WAEC Chemistry 2020 Paper

Concept:Electronegativity is the tendency of an atom to attract shared electrons in a bond. The pair with the largest difference in electronegativity has the most ionic character.Explanation:Sodium has electronegativity $0.93$.The given halogens have these electronegativity values:Fluorine $= 4.0$Chlorine $= 3.0$Bromine $= 2.8$Iodine $= 2.5$Now calculate each difference with sodium:Na and F: $4.0 - 0.93 = 3.07$Na and Cl: $3.0 - 0.93 = 2.07$Na and Br: $2.8 - 0.93 = 1.87$Na and I: $2.5 - 0.93 = 1.57$The largest difference is $3.07$, which occurs between sodium and fluorine.Answer:A. Na and F