Question

Which among the following gaseous mixtures can be separated by fractional evaporation?

• A. ${\mathrm{H}}_2+{\mathrm{SO}}_2$
• B. $\mathrm{CO}+{\mathrm{CO}}_2$
• C. ${\mathrm{NH}}_3+{\mathrm{SO}}_2$
• D. ${\mathrm{O}}_2+{\mathrm{N}}_2$

Answer 1

The correct option is D

${\mathrm{O}}_2+{\mathrm{N}}_2$

Explanation for the correct option: (D)

• Fractional distillation is a technique for separating the constituents of a liquid-liquid mixture with a boiling point difference of less than $25°\mathrm{C}$.
• The air we breathe is a homogeneous mixture of many different gases, including Carbon dioxide $\left({\mathrm{CO}}_2\right),$ Nitrogen $\left({\mathrm{N}}_2\right),$ Oxygen $\left({\mathrm{O}}_2\right),$ Argon $\left(\mathrm{Ar}\right)$ and others. Because their boiling points differ, the air is separated using the fractional distillation process.
• So, Oxygen gas $\left({\mathrm{O}}_2\right)$ can be separated out in the mixture of ${\mathrm{O}}_2+{\mathrm{N}}_2$ (Oxygen and Nitrogen) as their boiling point's difference is $13°\mathrm{C}.$

Explanation for the incorrect options:

A. In the mixture of ${\mathrm{H}}_2+{\mathrm{SO}}_2$ (Hydrogen and Sulfur dioxide), gases can not be separated out as their boiling point's difference is $113°\mathrm{C}.$

B. In the mixture of $\mathrm{CO}+{\mathrm{CO}}_2$ ( Carbon monoxide and Carbon dioxide), gases can not be separated out as their boiling point's difference is $26°\mathrm{C}.$

C. In the mixture of ${\mathrm{NH}}_3+{\mathrm{SO}}_2$ (Ammonia and Sulfur dioxide), gases can not be separated out as their boiling point's difference is $243°\mathrm{C}.$

Conclusion: Hence, the correct option is (D).