When silica is present as an impurity in an ore,a/an ........ flux is required.

The substance used in the thermite process of reducing metal ores is

The following reactions take place in the blast furnace during the preparation of impure iron. Identify the reaction pertaining to the formation of the slag.

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.

In the isolation of which one of the following metals from their ores,is the use of cyanide salt not commonly involved?

Why is sulphide ore of copper heated in a furnace after mixing with silica?