Increasing order of polarity in HF, HCl, HBr, HI is

Order of the polarity of the molecules depends on the electronegativity of the bonded atoms. The E.N order for halogens is given below.

$\mathrm{F}>\mathrm{Cl}>\mathrm{Br}\ge \mathrm{I}$

Therefore, the order of polarity of hydrogen halide molecules is

$\mathrm{HI}<\mathrm{HBr}<\mathrm{HCl}<\mathrm{HF}$