The form of iron obtained from blast furnace is

Copper can be extracted by hydrometallurgy but not zinc. Explain.

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.

The cyanide process is used in the extraction of:

Upon heating with $Cu_2S$,the reagent$(s)$ that give copper metal is/are:
$(A)$ $CuFeS_2$
$(B)$ $CuO$
$(C)$ $Cu_2O$
$(D)$ $CuSO_4$

Which of the oxide groups among the following cannot be reduced by carbon?