Heavy metals defined as elements with density are harmful to ecological systems

Options

A. ` gt 1 g // cm ^(3)`
B. ` gt 2g // cm ^(3)`
C. ` gt 4 g// cm ^(3)`
D. ` gt 5g // cm ^(3)`

Answer

**Step-by-Step Solution:**

1. **Understanding Heavy Metals**: Heavy metals are defined as elements that have a high density, which is typically greater than a certain threshold. In this context, we are looking for a specific density that categorizes these metals as harmful.

2. **Density Threshold**: The question provides several options for density thresholds: greater than 1 g/cm³, greater than 2 g/cm³, greater than 4 g/cm³, and greater than 5 g/cm³. We need to identify which of these thresholds is appropriate for classifying heavy metals.

3. **Identifying the Correct Density**:
- Heavy metals are generally considered to have a density greater than 5 g/cm³. This is a commonly accepted threshold in environmental science.
- Therefore, the correct option among the provided choices is "greater than 5 g/cm³".

4. **Sources of Heavy Metals**: Heavy metals are often released into the environment through industrial processes, such as:
- Petroleum industry
- Paper manufacturing
- Metal extraction and processing
- Chemical manufacturing

5. **Impact on Ecological Systems**: Unlike domestic sewage, which primarily contains biodegradable substances, industrial wastewater often contains toxic substances, including heavy metals. These heavy metals can accumulate in the environment and pose significant risks to ecological systems.

6. **Examples of Heavy Metals**: Common heavy metals that are harmful to the environment include:
- Mercury
- Cadmium
- Copper
- Lead

7. **Conclusion**: Heavy metals, defined as elements with a density greater than 5 g/cm³, are harmful to ecological systems due to their toxicity and persistence in the environment.

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