Which one of the following bonds would you expect to be the most polar? a) B-H b) N-H c) P-H d) Al-H e) C-H

Option b) N-H is the bond that you can expect to be the most polar.

Explanation:

A polar covalent bond is the result of uneven distribution of the electrons involved in the covalent bond.

The polar character of a covalent bond is determined by the difference in the electronegativities of the atoms bonded.

The higher the electronegativity difference of the two bonded atoms the more polar the covalent bond is.

Then, you need to find and compare the electronegativies of the atoms bonded.

This is the list of electronetativities of every atom in the question:

H: 2.20 B: 2.04 N: 3.04 P: 2.19 Al: 1.61 C: 2.55

Using that list you can do these calculations:

Bond Electronegativity difference

a) B-H 2.20 - 2.04 = 0.16

b) N-H 3.04 - 2.20 = 0.84

c) P-H 2.20 - 2.19 = 0.01

d) Al-H 2.20 - 1.61 = 0.59

e) C-H 2.55 - 2.20 = 0.35

Thus, the greatest electronegativity difference is that of N - H, 0.84, which indicates that this is the most polar bond from the choices.