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Roasting, calcination and reduction

55 questions on Roasting, calcination and reduction 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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Roasting zinc blende, ZnS, in a plentiful supply of air gives which solid product? NEET level
Strong heating of limestone in the absence of air, a calcination, evolves which gas? NEET level
The correct formula of the iron ore magnetite is NEET level
In the blast furnace, which substance is added to combine with silica gangue and form a fusible slag? NEET level
Which gas is liberated when galena, PbS, is roasted in air? NEET level
In the cooler, upper part of the blast furnace, iron oxides are mainly reduced by NEET level
In the thermite process the metal used as the reducing agent is NEET level
The slag formed in the extraction of iron in the blast furnace is chiefly NEET level
Among the common commercial forms of iron, the one having the lowest carbon content is NEET level
Copper matte consists mainly of NEET level
Calcination is carried out NEET level
Assertion (A): Zinc carbonate is calcined in a large excess of air to get zinc oxide. Reason (R): On heating, a carbonate ore decomposes thermally to the oxide ... JEE Main level
Assertion (A): The Ellingham line for C + O2 -> CO2 is almost horizontal. Reason (R): In this reaction the number of moles of gas does not change, so Delta S de... JEE Main level
Match List I with List II. List I: (1) Roasting (2) Calcination (3) Smelting with carbon (4) Aluminothermy. List II: (P) CaCO3 -> CaO + CO2 (Q) 2ZnS + 3O2 -> 2Z... JEE Main level
Match List I with List II. List I (compound): (1) HgS (2) PbS (3) ZnCO3 (4) Fe2O3. List II (treatment): (P) calcined, then the oxide is reduced with coke near 1... JEE Main level
The negative slope of the Ellingham line for 2C + O2 -> 2CO arises because JEE Main level
Sulphide ores are generally roasted to oxides before reduction with carbon mainly because JEE Main level
In the self-reduction 2Cu2O + Cu2S -> 6Cu + SO2, the reducing agent is JEE Main level
Which reaction in the blast furnace regenerates the reducing gas CO from CO2? JEE Main level
In the reduction ZnO + C -> Zn + CO carried out near 1673 K, zinc is obtained as vapour that is condensed, because JEE Main level
Chromium(III) oxide is reduced by aluminium rather than by carbon in the metallurgy of chromium. Which Ellingham-based statement supports aluminium? JEE Main level
Which of the following, on simply heating in air, gives the metal directly through auto-reduction? JEE Main level
Pure dolomite, CaCO3.MgCO3 (Ca 40, Mg 24, C 12, O 16), is calcined completely to CaO and MgO. The percentage loss in mass of the solid is closest to JEE Main level
Iron pyrites is roasted: 4FeS2 + 11O2 -> 2Fe2O3 + 8SO2. The volume of O2 at STP consumed per mole of FeS2 roasted is JEE Main level
Which statement about slag in the blast furnace is correct? JEE Main level
In copper extraction, silica is added during smelting of roasted pyrites to remove iron(II) oxide. The flux, its nature and the slag formed are JEE Main level
In the puddling furnace used to make wrought iron from cast iron, the haematite lining serves as JEE Main level
In the self-reduction step in lead extraction from partly roasted galena, the number of moles of PbO that react with one mole of PbS is JEE Main level
Which operation is a calcination whose chief gaseous product is CO2? JEE Main level
Select the correct statements about calcination. JEE Main level
Complete heating of which of the following gives CO2 as one of the products? JEE Main level
Which of the following reductions are used industrially for the oxide named? JEE Main level
A haematite ore sample of mass 250 kg contains 76% Fe2O3 by mass, the rest being gangue. It is reduced by CO in a blast furnace according to Fe2O3 + 3CO -> 2Fe ... JEE Main level
At 1500 K the standard Gibbs energies of formation of oxides, per mole of O2 consumed, are (in kJ): 2Fe + O2 -> 2FeO, -380; 2Zn + O2 -> 2ZnO, -390; 2C + O2 -> 2... JEE Advanced level
Choose the correct statements about the Ellingham diagram for oxides (standard Gibbs energy per mole of O2 against temperature). JEE Advanced level
Select the correct statements about iron extraction in a blast furnace. JEE Advanced level
Which of the following thermite-type reductions are thermodynamically possible with the metal as reductant (Al lies below Cr, Fe and Cu on the Ellingham diagram... JEE Advanced level
In the conversion of copper matte in a Bessemer converter, the final stage is 2Cu2O + Cu2S -> 6Cu + SO2. Select the correct statements. JEE Advanced level
Select the correct statements about roasting of sulphide ores. JEE Advanced level
A 194 g sample of pure ZnS (Zn 65, S 32, O 16) is completely roasted: 2ZnS + 3O2 -> 2ZnO + 2SO2. Select the correct statements (STP molar volume 22.4 L/mol). JEE Advanced level
Select the correct statements about the extraction of zinc from zinc blende. JEE Advanced level
For the oxide formations per mole of O2 (in kJ, T in K): 2Zn + O2 -> 2ZnO, Delta G deg = -690 + 0.198 T; 2C + O2 -> 2CO, Delta G deg = -222 - 0.1752 T. Treating... JEE Advanced level
The standard Gibbs energy changes (per mole of O2, in kJ) are 2M + O2 -> 2MO: -610 + 0.19 T, and 2C + O2 -> 2CO: -225 - 0.17 T. Carbon begins to reduce MO above... JEE Advanced level
An ore X, heated in excess of air, gives a colourless pungent gas Y that turns acidified K2Cr2O7 paper green, and a solid Z. Z is reduced by carbon only near 16... JEE Advanced level
Copper(I) sulphide is converted to copper in two stages: 2Cu2S + 3O2 -> 2Cu2O + 2SO2, then 2Cu2O + Cu2S -> 6Cu + SO2 (no further air). Taking all the Cu2S throu... JEE Advanced level
Lead is obtained from impure galena by partial roasting (2PbS + 3O2 -> 2PbO + 2SO2) followed by self-reduction (PbS + 2PbO -> 3Pb + SO2). Assume all lead of the... JEE Advanced level
Assertion (A): Carbon cannot reduce MgO to magnesium at 1500 K. Reason (R): At 1500 K the Ellingham line of 2Mg + O2 -> 2MgO lies below that of 2C + O2 -> 2CO, ... JEE Advanced level
At 1200 K the standard Gibbs energies (per mole of O2, in kJ) are: 2C + O2 -> 2CO, -440; 2CO + O2 -> 2CO2, -360; and for the oxides of four metals formed as 2M ... JEE Advanced level
A 1000 kg ore charge contains 60% Fe2O3, 20% Fe3O4 and 20% SiO2 by mass (Fe 56, O 16, Si 28, Ca 40, C 12). All iron oxides are reduced to iron, and the silica i... JEE Advanced level
For oxide formation (per mole of O2, in kJ, T in K): 2M + O2 -> 2MO, Delta G deg=-560+0.20 T; 2C + O2 -> 2CO, Delta G deg=-225-0.175 T. The Delta G deg of MO + ... JEE Advanced level
Assertion (A): For an ore containing silica as gangue, calcium oxide is used as the flux in smelting. Reason (R): CaO is an acidic oxide and therefore combines ... JEE Advanced level
In a thermite reaction Fe2O3 + 2Al -> Al2O3 + 2Fe, the standard enthalpies of formation are Delta_fH deg(Al2O3)=-1676 and Delta_fH deg(Fe2O3)=-824 kJ/mol. The h... JEE Advanced level
In the blast furnace, C + CO2 -> 2CO and Fe2O3 + 3CO -> 2Fe + 3CO2 operate in a cycle, so that the carbon is consumed only in the net change 2Fe2O3 + 3C -> 4Fe ... JEE Advanced level
Six moles of PbS are roasted so that exactly half is converted to PbSO4 (PbS + 2O2 -> PbSO4) and the rest is left unchanged. Air is then cut off and the mixture... JEE Advanced level
At 1200 K, per mole of O2, Delta G deg values (in kJ) are -880 for frac43Al + O2 -> (2)/(3)Al2O3 and -640 for frac43Cr + O2 -> (2)/(3)Cr2O3. If aluminothermy is... JEE Advanced level