Choose incorrect statement:

Options

A. `BeCO_(3)` is kept in the atmosphere of `CO_(2)` since, it is least thermally stable
B. Be dissolves in alkali forming `[Be(OH)_(4)]^(2-)`
C. `BeF_(4)` forms complex ion with NaF in which Be goes with cation
D. `BeF_(4)` forms complex ion with NaF in which Be goes with anion

Answer

To solve the question of identifying the incorrect statement regarding beryllium and its compounds, we will evaluate each of the provided options step by step.

### Step 1: Analyze Option 1
**Statement:** BeCO3 is kept in the atmosphere of CO2 since it is least thermally stable.

**Explanation:** Beryllium carbonate (BeCO3) is indeed known to be thermally unstable. It decomposes upon heating to produce beryllium oxide (BeO) and carbon dioxide (CO2). Therefore, it is often stored in a CO2 atmosphere to prevent its decomposition.

**Conclusion:** This statement is correct.

### Step 2: Analyze Option 2
**Statement:** Beryllium dissolves in alkali forming Beryllium hydroxide ion.

**Explanation:** When beryllium reacts with alkali (such as sodium hydroxide), it forms the beryllium hydroxide ion, specifically Be(OH)4^2-. This reaction is well-documented and confirms that beryllium can indeed dissolve in alkaline solutions.

**Conclusion:** This statement is correct.

### Step 3: Analyze Option 3
**Statement:** BeF4 forms a complex ion with NaF in which Beryllium goes with the cation.

**Explanation:** Beryllium tetrafluoride (BeF4) can indeed form complex ions with sodium fluoride (NaF). However, the correct formation involves beryllium associating with the anion rather than the cation. The complex formed is Na2BeF4^2-, where beryllium is associated with the anionic part of the complex.

**Conclusion:** This statement is incorrect.

### Step 4: Analyze Option 4
**Statement:** BeF4 forms a complex ion with NaF in which beryllium goes with the anion.

**Explanation:** As discussed in the previous step, when BeF4 forms a complex with NaF, beryllium indeed associates with the anion, confirming this statement.

**Conclusion:** This statement is correct.

### Final Conclusion
After analyzing all the options, we find that the incorrect statement is **Option 3**, which claims that BeF4 forms a complex ion with NaF in which beryllium goes with the cation.

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