Question

The correct sequence of increasing covalent character is represented by:
A.${\text{BeC}}{{\text{l}}_{\text{2}}}{\text{ < NaCl < LiCl}}$
B.${\text{NaCl < LiCl < BeC}}{{\text{l}}_2}$
C.${\text{BeC}}{{\text{l}}_{\text{2}}}{\text{ < LiCl < NaCl}}$
D.${\text{LiCl < NaCl < BeC}}{{\text{l}}_2}$

Answer 1

Hint: Electronegativity is defined as the tendency of an atom to attract a bonding pair of electrons.The atom which has high electronegativity will take the electrons and the atom which has low electronegativity will lose the electrons.
Bonds: In molecules atoms are linked together by bonds. Bonds are of many types, for example:

Complete step by step answer:
First of all we will talk about bonds.
-Ionic bond: The bond in the molecules which is formed by give and take of electrons i.e. one atom gives the electron and other atoms take the electron.
-Covalent bonds: The bond in the molecules in which the atoms share their electrons to each other. There are two types of covalent bonds: polar covalent bond and nonpolar covalent bond.
-Polar covalent bond: The covalent bonds in which the electronegativity difference of the two atoms is more i.e. one atom can attract the electron of another atom, are known as polar covalent bonds.
-Non-polar covalent bond: The covalent bonds in which the electronegativity difference of the two atoms is less i.e. one atom cannot attract the electron of another atom, are known as non-polar covalent bonds.
-Covalent character: It is defined as the tendency of an atom to attract electrons to itself, is known as covalent character. In the covalent bond when there is partial charge on the atoms then it is known as covalent character. The greater is the electronegativity difference between the atoms the greater will be the covalent character.
In the given molecules we can see that the anion attached to each molecule is the same i.e. chlorine but cations are different. And the order of electronegativity of the cations is as: ${\text{Na < Li < Be}}$. So the increasing order of the covalent character will be: ${\text{NaCl < LiCl < BeC}}{{\text{l}}_2}$.

So option B is correct.

Note:
As we move from top to bottom in a group of a periodic table then electronegativity of the elements increases and on moving left to right in a period of a periodic table the electronegativity increases as size increases.