Select an incorrect statement

Options

A. Nitrogen is not considered a true mineral.
B. Nitrogen is inert and plants cannot make use of it directly.
C. Nitrogen is absorbed by plants in the form of nitrogen gas
D. Phosphorus is absorbed as phosphate, and sulphur mainly as sulphate.

Explanation

To solve the question of selecting an incorrect statement regarding mineral nutrition in plants, we will analyze each statement provided.

### Step-by-Step Solution

1. **Identify the Statements**:
- We need to analyze the four statements provided in the question to determine which one is incorrect.

2. **Evaluate the First Statement**:
- The first statement claims that "Nitrogen is not considered as a true mineral."
- This statement is **correct** because nitrogen is primarily found in the gaseous form (N2) in the atmosphere and is not a mineral that is typically found in soil.

3. **Evaluate the Second Statement**:
- The second statement suggests that "Nitrogen will be inert and plants will not be able to use it directly."
- This statement is also **correct**. Plants cannot directly utilize atmospheric nitrogen; it must first undergo nitrogen fixation and conversion into usable forms such as ammonia, nitrite, or nitrate.

4. **Evaluate the Third Statement**:
- The third statement states that "Plants absorb nitrogen in the form of ammonia, nitrite, and mainly nitrate."
- This statement is **correct** as plants do absorb nitrogen in these forms after it has been converted from atmospheric nitrogen.

5. **Evaluate the Fourth Statement**:
- The fourth statement claims that "Phosphorus is absorbed as phosphate and sulphur is mainly sulphate."
- This statement is **correct** because phosphorus is indeed absorbed by plants in the form of phosphate ions (PO4^3-) and sulfur in the form of sulfate ions (SO4^2-).

6. **Conclusion**:
- After evaluating all four statements, we find that all of them are correct. However, if we consider the context of the question, the statement about nitrogen being inert and not directly usable by plants is often misunderstood. Therefore, the statement that "plants absorb nitrogen in the form of nitrogen gas" is incorrect as plants cannot absorb nitrogen gas directly.

### Final Answer
The incorrect statement is: "Plants absorb nitrogen in the form of nitrogen gas."