Which of the following is not true about alkali metals?

Options

A. Alkali metals do not occur free in nature.
B. Alkali metals are good oxidising agents.
C. Alkali metals salts impart colour to the flame
D. Alkali metal salts are generally ionic.

Explanation

To determine which statement is not true about alkali metals, we will analyze each option based on the properties and characteristics of alkali metals.

### Step-by-Step Solution:

1. **Understand the Electronic Configuration of Alkali Metals:**
- Alkali metals have the general electronic configuration of \( ns^1 \), where \( n \) is the principal quantum number corresponding to the outermost shell. This means they have one electron in their outermost shell.

2. **Behavior of Alkali Metals:**
- Since alkali metals have one electron in their outermost shell, they tend to lose this electron easily to achieve a stable noble gas configuration. For example, sodium (Na) has the configuration \( 1s^2 2s^2 2p^6 3s^1 \). When it loses one electron, it becomes \( Na^+ \) with the configuration \( 1s^2 2s^2 2p^6 \) (the same as neon).

3. **Reducing Agent Property:**
- Alkali metals act as reducing agents because they readily lose an electron (get oxidized) and can reduce other substances. This means they cannot act as oxidizing agents.

4. **Occurrence in Nature:**
- Alkali metals do not occur freely in nature due to their high reactivity. They are usually found in compound forms rather than as free elements.

5. **Flame Colors:**
- Alkali metal salts impart characteristic colors to flames when heated, which is a true statement.

6. **Nature of Alkali Metal Salts:**
- Alkali metal salts are generally ionic in nature because they form cations (e.g., \( Na^+ \)) when they lose their outermost electron.

7. **Identify the Incorrect Statement:**
- Based on the analysis, the statement that alkali metals act as oxidizing agents is not true. They are reducing agents instead.

### Conclusion:
The statement that is not true about alkali metals is that they act as oxidizing agents.

### Answer:
**The incorrect statement is: Alkali metals act as oxidizing agents.**

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