The percentage $(\%)$ of silver in the alloy German silver is:

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

Which of the following elements constitutes a major impurity in pig iron?

Select the correct statement.

Identify the correct statements from the following:
$I$. Brass is an alloy of copper and nickel
$II$. Bronze is an alloy of copper and zinc
$III$. German silver is an alloy of copper,zinc and nickel
$IV$. Brass is an alloy of copper and zinc

Consider the following metallurgical processes:
$I$. Heating impure metal with $CO$ and distilling the resulting volatile carbonyl (b.p. $43 \ ^oC$) and finally decomposition at $150 \ ^oC - 200 \ ^oC$ to get the pure metal.
$II$. Heating the sulphide ore in air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged metal sulphide.
$III$. Electrolysis of the molten electrolyte containing approximately equal amounts of the metal chloride and $NaCl$ to obtain the metal.
The processes used for obtaining magnesium,nickel and copper are respectively: