Explain: (1) A mixture of ether and water can be separated by simple distillation.
(2) Water present in rectified spirit can be removed by azeotropic distillation.
(3) Benzoic acid can be extarced from its aqueous solution using benzene.
(4) Sugar containing NaCI as impurity can be purified by crystallisation using ethanol but not water. '

Explanation

(1) There is a considerable differecne between the boiling points of ether and water. Hence, at the boiling point of more volatile ether, the vapours almost exclusively consist of ether and at the vapours almost entirely consist of water. Thus, these can be separated by simple distillation.
(2) A mixture of water and rectified spirit forms an azeotropic mixture, i.e. the constituents of this mixture cannot be separated into theier components by fractional distillation. So, azeotropic distillation is required to remove water from rectified spirit.
(3) Benzene is immiscible with water but benzoic acid is highly soluble in benzene, . Hence benzoic acid can be extracted from its aqueous solution using benzene.
(4) Sugar is soluble in hot ethanol whereas common salt remains insoluble. Thus, impure sugar can be purified by crystallisation. However, the purification both the components become readily soluble in water.