Answer:
a)
b)
Explanation:
a) The reaction:

The free-energy expression:

![E=E_{red}-E_{ox]](https://tex.z-dn.net/?f=E%3DE_%7Bred%7D-E_%7Box%5D)
The element wich is reduced is the Fe and the one that oxidates is the Mg:

The electrons transfered (n) in this reaction are 2, so:


b) If you have values of enthalpy and enthropy you can calculate the free-energy by:

with T in Kelvin


D because Carbon and Oxygen form covalent compounds. I wasn't the greatest at chem., but I'm pretty sure this is correct :D let me know if I gave you the right answer.
Answer:
A
Explanation:
they move to create more energy witch keeps them moving