Answer:
The electron configuration for calcium is: 1s2 2s2 2p6 3s2 3p6 4s2. Since calcium is in the fourth row and the second column of the s-block on the periodic table of elements, its electron configuration ends in 4s2. Every lower orbital is filled, starting with the 1s orbital.
Explanation:hope this helps 
 
        
             
        
        
        
The type of reaction of Fe2O3 + 2SiO2 → Fe2Si2O7 would be that it is a synthesis reaction. It is a type of chemical reaction in which two or more simple substances combine to form a more complex product. Hope this answers the question.
        
                    
             
        
        
        
When water reaches its boiling point and turns into water vapor, the molecular structure of water remains the same. It is only the state of the substance that is changed in this process. I hope this helps you