A major impurity in pig iron is:

1. Carbon

2. Silicon

3. Phosphorus

4. Manganese

Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?

1. Carbon and hydrogen suitable reducing agents for metal sulphides

2. The ${∆}_f{G}^0$ of the sulphide is greater than those for $C{S}_2$ and $H_{2}S$

3. the ${∆}_f{G}^0$ is negative for roasting of sulphur ore to oxide.

4. Roasting of the sulphide to the oxide is thermodynamically feasible

Sulphide ores of metals are usually concentrated by froth flotation process. Which one of the following sulphide ores offers an exception and is concentrated by chemical leaching?

1. Argentite

2. Galena

3. Copper pyrite

4. Sphalerite

Identify the incorrect statement

In the conversion of Zinc ore to zinc metal, the process of roasting involves

1.  ${\mathrm{ZnCO}}_3 \stackrel{}{\to } \mathrm{ZnO}$

2.  $\mathrm{ZnO} \stackrel{}{\to } {\mathrm{ZnSO}}_4$

3.  $\mathrm{ZnS} \stackrel{}{\to } \mathrm{ZnO}$

4.  $\mathrm{ZnS} \stackrel{}{\to } {\mathrm{ZnSO}}_4$

The extraction of silver is achieved by the initial complexation of the ore (Argentine) with X followed by reduction with Y. X and Y respectively are 

1.  ${\mathrm{CN}}^{-}$ and Zn

2.  ${\mathrm{CN}}^{-}$ and Cu

3.  ${\mathrm{Cl}}^{-}$ and Zn

4.  ${\mathrm{Br}}^{-}$ and Zn

Van Arkel method of purification of metals involves converting the metal to a

1. Volatile compound

2. Volatile unstable compound

3. Non-volatile stable compound

4. Non-volatile unstable compound

Which of the following is correct?

I.  $∆$G$°$ for reaction (i) is more negative at T < 1125K

II.  $∆$G$°$ for the reduction of CO is more negative at T < 1125K

III.  ${\mathrm{H}}_2$ is a better reducing agent at T < 1125K

IV.  ${\mathrm{H}}_2$ is a better reducing agent at T > 1125K

1.  I and II

2.  I and III

3.  III only

4.  I and IV

Which of the following reactions is an example of auto reduction?

1.  ${\mathrm{Fe}}_3{\mathrm{O}}_4 + 4\mathrm{CO} \stackrel{}{\to } 3\mathrm{Fe} + 4{\mathrm{CO}}_2$

2.  ${\mathrm{Cu}}_2\mathrm{O} + \mathrm{C} \stackrel{}{\to } 2\mathrm{Cu} + \mathrm{CO}$

3.  ${\mathrm{Cu}}^{2+} \left(\mathrm{aq}\right) + \mathrm{Fe} \left(\mathrm{s}\right) \stackrel{}{\to } \mathrm{Cu} \left(\mathrm{s}\right) + {\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right)$

4.  ${\mathrm{Cu}}_2\mathrm{O} + \frac{1}{2} {\mathrm{Cu}}_2\mathrm{S} \stackrel{}{\to } 3\mathrm{Cu} + \frac{1}{2} {\mathrm{SO}}_2$

A number of elements are available in earth’s crust but most abundant elements are ____________.

1.  Al and Fe

2.  Al and Cu

3.  Fe and Cu

4.  Cu and Ag