A. calcium tetraoxosulphate (IV)
B. calcium hydrogentrionocarbonate (IV)
C. calcium hydroxide
D. calcium trioxocarbonate (IV)
Correct Answer:
Option D – calcium trioxocarbonate (IV)
Explanation
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.

![A quantity of hot water at 100ºC is added to 400g of water at 10ºC until the temperature of the mixture is 60ºC. Calculate the mass of the hot water added. [Specific heat capacity of water =4200JKg-1 K-1] A quantity of hot water at 100ºC is added to 400g of water at 10ºC until the temperature of the mixture is 60ºC. Calculate the mass of the hot water added. [Specific heat capacity of water =4200JKg-1 K-1]](https://erudites.ng/wp-content/plugins/contextual-related-posts/default.png)