Question

When 2,4dinitrochlorobenzene is treated with sodium hydrooxide at 100c° followed by protonation

Answer 1

OH⁻ attacks the ipso carbon (the carbon bearing the leaving group). This destroys the aromaticity of the ring. But it forms a resonance-stabilized σ-complex in which the negative charge is delocalized around the ring and the O atoms of the nitro groups.