Which of the following statement is false for alkali metals ?

Options

A. lithium is strongest reducing agent
B. all alkali metals given blue solution in liquid ammonia
C. `Li^+` ion is exceptionally small
D. Lithium carbonate is stable towards heat and do not decompose

Answer

To determine which statement is false for alkali metals, let's analyze each statement one by one:

1. **Lithium is the strongest reducing agent.**
- Lithium has the most negative standard reduction potential among alkali metals, which means it can easily lose its electron and thus acts as a strong reducing agent. This statement is **true**.

2. **All alkali metals give blue solution in liquid ammonia.**
- When alkali metals are dissolved in liquid ammonia, they dissociate to form ammoniated electrons, which absorb visible light and impart a blue color to the solution. This statement is **true**.

3. **Li-Ion is exceptionally small.**
- Lithium ion (Li⁺) is indeed one of the smallest cations due to its small atomic size. This statement is **true**.

4. **Lithium carbonate is stable towards heat.**
- Lithium carbonate (Li₂CO₃) is known to decompose upon heating, especially at high temperatures, into lithium oxide (Li₂O) and carbon dioxide (CO₂). Therefore, this statement is **false**.

Based on the analysis, the false statement regarding alkali metals is that "Lithium carbonate is stable towards heat."