Let's analyze each of your questions:
29. Which of the following is true at a low pH:
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a) Micronutrients such as Ca and Mg are insoluble and inaccessible to plants.
False — While the solubility of some forms of Ca and Mg may be reduced at low pH, they are generally not micronutrients; they are actually considered macronutrients. -
b) Micronutrients such as Fe, Mn, and Zn are soluble and accessible to plants.
True — At low pH, Fe, Mn, and Zn are often more soluble, making them more available for plant uptake. -
c) Macronutrients such as Fe, Mn, and Zn are insoluble and inaccessible to plants.
False — Fe, Mn, and Zn are actually considered micronutrients, not macronutrients. -
d) Macronutrients such as Ca and Mg are soluble and accessible to plants.
Somewhat true but misleading. Calcium and magnesium can be available at low pH, but their solubility can be affected negatively at very low pH. -
e) All of the above.
False — Since some statements are false. -
f) None of the above.
False — Since statement b is true.
The correct answer is: b) Micronutrients such as Fe, Mn, and Zn are soluble and accessible to plants.
30. A thick diffused double layer results in:
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a) Dispersed clay particles and an increased saturation hydraulic conductivity.
False — A thick diffuse double layer generally leads to dispersed particles. -
b) Flocculated clay particles and an increased saturated hydraulic conductivity.
False — A thick diffuse double layer typically leads to dispersion, not flocculation. -
c) Dispersed clay particles and a reduced saturated hydraulic conductivity.
True — Dispersed clay particles cannot pack closely together, reducing hydraulic conductivity. -
d) Flocculated clay particles and a reduced saturated hydraulic conductivity.
False — Flocculation typically would increase hydraulic conductivity. -
e) All of the above.
False — Not all statements are true. -
f) None of the above.
False — Since statement c is true.
The correct answer is: c) Dispersed clay particles and a reduced saturated hydraulic conductivity.
31. The thickness of the diffuse double layer depends on:
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a) The cation concentration and composition.
True — This affects the charge balance in the soil solution. -
b) The cation and anion concentration and composition.
True — Both cation and anion concentrations can influence the thickness of the double layer. -
c) The anion concentration and composition.
True — Anions also contribute to the electrochemical balance. -
d) All of the above.
True — Since a), b), and c) are all true. -
e) None of the above.
False — As all statements a, b, and c are true.
The correct answer is: d) All of the above.
Feel free to ask for further clarifications or questions!
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