Question

The diagram shows a molecule hydrogen fluoride,

In the molecule,
A.The hydrogen and fluorine share a pair of electrons
B.The hydrogen and fluorine share a pair of protons
C.The hydrogen gives the fluorine an electron
D.The hydrogen gives fluorine a proton

Answer 1

Hint: The electron dot diagram or Lewis dot diagram is a structural representation of a molecule, in which the dots outside the common part represent a lone pair of electrons whereas dots inside the common part of the structure represent the number of electrons participating in the bond formation.

Complete answer:
The $HF$ molecule consist of a hydrogen and a fluorine atom whose electron configurations are given as follows:
Atomic number of Hydrogen $=2$
Electronic configuration $=1s^2$
Atomic number of fluorine $=9$
Electronic configuration $=1s^{2}2s^{2}2p^5$
As there is only one electron in the valence shell of hydrogen atom and there are seven electrons present in the valence shell of fluorine atom. So, in order to complete the valency or octet of each atom, both the atoms perform mutual sharing of their electrons and hence formation of a covalent bond takes place between the atoms.
The electron dot structure of hydrogen fluoride is represented as follows:

Where, circular electrons on the edge of a sphere represents the lone pair of electrons whereas the electrons represented with a circle and a cross represents the bond formed by mutual sharing of electrons.
Hence, in the molecule the hydrogen and fluorine share a pair of electrons.
Thus, option (A) is the correct answer.

Note:
According to octet rule, the main group elements tend to form a chemical bond in such a manner that the octet of the atom is completed i.e., each atom must have eight electrons in its valence shell after the formation of the bond.