Question

Which of the following molecule doesn't have a lone pair?

• A. ${\mathrm{BeCl}}_2$
• B. ${\mathrm{H}}_2\mathrm{O}$
• C. $\mathrm{HF}$
• D. ${\mathrm{NH}}_3$

Answer 1

The correct option is A

${\mathrm{BeCl}}_2$

Explanation for Correct option :

(A) ${\mathrm{BeCl}}_2$

Beryllium(Be) has two valence electrons in the valence shell so it can make only two bonds, which is already made with chlorine (Cl) So has no lone pair of the electrons. Structure can be shown as:

Explanation for incorrect options

(B)${\mathrm{H}}_2\mathrm{O}$

Oxygen (O) has six valence electrons in the valence shell, here oxygen uses its two electrons to form a single bond with hydrogen so it has two lone pairs of electrons. The structure of water can be shown as:

(C) $\mathrm{HF}$

Fluorine (F) has seven valence electrons in the valence shell, here fluorine uses one electron to form a single bond with hydrogen so it has three lone pairs of electrons. The structure is shown as:

(D)${\mathrm{NH}}_3$

Nitrogen (N) has five valence electron in the valence shell, here nitrogen use its three electrons to form a single bond with hydrogen , so it has one lone pair of electron which can be shown as: