Soil Chemistry Quiz - Soil Properties and pH

Question 1

• Swelling/shrinking of silicate clay minerals primarily due to the movement of soil solution in and out of the crystal interlayers, and expansion/contraction in the interlayers due to ions like K+
• Cations are attracted to negative charges on internal surfaces

Question 2

• A soil with pH 7 has a H+ concentration of 0.0000001

Question 3

• For a very stable foundation with low adsorption capacity, choose kaolinite

Question 4

• pH-dependent charge decreases as soil pH decreases

Question 5

• 50 g of Ca2+ (molar mass = 40 g/mol) contains 1.7 moles of positive charge

Question 6

• One mole of Mg2+ contains 6.02 x 10^23 Mg2+ ions

Question 7

• Similar CEC values at different pH levels likely due to a lack of significant charge differences across the pH range

Question 8

• Illite clay provides the best fertility for soils

Question 9

• Information unavailable to answer the question

Question 10

• Poorly buffered soils require more lime than well-buffered soils to adjust pH

Question 11

• Electronegative charge on 2:1 type silicate clays primarily due to isomorphic substitution of one metallic atom for another in the crystal structure of the clay.

Question 12

• Negative charges associated with smectite clay crystals mainly due to isomorphic substitution

Question 13

• Information in table required to calculate Base Saturation of the soil (values for various cations are given)

Question 14

• Alkaline soil with 10% clay and 1.5% humus has a CEC of 11 cmolc/kg

Question 15

• Building a foundation on smectite-rich soil is not always a good idea

Question 16

• Soil colloids characterized by very small size

Question 17

• Positive charges on soil colloids under highly acidic conditions are likely due to protonation of some hydroxy groups by excess H+ ions.

Question 18

• One mole of Al3+ contains 3 moles of positive charge

Question 19

• pH of soil with H+ concentration of 0.000000063 is 6.5

Question 20

• Residual acidity in clay loam soil requires considerably less lime than active acidity in the same soil.

Question 21

• Phosphorus is generally most available to plants in a soil pH range of 4.5 - 5.5

Question 22

• Information missing to determine the answer

Question 23

• CEC of soil is 20.5

Question 24

• Acid rain's impact on well-buffered soils is likely to be minimal

Question 25

• Spatial variation is checking soil pH at multiple spots in a field to account for variations in field conditions

Question 26

• Secondary minerals are most prominent in the silt fraction of soils

Question 27

• Soil colloid with a high cation exchange capacity (CEC) and tendency to swell when wetted is most likely of monmorillinite

Question 28

• Humus is similar to 2:1 type minerals in its ability to adsorb cations

Question 29

• Cation exchange capacity of vermiculite increases as pH increases is False

Question 30

• Soil with a high CEC is likely to be highly buffered

Question 31

• External surfaces of 2:1 type clays are typically much more extensive than their internal surfaces

Question 32

• Information unavailable to answer the question

Question 33

• A octahedral sheet is characterized by a plane of aluminum atoms surrounded by oxygen and hydroxyl groups

Question 34

• Information unavailable to answer the question

Question 35

• Farmers can significantly decrease soil pH by using NH4+-based fertilizers

Question 36

• Information missing to determine the answer

Question 37

• For a liming material with a CaCO3 equivalent of 0.90, 7,407 lbs of material are needed to achieve the same liming effect as 1.5 tons of 100% CaCo3.

Question 38

• Soils developed in marine marshes become extremely acidic when drained due to oxidation of sulphides

Question 39

• Elemental sulfur is the most appropriate for decreasing soil pH to grow azaleas

Question 40

• A soil with 30% clay would have the greatest potassium-fixing capacity due to 2:1 clays

Question 41

• Information unavailable to answer the question

Question 42

• Finely ground dolomitic limestone is favored when needing to significantly reduce exchangeable Al3+ in the soil

Question 43

• The Calcium Carbonate Equivalent of MgCO3 is 0.93.

Question 44

• Soil pH can vary with soil depth is True

Question 45

• A soil with a CEC of 40 cmolc/kg would likely be highly buffered

Question 46

• 100 kg of 95% pure CaO is approximately 97.5% as effective as 100 kg of 100% pure CaCO3

Question 47

• Effectiveness of lime based only on size is 0.44 lbs reactive material/lb total lime

Question 48

• Information unavailable to answer the question

Question 49

• Applying 4 tons of lime to a sandy soil would likely lead to a higher pH than intended

Question 50

• The Calcium Carbonate Equivalent of CaMg(CO3)2 is 0.54