The macronutrients which is an essential component of all organic compounds, yet not obtained by plants from soil is

Options

A. nitrogen
B. carbon
C. phosphorus
D. magnesium

Answer

To solve the question regarding which macronutrient is an essential component of all organic compounds but is not obtained by plants from the soil, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Macronutrients**:
- Macronutrients are nutrients that are required by plants in large amounts. They include elements like nitrogen, carbon, phosphorus, and magnesium.

2. **Evaluate Each Option**:
- **Option 1: Nitrogen**:
- Nitrogen is a macronutrient that plants obtain from the soil in the form of compounds such as ammonia, nitrate, and nitrite. Therefore, this option is incorrect.

- **Option 2: Carbon**:
- Carbon is also a macronutrient and is essential for all organic compounds. However, it is primarily obtained from the atmosphere in the form of carbon dioxide (CO2) and not from the soil. This makes carbon the correct answer.

- **Option 3: Phosphorus**:
- Phosphorus is another macronutrient that is obtained by plants from the soil, primarily from rock minerals. Thus, this option is incorrect.

- **Option 4: Magnesium**:
- Magnesium is also a macronutrient that is absorbed by plants from the soil. Therefore, this option is also incorrect.

3. **Conclusion**:
- After evaluating all the options, the only macronutrient that is essential for organic compounds and not obtained from the soil is **Carbon**.

### Final Answer:
The macronutrient which is an essential component of all organic compounds, yet not obtained by plants from soil is **Carbon** (Option 2).

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