WAEC - Chemistry (1994 - No. 31)
Which of the following is likely to have the highest degree of hardness?
Carbonated water
Distilled water
Acidified water
Rain water
Lime water
Explication
Hardness in water is mainly due to the presence of dissolved minerals such as calcium and magnesium ions, carbonated water, and rainwater with added carbon dioxide either naturally or artificially do not contain a great amount of these dissolved minerals hence they are less likely to have a high degree of hardness compared to lime water which contains calcium ions from the dissolved calcium hydroxide.