o-nitroaniline is eluted first due to the polarity of it and the
silica
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The mixture of o-Nitroaniline and P-Nitroaniline can be
separated using liquid chromatography because they have close
solubility.
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It reacts with the acidic conditions (since the NH2 is basic) to
form the meta-directing electron withdrawing group NH3. This forms
the meta-nitroaniline.