Which of the following substance can be used directly as feritizer?

Options

A. `(NH_(4))_(2)SO_(4)`
B. `Ca_(3)(PO_(4))_(2)`
C. `Ca(H_(2)PO_(4))_(2)`
D. `CaCN_(2)+C`

Explanation

To determine which of the given substances can be used directly as a fertilizer, we will analyze each compound mentioned in the question.

### Step 1: Identify the compounds
The compounds mentioned are:
1. NH4O2SO4 (Ammonium sulfate)
2. Ca3(PO4)2 (Calcium phosphate)
3. Ca(H2PO4)2 (Calcium dihydrogen phosphate)
4. CaCN2 (Calcium cyanamide, also known as Nitrolim)

### Step 2: Analyze each compound for fertilizer use
1. **Ammonium sulfate (NH4O2SO4)**:
- This compound is widely used as a fertilizer. It provides nitrogen, which is essential for plant growth.

2. **Calcium phosphate (Ca3(PO4)2)**:
- This compound is also used in agriculture as a fertilizer. It supplies phosphorus, which is crucial for root development and flowering in plants.

3. **Calcium dihydrogen phosphate (Ca(H2PO4)2)**:
- This compound is a tertiary phosphate and is not soluble in water. Since it does not dissolve well, it is not readily available for plants to absorb, making it unsuitable for direct use as a fertilizer.

4. **Calcium cyanamide (CaCN2)**:
- This compound is used in the manufacturing of fertilizers. It can be converted into ammonium compounds in the soil, which are beneficial for plants.

### Step 3: Conclusion
From the analysis:
- **Ammonium sulfate (1)**, **Calcium phosphate (2)**, and **Calcium cyanamide (4)** can be used directly as fertilizers.
- **Calcium dihydrogen phosphate (3)** cannot be used directly as a fertilizer due to its low solubility.

Thus, the substances that can be used directly as fertilizers are:
1. Ammonium sulfate (NH4O2SO4)
2. Calcium phosphate (Ca3(PO4)2)
3. Calcium cyanamide (CaCN2)

### Final Answer:
The substances that can be used directly as fertilizers are:
- Ammonium sulfate (NH4O2SO4)
- Calcium phosphate (Ca3(PO4)2)
- Calcium cyanamide (CaCN2)