Soil Chemical Properties MCQs Quiz 4

1. At pH 8, the concentration of OH⁻ compared to H⁺ is _______

 Equal

 Zero

 Higher

 Lower

2. Water dissociation in soil is represented by _______

 H₂O → H⁺ + O₂

 H₂O + CO₂ → H₂CO₃

 H₂O → H₂ + O₂

 H₂O ⇌ H⁺ + OH⁻

3. Limestone-derived soils are typically _______

 Saline

 Neutral

 Alkaline

 Acidic

4. The relationship between cation exchange capacity (CEC) and soil pH is best described as _______

 Random

 Independent

 Direct

 Inverse

5. In alkaline soils, the dominant reactive ion in the soil solution is _______

 Fe²⁺

 H⁺

 Al³⁺

 OH⁻

6. Which component primarily controls soil pH buffering in arid soils?

 Clay minerals

 Organic acids

 Oxides

 Carbonates

7. Cation exchange reactions in soils occur primarily on _______

 Soil air

 Sand particles

 Colloidal surfaces

 Water molecules

8. Which type of charge dominates in 2:1 clay minerals contributing to CEC?

 Permanent (structural) negative charge

 Positive charge

 Variable positive charge

 pH-dependent charge

9. An increase in soil organic matter will generally ________________________

 Decrease Cation Exchange Capacity

 Decrease nutrient retention

 Increase Cation Exchange Capacity

 Have no effect on Cation Exchange Capacity

10. Soil solution pH is primarily controlled by _______

 Soil texture alone

 Water content only

 H⁺ activity in soil solution

 Total nutrient content

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