What is obtained when a mixture of $Cu_2O$ and $Cu_2S$ is heated?

In the electrolytic method of obtaining aluminium from purified bauxite,cryolite is added to the charge in order to

The cyanide process is used in the extraction of:

State the important features of Ellingham diagram. Also state its limitations.

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The reduction of a metal oxide is easier if the metal formed is in liquid state than solid state.
Reason $R$: The value of $\Delta G^{\ominus}$ becomes more on negative side as entropy is higher in liquid state than solid state.
In the light of the above statements,choose the most appropriate answer from the options given below.

Which of the following compounds is used for the extraction of aluminum by electrolysis?