Consider the following statements: I. A colloid and a suspension are heterogeneous mixtures. II. Colloids can be separated from the mixture by the process of centrifugation. III. Particles of colloids and suspensions can be seen by naked eye. IV. The aqueous solution of copper sulphate does not show Tyndall effect; however, the mixture of milk and water shows Tyndall effect. Which of the statements given above is/are correct?
D. I, II and IV
Statement I is correct. Both colloids and suspensions are heterogeneous mixtures, even though colloids may appear homogeneous to the naked eye. Statement II is correct. The particles of a colloid are too small to be separated by ordinary filtration, but they can be separated using the process of centrifugation. Statement III is incorrect. While the particles of a suspension are large enough to be seen by the naked eye, the particles of a colloid are too small to be individually seen by the naked eye. Statement IV is correct. An aqueous solution of copper sulphate is a true solution and its particles are too small to scatter a beam of light, hence it does not show the Tyndall effect. A mixture of milk and water is a colloid, which contains particles large enough to scatter light, thus showing the Tyndall effect. Therefore, statements I, II, and IV are correct.
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