Find the correct order of acid strengths of the following compounds

 

Electron-withdrawing substituents can increase acidity of a nearby atom, which increases with electronegativity and decreases with increasing distance to the atom.

For the compounds given:

$–{\mathrm{NO}}_2$ (meta) withdraws electrons, stabilises the phenoxide ion, hence acidity is increased.

Lower acidity in case of meta-isomer as compared to para isomer is explained by the fact $\mathrm{m}$-nitrophenoxide is stabilised by inductive effect only and no resonance effect operates with  $-{\mathrm{NO}}_2$ group.

Stability order: $\mathrm{F}>\mathrm{D}>\mathrm{E}>\mathrm{B}>\mathrm{C}>\mathrm{A}$.