A brand of ink containing cobalt (III), copper (II) and iron(II) ions can best be...

Explanation

In this question, we are asked to determine the best method to separate a mixture of ink containing cobalt (III), copper (II), and iron (II) ions. The correct answer is chromatography.

Chromatography is a separation technique used to separate the components of a mixture based on their different affinities towards a stationary phase and a mobile phase. In the case of ink, the components have different affinities towards a stationary phase (usually a solid or a coated paper) and a mobile phase (usually a solvent or a gas).

Let's briefly discuss the other options and why they are not suitable for this separation:

Option A: Fractional crystallization is a method used to separate components of a mixture based on their solubilities. While it can be effective for separating certain mixtures, it may not be the best method for separating ink components, as the ions may have similar solubilities and thus would not separate efficiently.

Option B: Fractional distillation is used to separate components of a mixture based on their boiling points. This method is more suitable for separating mixtures of liquids (such as different components in crude oil) rather than ink components, which are usually solids dissolved in a liquid.

Option C: Sublimation is the process of a solid transitioning directly into a gas without passing through a liquid phase. This method is not suitable for separating the ink components, as cobalt (III), copper (II), and iron (II) ions are not known to undergo sublimation.

In conclusion, chromatography is the most appropriate method for separating the components of a mixture of ink containing cobalt (III), copper (II), and iron (II) ions, as it is based on their different affinities towards a stationary phase and a mobile phase, making it a highly effective and precise separation technique.