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Which of the following is an example of oil in water emulsion?A. Cod liver oilB. ButterC. Cold creamD. Vanishing cream |
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Answer» Correct Answer - D Emulsions can be broadly classified into two types: (i) Oil in water emulsion (O/W type): In this type of emulsion, oil acts as dispersed phase and water acts as dispersion medium. Some examples of this type of emulsion are milk, vanishing cream, etc. In milk, liquid fat is dispersed in water. (ii) Water in oil emulsion (W/O type): In this type of emulsion, water acts as dispersed phase and oil (orangic solvent) acts as dispersion medium.Common examples of this type are butter, cold cream and cod liver oil. Cod liver oil is the oil expressed from the fresh liver of the cod, Gadus callarias. It is a pale yellow liquid, slightly soluble source of `A` and `D` vitamins and other food factors and is used in the prevention and cure of rickets in growing childern. The following tests may be employed to distinguish between the two types of emulsion: (i) Dye test: Some oil soluble dye is added to the emulsion, if the background becomes coloured, the emulsion is water-in-oil type. (ii) Dilution test: If the emulsion can be diluted with water, this indicates that water is the dispersion medium and the emulsion is of oil-in-water type. In case the added water forms a separate layer, the emulsion is water-in-oil type. |
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