Ncert Exercises & Solutions

Which of the following binary mixtures will have the same composition in the liquid and vapour phase?

(a)	Benzene-toluene	(b)	Water-nitric acid
(c)	Water-ethanol	(d)	n-Hexane-n-heptane

The correct choice is:

1.	a and b	2.	b and c
3.	c and d	4.	a and d

Hint: Water-nitric acid and Water-ethanol are azeotropes

Mixtures having the same composition in the liquid and vapour phase are known as azeotropes. Azeotropes boil at the same temperature.

Here, water-nitric acid and water-ethanol mixtures are the non-ideal solutions. Hence, water-nitric acid and water-ethanol are

examples of azeotropes.

While benzene-toluene and n-hexane and n-heptane are examples of an ideal solution.