The correct order of $\mathrm{X}-\mathrm{X}$ bond length in ${\mathrm{Cl}}_2^{+},{\mathrm{Cl}}_2$ and ${\mathrm{Cl}}_2^{-}$follows the order?

Because $\mathrm{Cl}$ is less electronegative than F and F has a higher electronegativity, which leads F and F to oppose one another, ${\mathrm{F}}_2$ has a lower bond dissociation enthalpy than ${\mathrm{Cl}}_2$.

Bond length $\propto \frac{1}{ \mathrm{Bond} \mathrm{order}}$and

Bond order of $C{l}_2⟶1$

$C{l}_2^{+}⟶1.5$

$C{l}_2^{-}⟶0.5$

Bond length grows as bond order gets smaller.