AGN 215 Soils Test 2 questions with
verified answers graded A+
Define the term "soil colloids". - correct answer ✔✔- organic and inorganic matter with very
small particle size and a corresponding large surface area per unit mass
Colloid fraction - correct answer ✔✔clay and humus particles
soil colloids - correct answer ✔✔extermely small mineral or organic particles that can remain
suspended in water indefinitely
Cation - correct answer ✔✔Positive charge ion
Anion - correct answer ✔✔Negative charged ion
Cations - correct answer ✔✔Al3+ Aluminum
H+ Hydrogen
Ca2+ Calcium
Mg2+ Magnesium
K+ Potassium
Na+ sodium
Adsorbed - loosely held
Al3+> Ca2+> Mg2+ > Na+> H+
, Why are soil colloids referred to as the active fraction of soils? - correct answer ✔✔Exchange of
nutrients take place
Why is Ch 8 calling them the "Seat of Soil Chemistry"? - correct answer ✔✔they are the
foundation of chemical properties and reactions as a result of clay and humus in the soil
What is the difference between a tetrahedron and octahedron? - correct answer
✔✔Tetrahedron- Si surrounded by 4O; 4 sided with a pore (Si)
Octahedron- Al(or others) surrounded by 6O; 8 sided with a pore (Al)
Adsorption - correct answer ✔✔accumulation of a substance or material at an interface
between the solid surface and the bathing solution
How are they arranged into sheets? - correct answer ✔✔Tetra- 2 planes of oxygens with mainly
silicon in the spaces between the oxygens
Octa- 2 planes of oxygens with mainly Al in the spaces between the oxygens
What is the difference between a 1:1 clay structure and a 2:1 clay structure? - correct answer
✔✔1:1 clay - 1 layer of tetrahedrons, 1 layer of octahedrons tetra, octa, space
2:1 clay - 2 layers of tetrahedrons, 1 layer octahedrons
tetra, octa, tetra, space
Differences in the 5 silicate clays: 1:1 - correct answer ✔✔tetra octa
Differences in the 5 silicate clays: 2:1 - correct answer ✔✔tetra octa tetra
Differences in the 5 silicate clays: 2:2 - correct answer ✔✔tetra octa tetra hydroxide
verified answers graded A+
Define the term "soil colloids". - correct answer ✔✔- organic and inorganic matter with very
small particle size and a corresponding large surface area per unit mass
Colloid fraction - correct answer ✔✔clay and humus particles
soil colloids - correct answer ✔✔extermely small mineral or organic particles that can remain
suspended in water indefinitely
Cation - correct answer ✔✔Positive charge ion
Anion - correct answer ✔✔Negative charged ion
Cations - correct answer ✔✔Al3+ Aluminum
H+ Hydrogen
Ca2+ Calcium
Mg2+ Magnesium
K+ Potassium
Na+ sodium
Adsorbed - loosely held
Al3+> Ca2+> Mg2+ > Na+> H+
, Why are soil colloids referred to as the active fraction of soils? - correct answer ✔✔Exchange of
nutrients take place
Why is Ch 8 calling them the "Seat of Soil Chemistry"? - correct answer ✔✔they are the
foundation of chemical properties and reactions as a result of clay and humus in the soil
What is the difference between a tetrahedron and octahedron? - correct answer
✔✔Tetrahedron- Si surrounded by 4O; 4 sided with a pore (Si)
Octahedron- Al(or others) surrounded by 6O; 8 sided with a pore (Al)
Adsorption - correct answer ✔✔accumulation of a substance or material at an interface
between the solid surface and the bathing solution
How are they arranged into sheets? - correct answer ✔✔Tetra- 2 planes of oxygens with mainly
silicon in the spaces between the oxygens
Octa- 2 planes of oxygens with mainly Al in the spaces between the oxygens
What is the difference between a 1:1 clay structure and a 2:1 clay structure? - correct answer
✔✔1:1 clay - 1 layer of tetrahedrons, 1 layer of octahedrons tetra, octa, space
2:1 clay - 2 layers of tetrahedrons, 1 layer octahedrons
tetra, octa, tetra, space
Differences in the 5 silicate clays: 1:1 - correct answer ✔✔tetra octa
Differences in the 5 silicate clays: 2:1 - correct answer ✔✔tetra octa tetra
Differences in the 5 silicate clays: 2:2 - correct answer ✔✔tetra octa tetra hydroxide
