Roasting of sulphides gives the gas 'X' as a by-product. This is a colourless gas with the choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic, acts as an oxidising agent, and its acid has never been isolated. The gas 'X' is:

1. SO₂

2. CO₂

3. SO₃

4. H₂S

The correct statement among the following is:

A major impurity in pig iron is:

1. Carbon

2. Silicon

3. Phosphorus

4. Manganese

Among the following an iron mineral is:

1. Malachite

2. Cassiterite

3. Pyrolusite

4. Magnetite

An electrochemical process is used to extract:

1. Iron

2. Lead

3. Sodium

4. Silver

What method is used to extract zinc from zinc blende?

1. Electrolytic reduction

2. Roasting followed by reduction with carbon

3. Roasting followed by reduction with another metal

4. Roasting followed by self-reduction

Native silver metal forms a water-soluble complex with a dilute aqueous solution of NaCN in the presence of:

1. Nitrogen

2. Oxygen

3. Carbon Dioxide

4. Argon

Iron is extracted from chalcopyrite as :

1. FeO
2. FeS
3. Fe₂O₃
4. FeSiO₃

A metal's oxide that can be reduced by Fe as a reducing agent at a temperature $T_1$ is:

1. Zr

2. Ca

3. Mg

4. None of the above.

In the process of extraction of silver,

silver ore + ${\mathrm{CN}}^{-}+$ ${\mathrm{H}}_2\mathrm{O}\stackrel{{\mathrm{O}}_2}{\to }$ $$ $$ $$ $$ $$ $\left[\mathrm{X}\right]$ $+$ ${\mathrm{OH}}_{}^{-}$

[X] + Zn $\to$ $$[Y] + Ag

[X], and [Y] in the above mentioned reaction are:

1. X= [Ag(CN)${}_2$]^$-$; Y = [Zn(CN)${}_4$]^-2

2. X= [Ag(CN)${}_2$]^-3; Y=[Zn(CN)${}_4$]^-2

3. X= [Ag(CN)${}_2$]^$-$; Y=[Zn(CN)${}_6$]^$-$

4. X=[Ag(CN)${}_4$]^$-$ ; Y= [Zn(CN)${}_4$]^$-$2