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

The correct answer is Distillation.

Reasoning step‑by‑step:

1. Identify the metal that is liquid at room temperature. The only elemental metal that is naturally liquid near 25 °C is mercury (Hg).

2. To obtain a highly pure sample of a liquid metal, we need a technique that can separate the metal from impurities based on differences in volatility.

3. Distillation exploits the fact that mercury has a relatively low boiling point (≈ 356 °C) compared to most solid impurities, which either have much higher boiling points or decompose before reaching mercury’s boiling point. By heating the impure mercury, it vaporizes, leaving non‑volatile contaminants behind. The vapour is then condensed back into a liquid, yielding highly pure mercury.

4. The other listed methods are unsuitable for this purpose:

  • Zone refining works only on solid metals, moving a molten zone along a solid rod to purify it; it cannot be applied to a metal that is already liquid at room temperature.

  • Electrolysis deposits metals from aqueous or molten solutions, but it does not separate a liquid metal from solid impurities already present in the melt.

  • Chromatography separates chemical species in a mobile phase based on interactions with a stationary phase; it is not a technique for purifying bulk metallic liquids.

5. Therefore, the method that can be used to obtain a highly pure metal that is liquid at room temperature is distillation.