Phosphates remain outside the natural cycle for a long time

Options

A. When they form compounds with metals
B. When they are incorporated in bones and teeth
C. When the bodies of the organisms excrete and decompose
D. Both (1) and (2)

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question states that phosphates remain outside the natural cycle for a long time. We need to identify the reasons why this occurs.

2. **Identifying Phosphate Sources**: Phosphates can be found in various forms, primarily in rocks, bones, teeth, and shells. They are part of the biogeochemical cycle, specifically the sedimentary cycle.

3. **Formation of Compounds**: Phosphates can form compounds with metals, particularly calcium. This occurs when phosphates are incorporated into biological structures such as bones and teeth.

4. **Decomposition Process**: When organisms die, their bodies decompose. During this decomposition, phosphates are released back into the environment, allowing them to re-enter the natural cycle.

5. **Analyzing the Options**:
- **Option 1**: Phosphates form compounds with metals.
- **Option 2**: Phosphates are incorporated into bones and teeth.
- **Option 3**: Bodies of organisms excrete and decompose.
- **Option 4**: Both options 1 and 2.

6. **Conclusion**: Since phosphates are primarily held in bones and teeth and can form complexes with metals, they remain outside the natural cycle until decomposition occurs. Therefore, both options 1 and 2 are correct, making option 4 the right answer.

### Final Answer:
The correct option is **4 (both 1 and 2)**.

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