Soil Science - Study Mode
[#916] Term 'Bioavailable' was coined by
Correct Answer
(D) Barber
Explanation
Solution: Bioavailability is the term that refers to the subcategory of absorption and is the fraction of an administered drug that reaches the systemic circulation. It is used to describe the percentage of an administered dose of a xenobiotic that reaches the systemic circulation. The term ‘Bioavailable’ was coined by Barber . It is denoted by the letter f.
[#917] A clay soil must contain at least . . . . . . . . Clay separate, to be designated a clay
Correct Answer
(D) 35%
Explanation
Solution: Clay soil must contain at least 35% clay separate, to be designated clay. Clay soil is comprised of very fine mineral particles and not much organic material, which makes it quite sticky and it does not drain well at all. Clay develops plasticity when wet, due to a molecular film of water surrounding the clay particles, but becomes hard, brittle and non-plastic upon drying or firing.
[#918] The major nutrients are
Correct Answer
(B) N, P, K
Explanation
Solution: Out of the 17 essential nutrients, a few of them are major nutrients and these are N (Nitrogen), P (Phosphorus) and K (Potassium). These are also termed as “Big 3” primary nutrients in commercial fertilizers. Plants need significant amounts of nitrogen, phosphorus and potassium to grow and develop. These help in vegetative growth in stems and roots particularly during the early stages, root growth, seed and flower formation, bud growth and ripening of fruits.
[#919] Plasticity of soil can be determined by using
Correct Answer
(C) Atterberg's apparatus
Explanation
Solution: Plasticity of the soil is the ability of a material to undergo permanent deformation under stress without cracking. Fine-grained soils become plastic as their moisture content is increased, leading to a loss in shear strength and stability. The plasticity of soil can be determined by using Atterberg’s Apparatus . it helps in determining with a series of laboratory tests that classify the properties of silt and clay soils at different moisture contents.
[#920] Consider the following statements. Cation exchange of soil colloidal clay is due to 1. Silicon tetrahedral layer 2. Isomorphous substitution 3. Hydration of clays 4. Broken edges of clay lattices The correct sequence is
Correct Answer
(B) 2 and 4
Explanation
Solution: Cation exchange in the soil is the capacity of the particles to attract and absorb cations (positively charged ions). Cation exchange of soil colloidal clay is due to isomorphous substitution and broken edges of clay lattices. Isomorphous substitution in a clay mineral is the process of replacing one structural cation for another of similar size.