Which of the following processes is $NOT$ involved in the extraction of metal from cassiterite $(SnO_2)$ ore?

Copper matte is composed of . . . . . .

Explain the following:
$(a)$ $CO_2$ is a better reducing agent below $710 \ K$ whereas $CO$ is a better reducing agent above $710 \ K$.
$(b)$ Generally,sulphide ores are converted into oxides before reduction.
$(c)$ Silica $(SiO_2)$ is added to the sulphide ore of copper in the reverberatory furnace.
$(d)$ Carbon and hydrogen are not used as reducing agents at high temperatures for certain metals.
$(e)$ Vapour phase refining method is used for the purification of $Ti$.

What is the approximate ratio of roasted ore,coke and limestone respectively in the charge to be added into the blast furnace for the extraction of iron?

In the electrolysis of $Al_2O_3$ by the Hall-Heroult process,which of the following statements is correct?

Ellingham diagrams can be drawn for which of the following?