Which of the following electronic configuration in the outermost
shell is characteristic of alkali metals?

Options

A. `(n-1)s^(2)p^(6)ns^(2)np^(1)`
B. `(n-1)s^(2)p^(6)d^(10)ns^(1)`
C. `(n-1)s^(2)p^(6)ns^(1)`
D. `ns^(2)np^(6)(n-1)d^(10)`

Explanation

To determine the electronic configuration characteristic of alkali metals, we need to analyze the outermost shell configuration of these elements.

### Step-by-Step Solution:

1. **Identify Alkali Metals**:
Alkali metals are located in Group 1 of the periodic table. The elements in this group include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

2. **Understand Electronic Configuration**:
The general electronic configuration of alkali metals can be represented as:
\[ \text{[Noble Gas]} \, ns^1 \]
where \( n \) represents the principal quantum number of the outermost shell.

3. **Analyze the Outermost Electron**:
In alkali metals, the last electron enters the s-orbital of the outermost shell. This means that there is one electron in the outermost shell, which is characteristic of alkali metals.

4. **Examples of Electronic Configurations**:
- **Lithium (Li)**: \( 1s^2 \, 2s^1 \)
- **Sodium (Na)**: \( 1s^2 \, 2s^2 \, 2p^6 \, 3s^1 \)
- **Potassium (K)**: \( 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^1 \)
- **Rubidium (Rb)**: \( 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2 \, 4p^6 \, 5s^1 \)
- **Cesium (Cs)**: \( 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2 \, 4p^6 \, 5s^2 \, 5p^6 \, 6s^1 \)

5. **Conclusion**:
From the analysis, we can conclude that the characteristic electronic configuration for the outermost shell of alkali metals is \( ns^1 \), where \( n \) can vary depending on the specific alkali metal.

### Final Answer:
The electronic configuration in the outermost shell characteristic of alkali metals is \( ns^1 \).