A phenomenon by which an element occurs in different physical modification in same physical state is called

Options

A. isomerism
B. allotropy
C. amorphous
D. crystalline

Explanation

**Step-by-Step Solution:**

1. **Understanding the Concept**: The question asks about a phenomenon where an element can exist in different physical modifications while remaining in the same physical state. This concept is essential in chemistry as it helps explain the diversity of materials that can be formed from a single element.

2. **Defining the Term**: The phenomenon where an element can exist in different forms or modifications in the same physical state is known as "allotropy."

3. **Examples of Allotropy**: A common example of allotropy is carbon. Carbon can exist in different forms such as:
- **Diamond**: A solid form of carbon that is hard and has a crystal structure.
- **Graphite**: Another solid form of carbon that is soft and has a layered structure.
- **Fullerenes**: A form of carbon that consists of molecules composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube.

4. **Physical vs. Chemical Properties**: While these different forms of carbon (diamond, graphite, and fullerenes) have similar chemical properties (they are all forms of carbon), their physical properties differ significantly. For instance, diamond is transparent and hard, while graphite is opaque and slippery.

5. **Conclusion**: Therefore, the answer to the question is that the phenomenon by which an element occurs in different physical modifications in the same physical state is called **allotropy**.

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