Answer:
Chlorine (Cl)
Explanation:
The equation would be:
→ 
This is because no atom is lost in a reaction. Chlorine would be the missing chemical as it is on the other side of the equation and needs to be accounted for on the products side.
The density of it would be 57. Do the math and apply the formula to it and you would get this answer.
Answer:

FCI=88.0818 MM≅88 MM
Explanation:
Empirical correlation based on the work of Bridgwater and Mumford (1979):
For Liquid or solid phase Plants:
F<60,000 tonne/yr Eq (1)
F≥60,000 tonnes/yr Eq (2)
Where:
N is the number of functional units
F is the process throughput tonnes/yr
In our case F=40,000 tonne/yr <60,000 tonne/yr, We are going to use Eq (1)
F<60,000 tonne/yr
N=8, F=40,000 tonne/yr

FCI=88.0818 MM≅88 MM
Possibly, Yes if it is proven