Among the following compounds,the number of those present in copper matte is $......$
$A.$ $CuCO_3$
$B.$ $Cu_2S$
$C.$ $Cu_2O$
$D.$ $FeO$

Among statements $(a)-(d),$ the correct ones are
$(a)$ Limestone is decomposed to $CaO$ during the extraction of iron from its oxides.
$(b)$ In the extraction of silver,silver is extracted as an anionic complex.
$(c)$ Nickel is purified by Mond's process.
$(d)$ $Zr$ and $Ti$ are purified by Van Arkel method.

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

Type metal is an alloy of $Pb, Sb$ and $Sn$. It consists of

Railway wagon axles are made by heating iron rods embedded in charcoal powder. This process is known as:

In the metallurgy of iron,when limestone is added to the blast furnace,the calcium ions end up in: