What is the percentage $(\%)$ of silver in German silver?

The alloy,which contains $95 \%$ aluminium and small amounts of copper,magnesium and manganese is . . . . . .

Which of the following reactions does not occur in the Bessemer converter?

Consider the following:
Statement-$I$ : In the extraction of $Al$ by Hall-Heroult process,pure $Al_2O_3$ mixed with $Na_3AlF_6$ lowers its melting point and increases conductivity.
Statement-$II$ : Zirconium metal is purified by zone refining method.

Refractory materials are generally used in furnaces because

The correct statement$(s)$ related to processes involved in the extraction of metals is(are):
$(A)$ Roasting of Malachite produces Cuprite.
$(B)$ Calcination of Calamine produces Zincite.
$(C)$ Copper pyrites is heated with silica in a reverberatory furnace to remove iron.
$(D)$ Impure silver is treated with aqueous $KCN$ in the presence of oxygen followed by reduction with zinc metal.