The process of converting hydrated alumina into anhydrous alumina is called

(1)  Roasting

(2)  Smelting

(3)  Dressing

(4)  Calcination

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

The metal M in above-mentioned reaction is:

1. Mg

2. Pb

3. Sn

4. Fe

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. ${\mathrm{Na}}_2\mathrm{O}$

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

Silver containing lead as an impurity is removed by

1.  Poling

2.  Cupellation

3.  Lavigation

4.  Distillation

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

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

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

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