The furring of kettles is caused by the presence of what compound in water?
calcium tetraoxosulphate (IV)
calcium hydrogentrioxocarbonate (IV)
calcium hydroxide
calcium trioxocarbonate (IV)
Correct answer is D
Calcium hydrogen carbonate, often present in temporary hard water, is boiled in a kettle to remove the hardness. In the process, a scale forms on the inside of the kettle in a process known as furring of kettles. This scale is composed of calcium carbonate.