Question

Which of the following statements are true about an element having an atomic number of 11?

• A. It has 2 electrons in its K shell.
• B. It has 2 electrons in its M shell.
• C. It has 9 electrons in its L shell.
• D. It has 8 electrons in its L shell.

Answer 1

Answer: (A), (D)

It has 8 electrons in its L shell.

$\bullet$ The element which has atomic number 11 is sodium.

$\bullet$ The maximum number of electrons that can be accommodated in the ${\text{n}}^{\text{th}}$ shell of any atom is given by $2$ $\times$ ${\text{n}}^2$. The electronic configuration of sodium is as follows.
$$\begin{array}{cccc}\text{Shell}& \text{K}& \text{L}& \text{M}\\ \text{No. of electrons}& \text{2}& \text{8}& \text{1}\end{array}$$
$\bullet$ So, sodium has 2 electrons in its K shell, 8 electrons in its L shell and 1 electron in its M shell.