Carbon cannot be used in the reduction of ${\mathrm{Al}}_2{\mathrm{O}}_3$ because

(I)  It is non-metal

(2)  The heat of the formation of ${\mathrm{CO}}_2$ is more than that of ${\mathrm{Al}}_2{\mathrm{O}}_3$

(3)  Pure carbon is not easily available

(4)  The heat of formation of ${\mathrm{Al}}_2{\mathrm{O}}_3$ is too high

Which of the following statements is correct regarding the slag obtained during the extraction of a metal like copper or iron?

(1)  The slag is lighter and has a lower melting point than the metal

(2)  The slag is heavier and has a lower melting point than the metal

(3)  The slag is lighter and has a higher melting point than the metal

(4)  The slag is heavier and has a higher melting point than the metal

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

Assertion : Sodium chloride is added during electrolysis of fused anhydrous magnesium
chloride.

Reason : Anhydrous magnesium chloride is obtained by heating hydrated magnesium
chloride, $MgC{l}_2.6H_{2}O$.

Ellingham diagram for the formation of ${\mathrm{CO}}_2$ is a straight line in the given graph. This is due to

1.  Increase in entropy during ${\mathrm{CO}}_2$ formation

2.  Decrease in entropy during ${\mathrm{CO}}_2$ formation

3.  Entropy remains constant during ${\mathrm{CO}}_2$ formation

4.  Cannot be predicted

The depressant NaCN

1. Used to separate PbS from ZnS by forming a complex with PbS

2. Used to separate PbS from ZnS by forming a complex with ZnS

3. Used to form froth

3. Used as the collector

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

Silver containing lead as an impurity is removed by

1.  Poling

2.  Cupellation

3.  Lavigation

4.  Distillation

When an impurity in metal has a greater affinity for oxygen and is more easily oxidized than the metal itself, then the metal is refined by

(1)  Cupellation

(2)  Zone refining

(3)  Poling

(4)  Electrorefining

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. ${\mathrm{Na}}_2\mathrm{O}$