A magnet can attract materials that are magnetic, such as iron, nickel, or cobalt. Among the common mixtures, if one of the components is a magnetic material like iron, the magnet will attract the magnetic material and separate it from the non-magnetic materials. In the case of a mixture of iron filings and sand, the iron filings will be attracted to the magnet, while the sand will not, allowing for easy separation. Other mixtures like salt and water, sugar and flour, or oil and water do not contain any magnetic materials, so a magnet would not be effective in separating those.Answer by Mayor Niko