Question

Assertion :In cyanide process for the extraction of gold and silver from their native ores, the cyanide solution acts as a reducing agent to reduce the gold and silver compounds present in the ores into the metallic states. Reason: In the extraction of gold and silver, the cyanide solution acts as complexing reagent in the presence of air and form their respective soluble complexes.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is D Assertion is incorrect but Reason is correct

In extraction of silver - $A{g}_{2}S+4NaCN\to 2Na\left[Ag\right(CN{)}_2]+N{a}_{2}S$

And in extraction of gold - $4Au+8NaCN+2H_{2}O+O_2\to 4Na\left[Au\right(CN{)}_2]+4NaOH$

It is clear from the equation that $C{N}^{-}$ does not act as a reducing agent.

But from these equations, it is clear that in the extraction of gold and silver, the cyanide solution acts as a complexing reagent in the presence of air and form their respective soluble complexes.

Option D is correct.