Given the electronegativities below, which covalent single bond is most polar?
element: h c n o
electronegativity: 2.1 2.5 3.0 3.5
a) n-h b) o-c c) o-n d) c-h e) o-h

So the correct answer is e) O-H

Explanation:

To determine the most polar bond we calculate the electronegativity difference in each bond and determine the highest value:

a) N-H = 3.0 - 2.1 = 0.9

b) O-C = 3.5 - 2.5 = 1

c) O-N = 3.5 - 3 = 0.5

d) C-H = 2.5 - 2.1 = 0.4

e) O-H = 3.5 - 2.1 = 1.4

So the correct answer is e) O-H