In the alumino-thermite process,what does $Al$ act as?

In the electrolysis of aluminium oxide,which of the following is added to accelerate the process?

The electrolytic method of reduction is employed for the preparation of metals that

Tin is obtained from cassiterite by reduction with coke. Use the data given below to determine the minimum temperature (in $K$) at which the reduction of cassiterite by coke would take place.
At $298 \ K$: $\Delta_{f}H^{\circ}(SnO_{2(s)}) = -581.0 \ kJ \ mol^{-1}$,$\Delta_{f}H^{\circ}(CO_{2(g)}) = -394.0 \ kJ \ mol^{-1}$
$S^{\circ}(SnO_{2(s)}) = 56.0 \ J \ K^{-1} \ mol^{-1}$,$S^{\circ}(Sn_{(s)}) = 52.0 \ J \ K^{-1} \ mol^{-1}$
$S^{\circ}(C_{(s)}) = 6.0 \ J \ K^{-1} \ mol^{-1}$,$S^{\circ}(CO_{2(g)}) = 210.0 \ J \ K^{-1} \ mol^{-1}$
Assume that the enthalpies and the entropies are temperature independent.

Extraction of aluminium from bauxite ore,reduction is carried out by

Copper matte contains