Which one of the following is not a micronutrient?

Options

A. Boron
B. Molybdenum
C. Magnesium
D. Zinc

Answer

**Step-by-Step Solution:**

1. **Understand the Concept of Micronutrients and Macronutrients:**
- Micronutrients are essential elements that plants require in very small amounts (typically less than 100 mg per kg of dry matter). They play crucial roles in various physiological functions.
- Macronutrients, on the other hand, are required in larger quantities (more than 100 mg per kg of dry matter) and are vital for plant growth and development.

2. **Identify the Elements Listed in the Question:**
- The options provided are:
- Boron
- Molybdenum
- Magnesium
- Zinc

3. **Classify Each Element:**
- **Boron:** A micronutrient required in small amounts.
- **Molybdenum:** A micronutrient required in small amounts.
- **Magnesium:** A macronutrient required in larger amounts.
- **Zinc:** A micronutrient required in small amounts.

4. **Determine Which Element is Not a Micronutrient:**
- From the classification, it is clear that magnesium is the only element listed that is classified as a macronutrient, while boron, molybdenum, and zinc are all micronutrients.

5. **Conclude the Answer:**
- Therefore, the answer to the question "Which one of the following is not a micronutrient?" is **Magnesium**.

**Final Answer: Magnesium is not a micronutrient.**

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