1. In mineral soils under aerobic conditions, decomposition of organic matter generally _______

 Neutralizes soil pH

 Decreases soil pH

 Stabilizes soil pH completely

 Increases soil pH

2. Lightning contributes to soil acidification by forming _______

 Methane

 Ammonia

 Carbonates

 Nitric acid

3. Soil pH controls nutrient availability primarily through _______

 Mechanical action

 Soil aeration

 Physical adsorption

 Chemical equilibria

4. Among the following plant nutrients, availability of ____________ is least directly affected by soil pH

 Phosphorus (P)

 Iron (Fe)

 Potassium (K)

 Zinc (Zn)

5. High soil sodicity leads to _______

 Increased soil permeability

 Soil dispersion and poor structure

 Enhanced water infiltration

 Improved soil aggregation

6. At soil pH 8 (25 °C), the hydroxide ion concentration [OH⁻] relative to [H⁺] is _______

 Higher than [H⁺]

 Lower than [H⁺]

 Zero

 Equal to [H⁺]

7. In most mineral soils, phosphorus (P) availability to plants is lowest at _______

 Neutral pH

 Extremely acidic and alkaline conditions

 Moderately acidic pH

 Slightly alkaline pH

8. In organic soils, which component contributes most to pH buffering capacity?

 Humus

 Sand

 Gravel

 Clay

9. In alkaline soils, zinc (Zn) deficiency in plants is primarily due to _______

 Volatilization losses

 Leaching of Zn below the root zone

 Reduced solubility of Zn

 Oxidation of Zn species

10. In soil chemistry, most reactions (e.g., ion exchange, sorption, dissolution) are generally _______

 Reversible and establish dynamic equilibrium

 Static

 One-way

 Irreversible

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Soil Chemical Properties MCQs

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