Question 1

A 2:1 type silicate clay has one octahedral sheet sandwiched between two tetrahedral sheets.

Accepted Answer

A) True 
 B)False

Question 2

The cation exchange capacity of a soil is determined primarily by the amount and kind of colloids in the soil and by the pH.

Accepted Answer

A) True 
 B)False

Question 3

A well drained soil under a rain forest in Brazil contains significant amounts of a silicate clay.Which of the following is it most apt to be?

Accepted Answer

A) chlorite 
B) fine-grained mica 
C) smectite 
D) kaolinite 
E) vermiculite 
A) chlorite 
B) fine-grained mica 
C) smectite 
D) kaolinite 
E) vermiculite

Question 4

In most soils of the arid regions of Nevada, smectite is more prominent than in most soils in warm, humid Georgia.

Accepted Answer

A) True 
 B)False

Question 5

A tetrahedral sheet is characterized by a plane of aluminum atoms surrounded by oxygen and hydroxyl groups.

Accepted Answer

A) True 
 B)False

Question 6

Isomorphous substitution involves the substitution of a tetrahedral sheet for an octahedral sheet.

Accepted Answer

A) True 
 B)False

Question 7

Vermiculite and associated silicate clays have a net electropositive charge in slightly acid soils.

Accepted Answer

A) True 
 B)False

Question 8

Which cation would you expect to be mostly tightly held in a soil at pH 4.5?

Accepted Answer

A) K+ 
B) Ca2+ 
C) Al3+ 
D) Mg2+ 
E) Na+ 
A) K+ 
B) Ca2+ 
C) Al3+ 
D) Mg2+ 
E) Na+

Question 9

While kaolinite particles are larger than those of other major silicate clays, the surface area of kaolinite per kilogram is much smaller than that of the 2:1 type minerals.

Accepted Answer

A) True 
 B)False

Question 10

Iron and aluminum hydrous oxides are characteristic of soils that are highly weathered chemically.

Accepted Answer

A) True 
 B)False

Question 11

As biotite weathers in soils, which of the following would not likely develop by mere alteration of this mineral?

Accepted Answer

A) fine-grained mica 
B) kaolinite 
C) smectite 
D) chlorite 
E) vermiculite 
A) fine-grained mica 
B) kaolinite 
C) smectite 
D) chlorite 
E) vermiculite

Question 12

Anion exchange by formation of outer sphere complexes is of least importance in the plant absorption of _____.

Accepted Answer

A) NO3- 
B) Cl- 
C) SO42- 
D) MoO4-2 
E) H2PO4-. 
A) NO3- 
B) Cl- 
C) SO42- 
D) MoO4-2 
E) H2PO4-.

Question 13

Even at pH values near 7.0 some colloids such as iron and aluminum oxides have negative surface charges less than 10 cmolc/kg.

Accepted Answer

A) True 
 B)False

Question 14

If you were seeking a soil colloid with a high capacity to adsorb cationic pollutants, but also with a consistent capacity to do so even as the pH varied form 4.0 to 7.5, which of the following would you choose?

Accepted Answer

A) montmorillonite 
B) kaolinite 
C) fine-grained mica 
D) humus 
E) chlorite 
A) montmorillonite 
B) kaolinite 
C) fine-grained mica 
D) humus 
E) chlorite

Question 15

The order of strength of adsorption of ions by most colloids when they are present in equivalent quantities is Al>Ca>K>Mg>Na.

Accepted Answer

A) True 
 B)False

Question 16

If you were looking for a soil with high cation exchange capacity and were not concerned with the soil's physical properties, which of the following would most likely fit your needs?

Accepted Answer

A) Aridisol 
B) Oxisol 
C) Vertisol 
D) Mollisol 
E) Ultisol 
A) Aridisol 
B) Oxisol 
C) Vertisol 
D) Mollisol 
E) Ultisol

Question 17

The high cation adsorption capacity of vermiculite is due primarily to the substitution of silicon atoms for aluminum in the tetrahedral sheet.

Accepted Answer

A) True 
 B)False

Question 18

Kaolinite is most prevalent in soils developed from volcanic ejecta (Andisols).

Accepted Answer

A) True 
 B)False

Question 19

Some soil colloids exhibit positive charges under highly acid conditions.To what are these charges likely due?

Accepted Answer

A) protonation of some hydroxy groups by excess H+ ions 
B) the adsorption of Al3+ ions on the colloid 
C) the release of some OH- ions leaving an unsatisfied positive charge on the colloid 
D) substitution of lower valent atoms for higher valent atoms in the octahedral sheet 
E) increase in the level of H+ ions on the exchange complex 
A) protonation of some hydroxy groups by excess H+ ions 
B) the adsorption of Al3+ ions on the colloid 
C) the release of some OH- ions leaving an unsatisfied positive charge on the colloid 
D) substitution of lower valent atoms for higher valent atoms in the octahedral sheet 
E) increase in the level of H+ ions on the exchange complex

Question 20

Which of the following is not a characteristic of soil colloids?

Accepted Answer

A) very small size 
B) high external surfaces 
C) electronegative charges 
D) ability to exchange ions with the soil solution 
E) low water holding capacity 
A) very small size 
B) high external surfaces 
C) electronegative charges 
D) ability to exchange ions with the soil solution 
E) low water holding capacity

A 2:1 type silicate clay has one octahedral sheet sandwiched between two tetrahedral sheets.

The cation exchange capacity of a soil is determined primarily by the amount and kind of colloids in the soil and by the pH.

A well drained soil under a rain forest in Brazil contains significant amounts of a silicate clay.Which of the following is it most apt to be?

In most soils of the arid regions of Nevada, smectite is more prominent than in most soils in warm, humid Georgia.

A tetrahedral sheet is characterized by a plane of aluminum atoms surrounded by oxygen and hydroxyl groups.

Isomorphous substitution involves the substitution of a tetrahedral sheet for an octahedral sheet.

Vermiculite and associated silicate clays have a net electropositive charge in slightly acid soils.

Which cation would you expect to be mostly tightly held in a soil at pH 4.5?

While kaolinite particles are larger than those of other major silicate clays, the surface area of kaolinite per kilogram is much smaller than that of the 2:1 type minerals.

Iron and aluminum hydrous oxides are characteristic of soils that are highly weathered chemically.

As biotite weathers in soils, which of the following would not likely develop by mere alteration of this mineral?

Anion exchange by formation of outer sphere complexes is of least importance in the plant absorption of _____.

Even at pH values near 7.0 some colloids such as iron and aluminum oxides have negative surface charges less than 10 cmol_c/kg.

If you were seeking a soil colloid with a high capacity to adsorb cationic pollutants, but also with a consistent capacity to do so even as the pH varied form 4.0 to 7.5, which of the following would you choose?

The order of strength of adsorption of ions by most colloids when they are present in equivalent quantities is Al>Ca>K>Mg>Na.

If you were looking for a soil with high cation exchange capacity and were not concerned with the soil's physical properties, which of the following would most likely fit your needs?

The high cation adsorption capacity of vermiculite is due primarily to the substitution of silicon atoms for aluminum in the tetrahedral sheet.

Kaolinite is most prevalent in soils developed from volcanic ejecta (Andisols).

Some soil colloids exhibit positive charges under highly acid conditions.To what are these charges likely due?

Which of the following is not a characteristic of soil colloids?

The Soils Around US

Formation of Soils From Parent Materials

Soil Classification

Soil Architecture and Physical Properties

Soil Water: Characteristics and Behavior

Soil and the Hydrologic Cycle

Soil Aeration and Temperature

Soil Acidity

Soils of Dry Regions: Alkalinity, Salinity, and Sodicity

Organisms and Ecology of the Soil

Soil Organic Matter

Nitrogen and Sulfur Economy of Soils

Soil Phosphorus and Potassium

Micronutrients and Other Trace Elements

Practical Nutrient Management

Soil Erosion and Its Control

Soils and Chemical Pollution

Geographic Soils Information

Prospects for Global Soil Quality

Filters

Exam 8: Soil Colloids: Seat of Soil Chemical and Physical Activity

A 2:1 type silicate clay has one octahedral sheet sandwiched between two tetrahedral sheets.

The cation exchange capacity of a soil is determined primarily by the amount and kind of colloids in the soil and by the pH.

A well drained soil under a rain forest in Brazil contains significant amounts of a silicate clay.Which of the following is it most apt to be?

In most soils of the arid regions of Nevada, smectite is more prominent than in most soils in warm, humid Georgia.

A tetrahedral sheet is characterized by a plane of aluminum atoms surrounded by oxygen and hydroxyl groups.

Isomorphous substitution involves the substitution of a tetrahedral sheet for an octahedral sheet.

Vermiculite and associated silicate clays have a net electropositive charge in slightly acid soils.

Which cation would you expect to be mostly tightly held in a soil at pH 4.5?

While kaolinite particles are larger than those of other major silicate clays, the surface area of kaolinite per kilogram is much smaller than that of the 2:1 type minerals.

Iron and aluminum hydrous oxides are characteristic of soils that are highly weathered chemically.

As biotite weathers in soils, which of the following would not likely develop by mere alteration of this mineral?

Anion exchange by formation of outer sphere complexes is of least importance in the plant absorption of _____.

Even at pH values near 7.0 some colloids such as iron and aluminum oxides have negative surface charges less than 10 cmolc/kg.

If you were seeking a soil colloid with a high capacity to adsorb cationic pollutants, but also with a consistent capacity to do so even as the pH varied form 4.0 to 7.5, which of the following would you choose?

The order of strength of adsorption of ions by most colloids when they are present in equivalent quantities is Al>Ca>K>Mg>Na.

If you were looking for a soil with high cation exchange capacity and were not concerned with the soil's physical properties, which of the following would most likely fit your needs?

The high cation adsorption capacity of vermiculite is due primarily to the substitution of silicon atoms for aluminum in the tetrahedral sheet.

Kaolinite is most prevalent in soils developed from volcanic ejecta (Andisols).

Some soil colloids exhibit positive charges under highly acid conditions.To what are these charges likely due?

Which of the following is not a characteristic of soil colloids?

The Soils Around US

Formation of Soils From Parent Materials

Soil Classification

Soil Architecture and Physical Properties

Soil Water: Characteristics and Behavior

Soil and the Hydrologic Cycle

Soil Aeration and Temperature

Soil Acidity

Soils of Dry Regions: Alkalinity, Salinity, and Sodicity

Organisms and Ecology of the Soil

Soil Organic Matter

Nitrogen and Sulfur Economy of Soils

Soil Phosphorus and Potassium

Micronutrients and Other Trace Elements

Practical Nutrient Management

Soil Erosion and Its Control

Soils and Chemical Pollution

Geographic Soils Information

Prospects for Global Soil Quality

Filters

Even at pH values near 7.0 some colloids such as iron and aluminum oxides have negative surface charges less than 10 cmol_c/kg.