Alumino-thermic process is used for the metallurgy of:

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: In the Ellingham diagram,a sharp change in slope of the line is observed for $Mg \rightarrow MgO$ at $\sim 1120^{\circ} C$.
Reason $R$: There is a large change of entropy associated with the change of state.
In the light of the above statements,choose the correct answer from the options given below.

Which among the following is used as flux in the extraction of iron from oxide ores?

In the extraction of zinc,what burns to produce a blue flame?

Wrought iron is the purest form of iron. Write a reaction used for the preparation of wrought iron from cast iron. How can the impurities of sulphur,silicon and phosphorus be removed from cast iron?

Which of the following is used to remove silicon dioxide in the Serpeck's process for the purification of bauxite?