D. HCIO4(AQ)
Hope this helps...
Answer:
a) 
b) 
c) 
Explanation:
Hello,
In this case, in each reaction we must subtract the Gibbs free energy of formation the reactants to the Gibbs free energy of formation of the products considering each species stoichiometric coefficients. In such a way, the Gibbs free energy of formations are:

So we proceed as follows:
a)

b)

c)

Regards.
Answer:
density = 4.763pounds per liter
Explanation:
1g/cm³ = 2.205pounds per liter
2.16g/cm³ = (unknown)pounds per liter
(unknown)pounds per liter = 2.205 x 2.16 = 4.763
density = 4.763pounds per liter
C. 2Fe2O3 would be the correct answer!