Which of the following can be separated using fractional distillation: A) Nitrogen from liquid air B) Sodium Chloride from sea water C) Iodine from solution of iodine in carbon tetrachloride D) Sulphu

Fractional distillation is a process used to separate components of a liquid mixture that have different boiling points.

• A) Nitrogen from liquid air: Liquid air is a mixture of gases (primarily nitrogen and oxygen) that have been cooled to their liquid state. Nitrogen has a boiling point of $-196 \text{ °C}$, while oxygen has a boiling point of $-183 \text{ °C}$. Due to their different boiling points, nitrogen and oxygen can be separated from liquid air by fractional distillation. This is a common industrial process.
• B) Sodium Chloride from sea water: Sodium chloride is a non-volatile solid dissolved in water. This separation is typically done by evaporation or simple distillation, where water is boiled off, leaving the solid salt behind. Fractional distillation is not suitable for separating a non-volatile solid from a volatile liquid.
• C) Iodine from solution of iodine in carbon tetrachloride: Iodine is a solid dissolved in a liquid (carbon tetrachloride). This separation would typically involve evaporation or simple distillation to recover the solid iodine.
• D) Sulphur from the solution of sulphur in carbon disulphide: Sulphur is a solid dissolved in a liquid (carbon disulphide). Similar to option C, this separation would typically be achieved by evaporation or simple distillation.

Therefore, the only option that involves separating components with different boiling points from a liquid mixture, making fractional distillation an appropriate method, is the separation of nitrogen from liquid air.

The final answer is $\boxed{\text{A}}$