Question

Which bond is most polar?

(1) H-H (2) H-C (3) H-N (4) H-F (5) H-Cl

Answer 1

$H-F$

is the most polar

Polarity refers to charge separation and electronegativity is conceived to be the ability of an atom involved in a chemical bond to polarize electron density towards itself. There are various scales of electronegativity, and the earliest, and still most widely used scale is the Pauling scale, which sets the electronegativity of fluorine at 4.0, of oxygen at 3.5, of nitrogen at 3.0, and of hydrogen at 2.2

.$Δ_{electronegativity}$ is a reasonable metric to assess the polarity of the resultant bond...and clearly the greatest electronegativity difference occurs for the H−F molecule.