Which one is used as a by-product in Serpeck's process?

Observe the following statements:
Statement-$I$: The choice of reducing agent for the reduction of an oxide ore can be predicted by using Ellingham diagram,a plot of $\Delta G^{\ominus}$ vs $T$.
Statement-$II$: According to Ellingham diagram,metal oxide with higher $\Delta G^{\ominus}$ is more stable than the oxide with lower $\Delta G^{\ominus}$.

The alumino-thermite process is used for the metallurgy of which metal?

Which of the following has the lowest percentage of carbon?

In the process of obtaining cast iron from pig iron,the reverberatory furnace is lined with ..........

Out of $C$ and $CO$,which is a better reducing agent at $673 \, K$?