In the extraction of silver by Mac-arther cyanide process, a small of `KNO_(3)` is also added as a flux. The function of `KNO_(3)` is:

Options

A. to oxidise Ag in the native form to `Ag^(+)`
B. to oxidise lead and zinc impurities
C. to form a complec with `Ag^(+)` which is then reduced to metallic silver by using zinc
D. to oxidise the sulphur in the argentite ore to `SO_(2)` which escapes from the reaction

Answer

B