If you place red litmus paper into a basic substance, it turn's blue. When it comes in contact with an acidic or neutral substance, it doesn't change colour it remains red.
Blue litmus paper in acid turns red when placed in a basic or neutral solution it remains blue. From this it can be concluded that the solution is neutral.
Water is said to be hard when it contains calcium ions or magnesium ions dissolved in it. These ions are able to react with soap in such a way that the soap is prevented from forming lather with the water. Hard water occurs when water passes over calcium or magnesium bearing minerals and dissolves some of it. Hardness due to the presence of calcium ions can easily be removed by boiling the water.
Explanation:Because of the delocalised electrons exposed above and below the plane of the rest of the molecule, benzene is obviously going to be highly attractive to electrophiles - species which seek after electron rich areas in other molecules.
