Arrange the bonds in order of increasing ionic character in the molecules: $LiF, K_2O, N_2, SO_2$ and $ClF_3$.

(N/A) The ionic character of a bond depends on the electronegativity difference between the bonded atoms. $A$ larger electronegativity difference corresponds to a higher ionic character.
Increasing order of ionic character: $N_2 < ClF_3 < SO_2 < K_2O < LiF$

$N_2$	$100 \%$ covalent (homonuclear),$0 \%$ ionic.
$SO_2$	Electronegativity difference: $|3.5 - 2.5| = 1.0$.
$ClF_3$	Electronegativity difference: $|4.0 - 3.0| = 1.0$.
$K_2O$	Electronegativity difference: $|3.5 - 0.8| = 2.7$ (highly ionic).
$LiF$	Electronegativity difference: $|4.0 - 1.0| = 3.0$ (maximum ionic character).

Comparing $SO_2$ and $ClF_3$ (both have $\Delta EN = 1.0$): Based on Fajan's rule,smaller cations and larger anions increase covalent character. $S^{2+}$ is smaller than $Cl^{+}$,and $O^{2-}$ is larger than $F^{-}$,making $ClF_3$ more covalent than $SO_2$. Thus,$SO_2$ has slightly more ionic character than $ClF_3$.