Select the incorrect statement:

Options

A. `Li_(2)CO_(3)` is only sparingly soluble in water and no `LiHCO_(3)` has been isolated.
B. `K_(2)CO_(3)` can not be made by a method similar to the solvey process
C. `Li_(2)CO_(3) and MgCO_(3)` both are thermally stable
D. `Na_(2)CO_(3). NaHCO_(3)*2H_(2)O` is a mineral called trona

Answer

To solve the question, we need to evaluate each statement regarding the properties of lithium carbonate, potassium carbonate, and their thermal stability. Let's go through the statements step by step:

### Step 1: Analyze Statement 1
**Statement:** Lithium carbonate is only sparingly soluble in water and no lithium bicarbonate has been isolated.

- **Explanation:** Lithium carbonate (Li2CO3) is indeed sparingly soluble in water due to the small ionic size of lithium, which leads to strong electrostatic attractions between lithium ions and carbonate ions. This strong attraction makes it less soluble. Additionally, lithium bicarbonate (LiHCO3) is not commonly isolated because it is unstable and decomposes easily.

- **Conclusion:** This statement is **correct**.

### Step 2: Analyze Statement 2
**Statement:** K2CO3 cannot be made by a method similar to the Solvay process.

- **Explanation:** The Solvay process is used to produce sodium carbonate (Na2CO3) from sodium chloride (NaCl) and ammonia. Potassium bicarbonate (KHCO3) is highly soluble in water, which means it does not precipitate out easily, making it unsuitable for the Solvay process. Therefore, K2CO3 cannot be produced using a similar method.

- **Conclusion:** This statement is **correct**.

### Step 3: Analyze Statement 3
**Statement:** Lithium carbonate and magnesium carbonate both are thermally stable.

- **Explanation:** Magnesium carbonate (MgCO3) is thermally stable and does not decompose easily upon heating. However, lithium carbonate (Li2CO3) is thermally unstable and decomposes when heated to form lithium oxide (Li2O) and carbon dioxide (CO2).

- **Conclusion:** This statement is **incorrect**.

### Step 4: Analyze Statement 4
**Statement:** Na2CO3.NaHCO3.2H2O is a mineral called Trona.

- **Explanation:** The chemical formula Na2CO3.NaHCO3.2H2O indeed represents Trona, a naturally occurring mineral. It is also known as trisodium hydrogen carbonate dihydrate.

- **Conclusion:** This statement is **correct**.

### Final Conclusion
The incorrect statement among the four provided is **Statement 3:** "Lithium carbonate and magnesium carbonate both are thermally stable."

### Summary of the Solution
- Statement 1: Correct
- Statement 2: Correct
- Statement 3: Incorrect (this is the answer)
- Statement 4: Correct