Which of the following metals cannot be refined by distillation?

Tin

The correct answer is option 4. Tin.

Distillation is a process used to separate components of a mixture based on their differences in boiling points. In metallurgy, distillation is primarily used for purifying metals that have relatively low boiling points. Let's discuss why tin cannot be efficiently refined by distillation compared to the other metals mentioned.

Distillation Process:

Distillation works effectively when there is a significant difference in boiling points between the components of the mixture. During distillation, the mixture is heated to the boiling point of the component with the lowest boiling point. This component vaporizes and is then condensed back into a liquid form. For a metal to be efficiently refined by distillation, its boiling point should be within a reasonable temperature range for practical application. Metals with relatively low boiling points, such as zinc, cadmium, and mercury, fall within this range and can be effectively purified through distillation.

Tin has a considerably high boiling point of approximately 2602°C. The extremely high temperature required for distillation makes the process impractical and energy-intensive for refining tin on an industrial scale. Distillation at such high temperatures would also pose challenges in terms of equipment and energy consumption.Tin is typically refined using methods more suitable for high-temperature operations, such as smelting or electrolysis. These methods involve melting the tin ore and separating impurities by either chemical reactions or electrical processes.

While distillation is an effective method for purifying metals with lower boiling points, such as zinc, cadmium, and mercury, it is not practical for refining tin due to its considerably higher boiling point. Therefore, alternative methods like smelting or electrolysis are preferred for refining tin on an industrial scale.

Hence, tin cannot be efficiently refined by distillation compared to the other metals mentioned.