The best method for the separation of o -nitrophenol and p -nitrophenol from their mixture is:

Step-by-step solution

o -nitrophenol and p -nitrophenol can be separated by steam distillation based on the difference in their volatility. o -nitrophenol exhibits intramolecular hydrogen bonding, which reduces its intermolecular forces of attraction, making it more volatile and capable of being steam distilled. p -nitrophenol exhibits intermolecular hydrogen bonding, leading to the formation of associated molecules, which significantly increases its boiling point and makes it less volatile. Therefore, o -nitrophenol distills over with