Silver metal is extracted by cyanide process from silver glance `(Ag_(2)S)`. The ore is concentrated through forth floatation process. The concentrated ore is then leached and solution is treated with reducing agent to get spongy silver which is then purified by fusion with an oxidsing agent followed by electrolysis.
Leaching of `Ag_(2)S` is carried out by heating it with a dilute solution of
A. NaCN alone
B. NaCN in presence of `O_(2)`
C. HCl
D. NaOH
