Question

The liquid air in fractional distillation method separates depending on:
(A) Melting point
(B) Density
(C) Volume
(D) Boiling point

Answer 1

Hint :Fractional distillation is a method which is used to separate mixtures into different components. In case of liquid air, it usually involves compression of liquid air, cooling, filtration and at last passing it to the distillation column to warm it up.

Complete Step By Step Answer:
Fractional distillation is the process of separation of a mixture into its component parts, or their fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of that mixture vaporizes.

Fig.: Fractional distillation of liquid air
The liquid air in the fractional distillation method first gets compressed by increasing the pressure. Then, it is further cooled down by decreasing the temperature to again get the liquid air back. Sometimes, a filter might be used to remove the unnecessary gases, liquids or other particles from it. Now it is moved to a fractional distillation column to warm it up slowly. In this fractional distillation column, with the increase in temperature, gases start to get separated at different heights depending on their boiling points. The separated gases are obtained by the receiver ends from the fractional distillation column.
As we saw above liquid air gets separated depending on the boiling point of the gas.
Hence, option D is correct.

Note :
Whenever liquid air needs to be separated, fractional distillation is used. Focus on the steps involved in the separation of liquid air in fractional distillation. Making a diagram may help you to remember the steps correctly.