Bauxite ore is concentrated by ____.

Which of the following reagent is used in leaching of gold?

In the equation, $4\mathrm{M}+ 8{\mathrm{CN}}^{\mathrm{-}}+ 2{\mathrm{H}}_{\mathrm{2}}\mathrm{O}+{\mathrm{O}}_{\mathrm{2}}\mathrm{ }\to \mathrm{4[}\mathrm{M}(\mathrm{CN}{)}_{\mathrm{2}}{\mathrm{]}}^{\mathrm{-}}+ 4{\mathrm{OH}}^{\mathrm{-}}$, the metal $\mathrm{M}$ is ______.

Extraction of gold and silver involves leaching with ${\mathrm{CN}}^{-}$ ion. Silver is later recovered by:

When limestone is heated, ${\mathrm{CO}}_{\mathrm{2}}$ is given off. The metallurgical operation is ____.

The substance which is mixed with the ore for removal of impurities is termed as _____.

Flux is used to remove_____.

Which of the following flux is used to remove acidic impurities in metallurgical process?