What is known as Thomas slag?

Which of the following processes is not used for the extraction of spelter from zinc blende?

Metals are extracted by other methods through the formation of complexes. The complexes formed in these methods are: $I$: Cyanide process,$II$: Mond process,$III$: Photographic fixing process.

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:

Which one of the following statements is incorrect?

Which of the following metals is present in Brass,Bronze,and German silver?