Baking soda `(NaHCO_(3))` is a compound because

Options

A. the constituents retain their properties.
B. the constituents van be separated by physical methods.
C. the constituents are combined chemically.
D. it is heterogeneous in nature.

Explanation

To determine why baking soda (NaHCO₃) is classified as a compound, we can analyze the characteristics of compounds and the options provided.

### Step-by-Step Solution:

1. **Understanding Compounds**:
- A compound is a substance formed when two or more elements are chemically bonded together. The properties of the compound differ from those of the individual elements.

2. **Analyzing the Options**:
- We are given four options:
1. The constituents retain their property.
2. The constituents can be separated by physical methods.
3. The constituents are combined chemically.
4. It is heterogeneous in nature.

3. **Evaluating Each Option**:
- **Option 1**: The constituents retain their property.
- This is incorrect for compounds. In a compound, the individual elements do not retain their original properties.
- **Option 2**: The constituents can be separated by physical methods.
- This is also incorrect. Compounds cannot be separated into their constituent elements by physical means; they require chemical reactions.
- **Option 3**: The constituents are combined chemically.
- This is correct. Baking soda (NaHCO₃) is formed from sodium (Na), hydrogen (H), carbon (C), and oxygen (O) through a chemical reaction.
- **Option 4**: It is heterogeneous in nature.
- This is incorrect. Compounds are homogeneous in nature, meaning they have a uniform composition throughout.

4. **Conclusion**:
- The correct answer is **Option 3: The constituents are combined chemically**. This indicates that baking soda is indeed a compound because it is formed through a chemical reaction where the elements are chemically bonded.

### Final Answer:
Baking soda (NaHCO₃) is a compound because the constituents are combined chemically.

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