The existence of two or more forms of a compound is called .....................

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks for the term that describes the existence of two or more forms of a compound.

2. **Identifying the Concept**: The concept that relates to the existence of different forms of a compound is known as "allotropy".

3. **Defining Allotropy**: Allotropy is the phenomenon where an element can exist in more than one physical form. These different forms are referred to as allotropes.

4. **Examples of Allotropes**: Carbon is a well-known element that exhibits allotropy. Its allotropes include:
- Graphite
- Diamond
- Fullerenes
- Charcoal
- Coke

5. **Characteristics of Allotropes**:
- **Graphite**: Has a two-dimensional layered structure where each carbon atom is bonded to three other carbon atoms.
- **Diamond**: Has a three-dimensional tetrahedral structure where each carbon atom is bonded to four other carbon atoms.
- **Fullerenes**: Have a unique structure resembling a football, composed of hexagonal and pentagonal rings.
- **Charcoal and Coke**: These are amorphous allotropes, meaning they lack a definite shape or crystalline structure.

6. **Conclusion**: Therefore, the term that describes the existence of two or more forms of a compound is called **allotropy**.

---