Which of the following is/are correct statement (s) regarding carbonates of alkaline earth metal ?
I. They are thermally unstable.
II. They are insoluble in water .
III.Beryllium carbonate is thermally unstable.

Options

A. II and III
B. Only II
C. I and II
D. All are correct

Answer

To solve the question regarding the carbonates of alkaline earth metals, we will evaluate each statement one by one.

### Step-by-Step Solution:

**Step 1: Evaluate Statement I**
- Statement I: "They are thermally unstable."
- Explanation: Carbonates of alkaline earth metals do decompose upon heating. For example, they typically break down into metal oxides and carbon dioxide. Therefore, this statement is **correct**.

**Step 2: Evaluate Statement II**
- Statement II: "They are insoluble in water."
- Explanation: Most carbonates of alkaline earth metals are indeed insoluble in water, with the exception of beryllium carbonate which is slightly soluble. As we move down the group, the solubility of carbonates increases, but they are generally considered to be insoluble. Thus, this statement is also **correct**.

**Step 3: Evaluate Statement III**
- Statement III: "Beryllium carbonate is thermally unstable."
- Explanation: Beryllium carbonate is known to be thermally unstable and decomposes upon heating. It is also stored in an atmosphere of carbon dioxide to prevent decomposition. Therefore, this statement is **correct**.

**Conclusion:**
All three statements (I, II, and III) regarding the carbonates of alkaline earth metals are correct. Thus, the correct answer is that all of these statements are correct.

### Final Answer:
All of the statements (I, II, and III) are correct regarding the carbonates of alkaline earth metals.

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