For a good quality cement, the ratio of lime to the total of the oxides of Si , Al and Fe should be as close as to

Step-by-step solution

Cement is made by strongly heating a mixture of lime stone and clay in a rotatory kiln. Lime stone and clay are finely powdered, and a little water is added. For a good quality cement, the ratio of silica ( SiO 2 ) to alumina ( Al 2 O 3 ) should be between 2 . 5 and 4 and the ratio of lime ( CaO ) to the total of the oxides of silicon ( SiO 2 ) aluminium ( Al 2 O 3 ) and iron ( Fe 2 O 3 ) should be as close as possible to 2 . If lime is in excess, the cement cracks during setting. On the other hand, if lime is less