Which is main constitutent of egg-shell?

Options

A. `CaCO_(3)`
B. `CaSiO_(3)`
C. `CaSO_(4).(1)/(2)H_(2)O`
D. `CaSO_(4).2H_(2)O`

Answer

To determine the main constituent of an egg shell, we can analyze the options provided and identify which one is correct.

### Step-by-Step Solution:

1. **Understanding the Composition of Egg Shells**:
- Egg shells are primarily composed of various minerals. The most significant of these is calcium.

2. **Evaluating the Options**:
- **Option A: Calcium Carbonate (CaCO3)**:
- This is a common compound found in nature and is known to be the primary component of egg shells.
- **Option B: Calcium Silicate (CaSiO3)**:
- This compound is typically found in sand and is not a major component of egg shells.
- **Option C: Calcium Sulphate Hemihydrate (CaSO4·0.5H2O)**:
- Known as plaster of Paris, this compound is used in construction and is not related to egg shell composition.
- **Option D: Calcium Sulphate Dihydrate (CaSO4·2H2O)**:
- This is known as gypsum, which is also not a component of egg shells.

3. **Conclusion**:
- Based on the evaluation of the options, the main constituent of egg shells is **Calcium Carbonate (CaCO3)**. Therefore, the correct answer is **Option A**.

### Final Answer:
The main constituent of egg shell is **Calcium Carbonate (CaCO3)**.