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10
MCQ (Single Correct Answer)

Extraction of gold and silver involves leaching the metal with $\mathrm{CN}^{-}$ion The metal is recovered by ........... .

A
displacement of metal by some other metal from the complex ion.
B
roasting of metal complex.
C
calcination followed by roasting.
D
thermal decomposition of metal complex.
11
MCQ (Single Correct Answer)

Choose the correct option of temperature at which carbon reduces Fe 0 to iron and produces CO.

A
Below temperature at point $A$
B
Approximately at the temperature corresponding to point $A$
C
Above temperature at point $A$ but below temperature at point $D$
D
Above temperature at point $A$
12
MCQ (Single Correct Answer)

Below point 'A' Fe0 can ............ .

A
be reduced by carbon monoxide only.
B
be reduced by both carbon monoxide and carbon.
C
be reduced by carbon only.
D
not be reduced by both carbon and carbon monoxide.
13
MCQ (Single Correct Answer)

For the reduction of FeO at the temperature corresponding to point D , which of the following statements is correct?

A
$\Delta G$ value for the overall reduction reaction with carbon monoxide is zero.
B
$\Delta G$ value for the overall reduction reaction with a mixture of 1 mol carbon and 1 mol oxygen is positive.
C
$\Delta G$ value for the overall reduction reaction with a mixture of 2 mol carbon and 1 mol oxygen will be positive.
D
$\Delta G$ value for the overall reduction reaction with carbon monoxide is negative.
14
MCQ (Multiple Correct Answer)

At the temperature corresponding to which of the points in Fig. FeO will be reduced to Fe by coupling the reaction $2 \mathrm{FeO} \longrightarrow \mathrm{WFe}+\mathrm{O}_2$ with all of the following reactions?

$$\text { 1. } \mathrm{C}+\mathrm{O} \longrightarrow \mathrm{CO}_2$$

$$\begin{aligned} & \text { 2. } 2 \mathrm{C}+\mathrm{O}_2 \longrightarrow 2 \mathrm{CO} \\ & \text { 3. } 2 \mathrm{CO}+\mathrm{O}_2 \longrightarrow 2 \mathrm{CO}_2 \end{aligned}$$

A
Point $A$
B
Point $B$
C
Point $D$
D
Point $E$
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