Answer:
The answer to your question is: b. P - Br
Explanation:
Difference of electronegativities from the periodic table. The one with the highest electronegativity will be the most polar.
a.
H = 2.2
Se = 2.55
Electronegativity = 2.55 - 2.2 = 0.35
b.
P = 2.19
Br = 2.96
Electronegativity = 2.96 - 2.19 = 0.77
c.
N = 3.04
I = 2.66
Electronegativity = 3.04 - 2.66 = 0.38