Portland cement is manufactured by using:

Plaster of Paris when mixed with the correct amount of water sets into a solid mass due to the formation of

Identify the incorrect reaction.

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$ :
Assertion $(A)$ : $BeCl_2$ and $MgCl_2$ produce characteristic flame.
Reason $(R)$ : The excitation energy is high in $BeCl_2$ and $MgCl_2$.
In the light of the above statements,choose the correct answer from the option given below :

The number of electrons and protons in the third alkaline earth metal ion $(Ca^{2+})$ will be:

The commercial name for calcium oxide is