Which is incorrect statement about lithium and magnesium?

Options

A. Lithium and magnesium do not form superoxide
B. LiCl and MgCl, are soluble in ethanol
C. Li and Mg salts do not respond to flame test
D. Carbonates of Li and Mg decompose easily on heating

Answer

To determine which statement about lithium and magnesium is incorrect, we will analyze each of the four statements provided in the question.

### Step-by-Step Solution:

1. **Statement 1: Lithium and Magnesium do not form superoxide.**
- Lithium (Li) and Magnesium (Mg) indeed do not form superoxides. Instead, they form simple oxides when they react with oxygen.
- Lithium forms lithium oxide (Li2O) and magnesium forms magnesium oxide (MgO).
- **Conclusion:** This statement is correct.

2. **Statement 2: Lithium Chloride and MgCl2 are soluble in Ethanol.**
- Both lithium chloride (LiCl) and magnesium chloride (MgCl2) are ionic compounds. Ionic compounds are generally soluble in polar solvents.
- Ethanol is a polar solvent, and thus, lithium chloride and magnesium chloride are soluble in ethanol.
- **Conclusion:** This statement is correct.

3. **Statement 3: Lithium and Magnesium salts do not respond to flame test.**
- This statement is incorrect. Lithium salts do respond to flame tests and produce a characteristic red color when burned.
- Magnesium, however, does not produce a flame color because its outer electrons are tightly bound and require more energy to be excited than what is provided by a typical flame.
- **Conclusion:** This statement is incorrect.

4. **Statement 4: Carbonates of lithium and magnesium decompose easily on heating.**
- Lithium carbonate (Li2CO3) and magnesium carbonate (MgCO3) are known to be thermally unstable and decompose upon heating.
- Lithium carbonate decomposes into lithium oxide (Li2O) and carbon dioxide (CO2), while magnesium carbonate decomposes into magnesium oxide (MgO) and carbon dioxide (CO2).
- **Conclusion:** This statement is correct.

### Final Answer:
The incorrect statement is **Statement 3: Lithium and Magnesium salts do not respond to flame test.**

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