Which of the following in incorrect ?

Options

A. Cement containing no iron is white.
B. Cement containing excess amount of lime cracks during setting.
C. Setting of cement is and endothermic process.
D. Setting of cement is an example of hydration.

Answer

C

Explanation

When mixed with water, the setting of cement, an exothermic process, taken place to give a hard mass. This is due to the hydration of molecules of the constituents andtheir rearrangement. The resulting hard mass has three-dimensional network structure involving `-Si-O-Si` and `-Si-O-Al-` chains.
The purpose of adding gypsum is only to slow down the process of setting of the cement so that it gets sufficiently hardened. small amount of MgO (magnesia) and `Fe_(2)O_(3)` are required for imparting suitable color to cement.