The electronic configuration ofhte elements. A, B and C are given below. Answer the question from 14 to 17 on the basis of these configuration.
`{:(A,1s^(2),2s^(2),2p^(6),,),(B,1s^(2),2s^(2),2p^(6),3s^(2),3p^(3)),(C,1s^(2),2s^(2),2p^(6),3s^(2),3p^(5)):}`
Stable form of C may be represented by the formula

Options

A. C
B. `C_(2)`
C. `C_(3)`
D. `C_(4)`

Explanation

To determine the stable form of element C based on its electronic configuration, we will follow these steps:

### Step 1: Identify the Electronic Configuration of Element C
The electronic configuration of element C is given as:
\[ 1s^2, 2s^2, 2p^6, 3s^2, 3p^5 \]

### Step 2: Determine the Valence Electrons
From the electronic configuration, we can see that the outermost shell (n=3) contains:
- 2 electrons in the 3s subshell
- 5 electrons in the 3p subshell

Thus, the total number of valence electrons for element C is:
\[ 2 (from \, 3s) + 5 (from \, 3p) = 7 \, valence \, electrons \]

### Step 3: Identify the Group of Element C
Element C has 7 valence electrons, which indicates that it belongs to Group 17 of the periodic table, also known as the halogens.

### Step 4: Determine the Stability of Element C
Halogens are known to be one electron short of achieving a stable noble gas configuration. Since element C has 7 valence electrons, it needs 1 more electron to complete its octet and achieve stability.

### Step 5: Predict the Stable Form of Element C
To achieve a stable electronic configuration, element C will tend to gain one electron. When it gains one electron, it will have a complete octet, resembling the nearest noble gas configuration (in this case, Argon).

### Conclusion: Write the Stable Form of Element C
The stable form of element C can be represented as:
\[ C^- \]
This indicates that element C has gained one electron and is now in a stable ionic form.

### Final Answer
The stable form of C may be represented by the formula \( C^- \).

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