The chemical bond between which two atoms is most polar?

(1) C-N (3) S-Cl

(2) H-H (4) Si-O

Correct Answer: option 4: Si-O

Reason:

The bond polarity depends on the electronegativity difference between constituent atoms. Greater the electronegativity difference, polar is the bond. In present case, electronegativity of Si and O is 1.9 and 3.44 respectively. Hence, electronegativity difference is 1.54, which is greater as compared to other bonds on present interest. Hence, Si-O bond is considered to be more polar.

(4) Si-O is the most polar, since their differences in electronegativity is the highest.