Which one of the following methods can be used to obtain highly pure metal which is liquid at room temperature ?

The correct option is Distillation.

Step-by-Step Explanation:

1. Identify the properties of the metal described: The question asks for a method to refine/purify a metal that is highly pure and is a liquid at room temperature. The only metal that is liquid at room temperature is mercury ($\mathrm{Hg}$). Gallium ($\mathrm{Ga}$) also has a very low melting point ($29.76{°}^C$) and can exist as a liquid near room temperature.

2. Analyze the refining methods:
• Distillation: This method is used for metals with low boiling points, such as zinc ($\mathrm{Zn}$), cadmium ($\mathrm{Cd}$), and mercury ($\mathrm{Hg}$). The impure metal is heated to evaporate the volatile metal, and the vapors are then condensed in a separate receiver to obtain the highly pure metal, leaving behind the non-volatile impurities.
• Electrolysis (Electrolytic refining): Used for metals like copper ($\mathrm{Cu}$), zinc ($\mathrm{Zn}$), and aluminium ($\mathrm{Al}$).
• Chromatography: Mainly used for the separation, identification, and purification of organic compounds or elements present in trace amounts, rather than bulk metal purification.
• Zone refining: Used to obtain metals of very high purity (like semiconductors, e.g., silicon ($\mathrm{Si}$), germanium ($\mathrm{Ge}$), and gallium ($\mathrm{Ga}$)) by exploiting the difference in solubility of impurities in the molten and solid states of the metal.

3. Conclusion: Since mercury ($\mathrm{Hg}$) is the liquid metal at room temperature and has a low boiling point ($356.7{°}^C$), it is purified using the distillation method.