In the leaching of $Ag_2S$ with $NaCN$,a stream of air is also passed. This is because of:

Which of the following is not correctly matched?

Consider the following statements:
$(a)$ When the lead-silver alloy is rich in silver,lead is removed by the cupellation process.
$(b)$ Froth flotation can be applied for non-sulphide ores also using a suitable activator.
$(c)$ $PbSO_4 + H_2SO_4$ electrolyte is used for the refining of $Pb$ by electrolysis.
$(d)$ Any metal will not reduce the oxide of other metals which lie above it in the Ellingham diagram.
Using $'T'$ for true and $'F'$ for false statements in the given sequence,select the correct set of code.

Gun metal is an alloy of

Metallurgy is the process of

The major components of German Silver are: