Soil Chemical Properties MCQs Quiz 4

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

 Oxides

 Clay minerals

 Organic acids

 Carbonates

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

 Positive charge

 pH-dependent charge

 Variable positive charge

 Permanent (structural) negative charge

3. Water dissociation in soil is represented by _______

 H₂O → H₂ + O₂

 H₂O ⇌ H⁺ + OH⁻

 H₂O + CO₂ → H₂CO₃

 H₂O → H⁺ + O₂

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

 Zero

 Equal

 Lower

 Higher

5. Soil solution pH is primarily controlled by _______

 H⁺ activity in soil solution

 Water content only

 Total nutrient content

 Soil texture alone

6. Cation exchange reactions in soils occur primarily on _______

 Colloidal surfaces

 Sand particles

 Water molecules

 Soil air

7. An increase in soil organic matter will generally ________________________

 Have no effect on Cation Exchange Capacity

 Decrease Cation Exchange Capacity

 Decrease nutrient retention

 Increase Cation Exchange Capacity

8. Limestone-derived soils are typically _______

 Saline

 Neutral

 Alkaline

 Acidic

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

 H⁺

 Fe²⁺

 Al³⁺

 OH⁻

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

 Direct

 Inverse

 Random

 Independent

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