10.21 Describe the importance of the following : (i) limestone (ii) cement (iii) plaster of paris.

Answers (1)
R Rakesh

(i) Limestone- 

The chemical formula is CaCO_{3}

Importance of limstone is-

  • It is used as a building material in the form of marble and in the manufacture of quick lime
  • Calcium carbonate along with magnesium carbonate is used as a flux in the extraction of metals such as iron. 
  • It is also used as an antacid, mild abrasive in tooth paste, a constituent of chewing gum, and a filler in cosmetics. 

(ii) Cement- 

 Cement is an important building material. It is amixture of triclcium silicate(Ca_{3}SiO_{5}) and tricalium aluminate(Ca_{3}Al_{2}O_{6}).

Importance of cement-

It is used in concrete and reinforced concrete, in plastering and in the construction of bridges, dams and buildings

(iii) Plaster of Paris-

It is a hemihydrate of calcium sulphate. It is obtained when gypsum, CaSO_{4}.2H_{2}O, is heated to 393 K. 

Importance of POP-

It is used in medicine as surgical bandages and also it is used for making casts and moulds.