The process of bringing the metal ore into solution by the action of a suitable chemical reagent followed by extraction of the metal either by electrolysis or by a suitable precipitating agent is called-
1. Electrometallurgy
2. Hydrometallurgy
3. Electrorefining
4. Zone refining

Consider the following metallurgical process:

Sulphide  \(\xrightarrow[]{\Delta }\)  oxide  \(\xrightarrow[]{\Delta }\)
Impure metal \(\xrightarrow[]{\Delta }\) pure metal

The processes A, B, and C in the above mentioned reaction are, respectively:

1. Calcination, smelting, and electrolysis

2. Roasting, smelting, and electrolysis

3. Calcination, auto reduction, and bessemerisation

4. Roasting, aluminothermic reduction, electrolysis

Consider the following reaction.
\(\small{Bauxite\ ore\ +\ NaOH\ (conc.) \xrightarrow[\Delta]{Digester} \underset{Soluble}{(A)}}\)
\((A) \xrightarrow{Fresh\ Al(OH)_3}\ \underset{White}{(B)}\ +\ (C)\)
\({(B)} \xrightarrow[]{\Delta}\ (D)\ +\ H_2O\)
What is the molecular formula of compound D?

1. ${\mathrm{NaAlO}}_2$

2. $\mathrm{Al}{\left(\mathrm{OH}\right)}_3$

3. ${\mathrm{Al}}_2{\mathrm{O}}_3$

4. ${\mathrm{Na}}_2\mathrm{O}$

2MS + 3O₂ → 2MO + 2SO₂
2MO + MS → 3M + SO₂

The metal M in above-mentioned reaction is:

1. Mg

2. Pb

3. Sn

4. Fe

Among the following a non-oxide ore is:

1. Malachite

2. Cuprite

3. Zincite

4. Bauxite

Which of the following is an incorrect match?

1. Kaolinite - Al₂(OH)₄Si₂O₅

2. Cuprite - Cu₂O

3. Siderite - FeCO₃

4. Calamine - ZnSO₄

The substance that acts as a collector in the froth flotation method is:

1. Sodium xenate.           

2. Sodium pyrophosphate.

3. Sodium nitroprusside.

4. Sodium ethyl xanthate. 

The extraction of gold and silver involves leaching with CN^- ion. Silver is later recovered by:

1. Liquation

2. Distillation

3. Zone refining

4. Displacement with Zn

4M + 8CN^- + 2H₂O + O₂$\to$ 4[M(CN)₂]^- + 4OH^-

2[M(CN)₂]^- + Zn$\to$[Zn(CN)₄]^2- + 2M

The metal M in above-mentioned reaction is:

1. Nickel

2. Silver

3. Copper

4. Mercury

Why is roasting important in the iron metallurgy process?