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.
