Answer: The correct answer is Option D.
Explanation: Unequal sharing of electrons between the elements means that the bond is polar. This is very well studied with the help of electronegativity difference.
More the electronegative difference, more polar will be the bond and more will be unequal sharing of electrons and vice-versa.
Electronegativity values of the given elements:
1. Aluminium and Chlorine
Electronegativity of Aluminium = 1.61
Electronegativity of Chlorine = 3.16
Electronegative difference of Aluminium and chlorine = (3.16 - 1.61) = 1.55
2. Lead and sulfur
Electronegativity of Lead = 2.33
Electronegativity of Sulfur = 2.58
Electronegative difference of Lead and sulfur = (2.58 - 2.33) = 0.25
3. Nitrogen and oxygen
Electronegativity of Nitrogen = 3.04
Electronegativity of Oxygen = 3.44
Electronegative difference of Nitrogen and oxygen = (3.44 - 3.04) = 0.4
4. Lithium and Chlorine
Electronegativity of Lithium = 0.98
Electronegativity of Chlorine = 3.16
Electronegative difference of Lithium and chlorine = (3.16 - 0.98) = 2.18
As, the electronegativity difference of lithium and chlorine is the highest, so there will be the highest unequal sharing of electrons. This is an ionic compound.
Hence, the correct answer is option 4.
