10 points! Which is the most polar bond

I-Br, S-O, F-F, K-Cl, O-Cl

K-Cl

Look at a table of electronegativities and calculate the difference in the electronegativities of the atoms in each bond.

K-Cl would have the largest difference and so be the most polar--to the point that it is an ionic compound.

KCl
It is so polar it is ionic