Soil Science WEB Exam 11 Fall 2007 Dept. of Soil, Water and Climate
Directions 1. There is ONE BEST answer per question. 2.Place your answers on answer sheet, you only need to turn in the answers.
Name _____________________
1.________ 2._______ 3._________ 4._______ 5.______ 6._______ 7._________ 8._______
9.______ 10._______
Total=_/10 _______
__________Clay Minerals________________________
1. Cation Exchange Capacity requires the formation of negative charges and thus this equation is an example of __?__
a) isomorphous substitution in 2:1 clays.
b) isomorphous substitution in 1:1 clays.
c) disassociation of the carboxyl group in soil humus.
d) formation of a negative charge at the edge of a clay mineral.
2. All clay minerals start with the basic building blocks of __ ?.
a) phyllosilicates
b) silicon tetrahedral and aluminum octahedral
c) aluminum tetrahedral and silicon octahedral
d) aluminosilicates
3. Kaolinite's structure is composed of silicate sheets bonded to _________________ layers. The layers are tightly bonded together with only weak bonding existing between these paired layers.
a) aluminum oxide/hydroxide layers (Al2(OH)4) called gibsite
b) magnesium silicate layers (Mg3Si2O5(OH)4) called trigonal
c) magnesium/iron/silicate hydroxide layers (Mg,Fe)3Si2O5(OH)4 called orthorhombic.
4. One of the main uses of kaolinite is in __?___
a) lubricants
b) ceramics
c) kitty liter
d) pond or landfill liners
5. A 2:1 clay mineral will have __?___ compared to a 1:1 clay mineral.
a) no expanding space between layers.
b) lower amount of negative charges.
c) a missing hydrated interlayer
d) isomorphous substitution of Mg for Al or Al for Si
6. Vermiculite is similar to Illite except Vermiculite __?__
a) has a higher CEC
b) is not expansive due to the K bridge between layers
c) both a and b
7. Horticultural grade vermiculite is made by ___?___
a) processing raw vermiculite by adding water to swell the layers
b) grinding the vermiculite into a powder, adding steam and drying.
c) heating vermiculite (1000 degrees C) to change the interlayer water into steam
8. Isomorphous substitution is ___
a) the replacement of one atom by another of similar size (but different charge) in a crystal lattice without disrupting or changing the crystal structure of the mineral.
b) the movement of an element from the hydrated innerspace of the 2:1 clay mineral
c) the same for both 2:1 clay minerals and 1:1 clay minerals.
9. For soils that are maximally developed and the parent material is also very weathered, the most likely dominant kind of clay mineral in the soil would be____
a) 1:1
b) 2:1
c) both 2:1 and 1:1 would be of equal amount.
10. Which clay mineral is depicted in the figure?
a) Kaolinite
b) Illite
c) Smectite