Thermodynamic Principles of Metallurgy — Prelims Questions

Which of the following statements regarding the Ellingham diagram for metal oxides is INCORRECT?

At what approximate temperature does carbon become a more effective reducing agent than carbon monoxide for iron oxides, according to a typical Ellingham diagram?

Which of the following metals cannot be extracted by reduction with carbon at high temperatures, based on thermodynamic principles?

For the reaction $2M(s) + O_2(g) \rightarrow 2MO(s)$, what would be the expected sign of $\Delta S$ and the slope of its Ellingham diagram line?

Consider the following reactions:\nI. $2C(s) + O_2(g) \rightarrow 2CO(g)$\nII. $2CO(g) + O_2(g) \rightarrow 2CO_2(g)$\nIII. $2Mg(s) + O_2(g) \rightarrow 2MgO(s)$\nWhich of these reactions would show a decreasing $\Delta G^\circ$ with increasing temperature on an Ellingham diagram?

Given the following standard Gibbs free energy changes for oxide formation at a certain high temperature T:\n$\Delta G^\circ (ZnO) = -350 \text{ kJ/mol}$ (for $Zn + \frac{1}{2}O_2 \rightarrow ZnO$)\n$\Delta G^\circ (CO) = -400 \text{ kJ/mol}$ (for $C + \frac{1}{2}O_2 \rightarrow CO$)\nWhich of the following statements is correct regarding the reduction of $ZnO$ by carbon at temperature T?