unit mass, typically $\lt 2\text{ m}^2/\text{g}$ (often $0.01 - 0.1\text{ m}^2/\text{g}$), compared to $10 - 40\text{ m}^2/\text{g}$ for illite and up to $800\text{ m}^2/\text{g}$ for smectite clay. (Correct answer: Option 2)
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Formulated by Stephen Brunauer, Paul Hugh Emmett, and Edward Teller.
Extends Langmuir's monolayer adsorption model to describe multilayer physical gas adsorption on porous solid surfaces, serving as the international standard method for measuring specific surface area of soil clays. (Correct answer: Option 2)
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Kaolinite is a 1:1 non-expanding aluminosilicate clay mineral characterized by a low silica-to-alumina ratio ($SiO_2 : Al_2O_3 = 2 : 1$).
Forms under advanced, intense weathering where high temperatures and heavy leaching remove basic cations and silica—conditions characteristic of warm, humid tropical and equatorial regions (Oxisols and Ultisols). (Correct answer: Option 1)
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Q.35
Agricultural Meteorology- ICAR JRF/SRF 2024
MCQ (Single Correct)
Water risen in a capillary tube is characterized by a
Capillary rise of water in soil pores or glass tubes occurs against gravity due to surface tension and adhesive forces.
Water held in the capillary meniscus above a free water table is under hydrostatic suction/tension, existing at sub-atmospheric pressure characterized by a negative pressure potential (matric potential, $\psi_p \lt 0$). (Correct answer: Option 2)
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