Which process is used to separate the ortho-nitrophenol and meta-nitrophenol?

Steam distillation

The correct answer is option 1. Steam distillation.

The ortho and para isomers can be separated by steam distillation.

Principle: Steam distillation is a technique used to separate substances that are volatile at temperatures significantly below their decomposition points.

Application: Ortho and para isomers of nitrophenol (such as ortho-nitrophenol and para-nitrophenol) have different solubilities in water due to their positional isomerism affecting their polarity and hydrogen bonding capabilities.

Process:

Steam Distillation: Steam is passed through the mixture of ortho and para isomers.

Separation: The para isomer (para-nitrophenol), being less soluble in water compared to the ortho isomer (ortho-nitrophenol), is preferentially distilled over with the steam.

Condensation: The vapor containing the para isomer and steam is condensed, and the separated compounds can be collected.

Therefore, it is correct that steam distillation can be used to separate ortho and para isomers of nitrophenol based on their different solubilities in water. This technique takes advantage of their positional isomerism affecting their physical properties, particularly their solubility.