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Extraction of Fe, Cu, Zn, Al, Ag, Au

55 questions on Extraction of Fe, Cu, Zn, Al, Ag, Au from the Metallurgy chapter: 11 NEET level, 22 JEE Main, 22 JEE Advanced. Each one opens with its answer and solution.

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Which of the following is the formula of haematite, the chief ore of iron? NEET level
Zinc blende, an important ore of zinc, is chemically NEET level
Chalcopyrite (copper pyrites), the most important ore of copper, has the formula NEET level
Froth flotation is mainly employed for the concentration of NEET level
Cryolite, Na3AlF6, is added to alumina in the Hall-Heroult cell mainly to NEET level
In the cyanide process, native silver is leached with dilute aqueous NaCN in the presence of air. The soluble silver species formed is NEET level
The slag formed in the blast furnace during the extraction of iron is mainly NEET level
Bauxite, the main ore of aluminium, is represented by the formula NEET level
After leaching a gold ore with aqueous NaCN and air, gold is recovered from the solution of Na[Au(CN)2] by adding NEET level
Roasting zinc blende in excess air gives NEET level
Blister copper has a blistered surface because NEET level
In the Baeyer process, bauxite is digested with concentrated NaOH at about 500 K under pressure. The undissolved residue (red mud) is mainly JEE Main level
Assertion (A): No external carbon is needed to obtain copper from Cu2S in the Bessemer converter. Reason (R): Part of the Cu2S is oxidised to Cu2O, which then r... JEE Main level
In Hall's process, bauxite rich in iron oxide is fused with Na2CO3 to give soluble NaAlO2. Aluminium hydroxide is then precipitated from the aqueous extract by ... JEE Main level
In the Serpeck process, silica-rich bauxite is heated with coke in a stream of nitrogen at about 1800 K. The aluminium compound formed, which is then hydrolysed... JEE Main level
Match the metal in List I with the key extraction step in List II. List I: P. Fe Q. Cu R. Zn S. Al List II: 1. electrolysis of alumina dissolved in molten cryol... JEE Main level
Which reaction supplies most of the heat in the blast furnace and takes place in the hottest region near the air blast? JEE Main level
The graphite anodes of a Hall-Heroult cell must be replaced from time to time because JEE Main level
In the reduction of ZnO with coke at about 1673 K, zinc (boiling point 1180 K) leaves the retort as JEE Main level
Assertion (A): During the cyanide leaching of gold, air is bubbled through the mixture. Reason (R): Oxygen oxidises gold to Au(I), which is stabilised as [Au(CN... JEE Main level
Blister copper containing dissolved cuprous oxide is stirred with green logs of wood (poling). The purpose is to JEE Main level
During the electrolytic refining of copper using acidified CuSO4 electrolyte with an impure copper anode, the metals that collect as anode mud are JEE Main level
When argentite, Ag2S, is leached with aqueous NaCN it forms Na[Ag(CN)2] and Na2S. Air is blown through the mixture mainly to JEE Main level
Which of the following changes is a calcination? JEE Main level
A mixture of PbS and ZnS is subjected to froth flotation. Sodium cyanide is added so that JEE Main level
In an Ellingham diagram the line for 2C + O2 -> 2CO slopes downwards while the lines for most metal oxides slope upwards. The reason is that JEE Main level
During smelting of roasted chalcopyrite with silica in a reverberatory furnace, iron is removed as JEE Main level
In converting cast iron into wrought iron in a reverberatory (puddling) furnace, the furnace is lined with JEE Main level
A sample of 2.40 kg of iron ore contains 64.0% Fe2O3 by mass. Reduction in a blast furnace recovers 90.0% of the iron present. Taking Fe = 56 and O = 16, calcul... JEE Main level
Select all the sulphide ores from the following. JEE Main level
In the froth flotation of a sulphide ore, which of the following statements are correct? JEE Main level
Which statements about the purification of bauxite by the Baeyer process are correct? JEE Main level
For the electrolytic refining of copper with acidified CuSO4 electrolyte, select the correct statements. JEE Main level
Chalcopyrite is roasted so that its iron is converted to FeO (the first step being 2CuFeS2 + O2 -> Cu2S + 2FeS + SO2 followed by 2FeS + 3O2 -> 2FeO + 2SO2), and... JEE Advanced level
At 1500 K the standard Gibbs energies of formation of oxides per mole of O2 are: 4/3 Al + O2 -> 2/3 Al2O3, -820 kJ; 2Fe + O2 -> 2FeO, -380 kJ. Using these data,... JEE Advanced level
For 2Zn + O2 -> 2ZnO, Delta H deg=-700 kJ and Delta S deg=-0.200 kJ K^-1; for 2C + O2 -> 2CO, Delta H deg=-221 kJ and Delta S deg=+0.180 kJ K^-1 (both per mole ... JEE Advanced level
Gold is leached by 4Au + 8NaCN + O2 + 2H2O -> 4Na[Au(CN)2] + 4NaOH and recovered by 2Na[Au(CN)2] + Zn -> Na2[Zn(CN)4] + 2Au. For 4.925 g of gold (Au = 197, Zn =... JEE Advanced level
A 2.00 kg sample of bauxite contains 51.0% Al2O3 (the rest is inert to the reagents). It is digested with excess NaOH by Al2O3 + 2NaOH + 3H2O -> 2Na[Al(OH)4] an... JEE Advanced level
An impure copper anode contains Zn, Fe, Ag and Au. Standard reduction potentials (V): Zn^2+/Zn -0.76, Fe^2+/Fe -0.44, Cu^2+/Cu +0.34, Ag+/Ag +0.80, Au^3+/Au +1.... JEE Advanced level
Assertion (A): Aluminium cannot be extracted by electrolysing an aqueous solution of aluminium sulphate. Reason (R): Al^3+ is reduced at the cathode in preferen... JEE Advanced level
A metal M occurs as a sulphide ore concentrated by froth flotation. The ore is roasted, the oxide is heated with coke near 1673 K and M leaves the furnace as va... JEE Advanced level
Argentite (Ag2S, molar mass 248) is treated as follows: Ag2S + 4NaCN -> 2Na[Ag(CN)2] + Na2S; the sulphide is oxidised by 2Na2S + 2O2 + H2O -> Na2S2O3 + 2NaOH; t... JEE Advanced level
In a Bessemer converter, 477 g of pure Cu2S (Cu = 63.5, S = 32) is converted into copper by the sequence 2Cu2S + 3O2 -> 2Cu2O + 2SO2 and Cu2S + 2Cu2O -> 6Cu + S... JEE Advanced level
A blast-furnace charge of 1000 kg ore contains 18.0% SiO2 as the only acidic gangue. It is fluxed with limestone which is 90.0% CaCO3 by mass (the rest is inert... JEE Advanced level
Pig iron (8.00 kg) with 4.20% carbon is converted to wrought iron containing 0.20% carbon, taken here to mean that 4.00% of the original mass is removed as carb... JEE Advanced level
Iron is produced from Fe2O3 by aluminothermy, 2Al + Fe2O3 -> Al2O3 + 2Fe. To obtain 2.24 kg of iron (Fe = 56, Al = 27, O = 16), the masses of aluminium consumed... JEE Advanced level
Copper is refined electrolytically in acidified CuSO4 using an anode that is 80.0% Cu, 15.0% Zn and 5.0% Ag by mass. A steady current of 19.3 A passes for 5000 ... JEE Advanced level
A Hall-Heroult cell is run at a steady current of 40.0 kA for 6.00 hours with a current efficiency of 88.0% (only this fraction of the charge deposits aluminium... JEE Advanced level
Which statements about the blast furnace extraction of iron are correct? JEE Advanced level
Which statements about extraction of copper from chalcopyrite are correct? JEE Advanced level
Which statements about the Hall-Heroult process are correct? JEE Advanced level
Which statements about extraction of silver by the cyanide process are correct? JEE Advanced level
Which statements about the extraction of zinc are correct? JEE Advanced level
At 1500 K, standard Gibbs energies of oxide formation per mole of O2 are: 2C + O2 -> 2CO -440 kJ; 2Fe + O2 -> 2FeO -380 kJ; 2Zn + O2 -> 2ZnO -300 kJ; 4/3 Al + O... JEE Advanced level
Which statements about refining of metals are correct? JEE Advanced level