Which of the following substances are used as fertilisers ?

Options

A. Nitrolim
B. Urea
C. Superphosphate of lime
D. Phosphorite mineral

Answer

To determine which substances are used as fertilizers from the given options, we will analyze each substance based on their properties and uses in agriculture.

### Step-by-Step Solution:

1. **Understanding Fertilizers**:
- Fertilizers are chemical compounds applied to crops to improve their production by providing essential nutrients like nitrogen, phosphorus, and potassium.

2. **Identifying the Options**:
- We have several substances to evaluate: Nitrolim, Urea, Superphosphate of Lime, and Phosphorite Mineral.

3. **Evaluating Nitrolim**:
- Nitrolim is calcium cyanamide (CaCN2), which is a nitrogenous fertilizer. It is produced by reacting calcium carbide with nitrogen gas at high temperatures. When water is added to nitrolim, it produces ammonia and calcium carbonate, both of which are beneficial for plants.
- **Conclusion**: Nitrolim is used as a fertilizer.

4. **Evaluating Urea**:
- Urea (NH2CO(NH2)2) is a widely used nitrogenous fertilizer, containing about 46% nitrogen. It promotes green leafy growth in plants. When urea is dissolved in water, it releases ammonia, which is absorbed by plants.
- **Conclusion**: Urea is used as a fertilizer.

5. **Evaluating Superphosphate of Lime**:
- Superphosphate of lime is produced by reacting calcium phosphate (Ca3(PO4)2) with phosphoric acid (H3PO4). It serves as a major source of phosphorus for plants, enriching the soil and aiding plant growth.
- **Conclusion**: Superphosphate of lime is used as a fertilizer.

6. **Evaluating Phosphorite Mineral**:
- Phosphorite is a rock phosphate mineral that is not directly used as a fertilizer. While it contains phosphorus, it needs to be processed to be effective as a fertilizer.
- **Conclusion**: Phosphorite mineral is not used as a fertilizer.

### Final Answer:
The substances used as fertilizers from the options are:
- Nitrolim
- Urea
- Superphosphate of Lime