Which among the following statements is true?

Options

A. Compounds are heterogeneous in nature.
B. The proportion of constituent elements in a compound is fixed.
C. The constituent elements retain their properties in a compound.
D. The formation of a compound is a physical process.

Explanation

To determine which among the statements is true regarding compounds, we can analyze each statement based on the properties of compounds as discussed in the video transcript.

### Step-by-Step Solution:

1. **Understanding Compounds**:
- Compounds are pure substances that consist of two or more different types of atoms chemically bonded together.
- Example: In sulfur dioxide (SO2), there is one sulfur atom and two oxygen atoms.

**Hint**: Remember that compounds are made of different atoms bonded together.

2. **Homogeneous Nature**:
- Compounds are homogeneous in nature, meaning their composition is uniform throughout.
- The ratio of the constituent atoms in a compound is fixed. For example, in SO2, the ratio of sulfur to oxygen is always 1:2.

**Hint**: Think of homogeneous substances as having a consistent composition.

3. **Properties of Constituent Elements**:
- When elements form a compound, they do not retain their individual properties. For instance, hydrogen and oxygen have different properties than water (H2O).

**Hint**: Consider how the characteristics of elements change when they combine to form a compound.

4. **Formation of Compounds**:
- The formation of a compound involves a chemical process, not a physical one. This is because chemical bonds are formed during the process.

**Hint**: Distinguish between chemical and physical processes—chemical processes involve bond formation.

5. **Evaluating Statements**:
- **Statement 1**: Compounds are heterogeneous in nature. (False)
- **Statement 2**: The proportion of the constituent elements in a compound is fixed. (True)
- **Statement 3**: The constituent elements retain properties in a compound. (False)
- **Statement 4**: The formation of a compound is a physical process. (False)

**Hint**: Review each statement carefully and compare it with the properties of compounds discussed.

### Conclusion:
The true statement among the options provided is: **The proportion of the constituent elements in a compound is fixed.**