Most mineral cations are

Options

A. adsorbed on soil surface
B. leached from the soil solution by percolating water
C. exchanged with anions on the surface of clay particles
D. More than one option is correct

Answer

**Step-by-Step Solution:**

1. **Understanding Mineral Cations**: Mineral cations are positively charged ions that play crucial roles in plant nutrition and soil chemistry. They include elements like potassium (K+), calcium (Ca2+), magnesium (Mg2+), and others.

2. **Functions of Mineral Cations**:
- **pH Regulation**: Mineral cations help maintain the pH level of the soil, which is essential for nutrient availability and overall soil health.
- **Nutrient Absorption**: They facilitate the absorption of nutrients by plants. Cations are absorbed by plant roots from the soil solution.

3. **Location of Absorption**: Mineral cations are primarily absorbed from the soil surface. They are attracted to the negatively charged surfaces of soil particles and are found in the soil solution around the roots.

4. **Cation Exchange**: Cations can exchange with anions (negatively charged ions) on the surface of soil particles. This exchange is vital for nutrient uptake by plants.

5. **Evaluating Options**:
- **Option 1**: "Absorbed on soil surface" - This is correct as mineral cations are indeed absorbed from the soil surface.
- **Option 2**: "Leached from the soil solution and percolating water" - This is incorrect as mineral cations are not typically supplied externally; they are absorbed by the plant roots.
- **Option 3**: "Exchange with anions on the surface of clay particles" - While cations do exchange with anions, the primary focus is on their absorption from the soil surface.
- **Option 4**: "More than one option is correct" - This is incorrect as only one option is valid.

6. **Conclusion**: The correct answer is that mineral cations are absorbed on the soil surface.