To find out the electronegativity of each pair, work it out by listing them. H = 2.2 S = 2.1 N = 3.0 Cl = 3.0 O = 3.5 C = 2.5 H – S -> 2.2 - 2.1 = 0.1 H – Cl -> 2.2 - 3.0 = -0.8 N – H -> 3.0 - 2.2 = 0.8 O – H -> 3.5 - 2.2 = 1.3 C – H-> 2.5 - 2.2 = 0.3 So, the pairs that has the highest electronegativity is H-Cl and N-H.
