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?

Statement I is correct: Both colloids and suspensions are heterogeneous mixtures, though colloids may appear homogeneous to the naked eye. Statement II is correct: Colloidal particles are small enough to pass through filter paper but can be separated from the solvent using centrifugation. Statement III is incorrect: While suspension particles are large enough to be seen by the naked eye, colloidal particles (typically 1 to 1000 nm) are too small to be seen individually without a microscope. Statement IV is correct: Copper sulphate forms a true solution, which does not scatter light. Milk is a colloid that scatters light, demonstrating the Tyndall effect. Thus, statements I, II, and IV are correct.