Question

Assertion :Extraction of gold from its native ore involves leaching the metal ore with dilute solution of NaCN in presence of air. Reason: This is an oxidation reaction and leads to the formation of a soluble complex.

• 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 A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

In extraction of gold: $4Au+8C{N}^{-}+2H_{2}O+O_2\left(air\right)\to 4\left[Au\right(CN{)}_2{]}^{-}+4O{H}^{-}$.
Where, $Au\left(s\right)\stackrel{O_2}{\to }A{u}^{+}(aq.)$ and $A{u}^{+}+2C{N}^{-}(aq.)\to \left[Au\right(CN{)}_2{]}^{-}$ soluble complex formed, so both Assertion and Reason are correct.