Question

The number of electrons in the outermost shell in the atom of an inert element is:

• A. $0$
• B. $1$
• C. $2$
• D. $8$

Answer 1

The correct option is D

$8$

Explanation for the correct option:

Option D: $8$:

1. The outermost electron shell of an atom is called valence shell or valence orbit.
2. The electrons present in the outermost shell of an atom are called valence electrons.
3. The electronic configuration of any inert element has $8$ electrons in the valance shell except Helium $\mathbf{\left(}\mathbf{He}\mathbf{\right)}$ which has $2$ electrons in its valance shell.
4. For example: $\mathrm{Ar}=2,8,8$ ;$\mathrm{Ne}=2,8$ ;$\mathrm{He}=2$
5. As the valance electrons are $8$ their valency is $0$.

Explanation for the incorrect options:

Option A: $0$:

The electronic configuration of any inert element has $8$ electrons in the valance shell and not $0$.

Option B: $1$:

The electronic configuration of any inert element has $8$ electrons in the valance shell and not $1$.

Option C: $2$:

The electronic configuration of any inert element has $8$ electrons in the valance shell except Helium $\mathbf{\left(}\mathbf{He}\mathbf{\right)}$ which has $2$ electrons and not $2$.

Thus, Option (D) is the correct option.