Question

Which of the following statements is/are true?

• A. In process of the precipitation of silver from sodium dicyano argentate (I), the zinc acts as reducing agent as well as complexing agent.
• B. In the process of roasting, the copper pyrites is converted into a mixture of $C{u}_{2}S$ & FeS which, in turn, are partially oxidised.
• C. Limonite, haematite and magnesite are ores of iron.
• D. Tin and lead both are extracted from their ores by carbon reduction.

Answer 1

Answer: (A), (B), (D)

The correct options are
A In process of the precipitation of silver from sodium dicyano argentate (I), the zinc acts as reducing agent as well as complexing agent.
B In the process of roasting, the copper pyrites is converted into a mixture of $C{u}_{2}S$ & FeS which, in turn, are partially oxidised.
D Tin and lead both are extracted from their ores by carbon reduction.

$Ag\to \left[A{g}^{+}\right]$ this is a oxidation process, which then form complex with $C{N}^{-}$.
$2\left[Ag\right(CN{)}_2]+Zn\to 2Ag\downarrow +[Zn(CN{)}_4{]}^{2-}$. Zinc acts both as complexing and reducing reagent.
In the process of roasting, the copper pyrites is converted into a mixture of $C{u}_{2}S$ & FeS which, in turn, are partially oxidised.
As roasting is generally used to convert sulphide ore into oxide.
Magnesite $\left(MgC{O}_3\right)$ is ore of magnesium.
Carbon reduction:
$Sn{O}_2+2C\to Sn+2CO$,
$2PbS+3O_2\to 2PbO+S{O}_3$
$PbO+C\to Pb+CO$.