Which of the following is not an essential mineral element for plants?

Options

A. Potassium
B. Magnesium
C. Calcium
D. Lead

Answer

To determine which of the following is not an essential mineral element for plants, we need to analyze the given options: potassium, magnesium, calcium, and lead.

### Step-by-Step Solution:

1. **Identify Essential Mineral Elements**: Essential mineral elements for plants are categorized into two groups: macronutrients and micronutrients. Macronutrients are required in larger amounts, while micronutrients are needed in smaller quantities.

2. **List the Macronutrients**: Common macronutrients include:
- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
- Nitrogen (N)
- Phosphorus (P)
- Sulfur (S)
- Potassium (K)
- Calcium (Ca)
- Magnesium (Mg)

3. **List the Micronutrients**: Common micronutrients include:
- Iron (Fe)
- Manganese (Mn)
- Copper (Cu)
- Molybdenum (Mo)
- Zinc (Zn)
- Boron (B)
- Chlorine (Cl)
- Nickel (Ni)

4. **Analyze Each Option**:
- **Potassium (K)**: This is a macronutrient and essential for plant growth.
- **Magnesium (Mg)**: This is also a macronutrient and essential for plants.
- **Calcium (Ca)**: This is another macronutrient and essential for plant health.
- **Lead (Pb)**: This element is not required by plants and is actually toxic to them.

5. **Conclusion**: Since lead is not classified as either a macronutrient or a micronutrient and is harmful to plants, it is the correct answer to the question.

### Final Answer:
Lead is not an essential mineral element for plants.

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