General Principles and Processes of Isolation of Metals JEE Advanced previous year questions with solutions

5 solved JEE Advanced questions on General Principles and Processes of Isolation of Metals, free to read — no sign-in needed. The full chapter has 23 questions; sign in to attempt the remaining 18 in the exam simulator.

1. Q1JEE Advanced Adv 2023 (Paper 1)
   The correct statement(s) related to processes involved in the extraction of metals is(are)
   1. A.Roasting of Malachite produces Cuprite
   2. B.Calcination of Calamine produces Zincite
   3. C.Copper pyrites is heated with silica in a reverberatory furnace to remove iron
   4. D.Impure silver is treated with aqueous $KCN$ in the presence of oxygen followed by reduction with zinc metal
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   Answer: B,C,D

   The ore Calamine contain ${ZnCO}_{3}$. The Calamine on heating produces $ZnO$.${ZnCO}_{3}\rightarrow ^{∆}ZnO+{CO}_{2}$ Cyanide process, also called Macarthur-forrest Process, method of extracting silver from impure ores by dissolving them in a dilute solution of sodium cyanide in the presence of oxygen. The complex formed in the above process reduced to silver metal by the treatment with zinc. ${O}_{2}+{H}_{2}O+Ag+NaCN\rightarrow ^{}Na\left[Ag{\left(CN\right)}_{2}\right]+NaOH Na\left[Ag{\left(CN\right)}_{2}\right]\rightarrow ^{Zn}{Na}_{2}\left[Zn{\left(CN\right)}_{4}\right]+Ag$ ${SiO}_{2}$​ (Silica) is a flux material. It removes impurities as slag. Here, slag consists of Iron in Sulphide ore of $Cu$, here impurity is $FeO$. $FeO+{SiO}_{2}\rightarrow ^{}{FeSiO}_{3}$ Malachite green is ${CuCO}_{3}.Cu{\left(OH\right)}_{2}$ and cuprite is ${Cu}_{2}O$. The ore malachite green on heating gives cupric oxide but not cuprous oxide. ${CuCO}_{3}.Cu{\left(OH\right)}_{2}\rightarrow ^{∆}2CuO+{CO}_{2}+{H}_{2}O$
2. Q2JEE Advanced Adv 2022 (Paper 2)
   The correct option(s) related to the extraction of iron from its ore in the blast furnace operating in the temperature range $900-1500K$ is(are)
   1. A.Limestone is used to remove silicate impurity.
   2. B.Pig iron obtained from blast furnace contains about $4$ carbon.
   3. C.Coke $\left(C\right)$converts ${CO}_{2}$ to $CO$.
   4. D.Exhaust gases consist of ${NO}_{2}$ and $CO$.
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   Answer: A,B,C

   (A) Limestone is added to remove silica as impurity. $CaO+{SiO}_{2}\rightarrow {CaSiO}_{3}(inthetemperaturerange900–1500K)$ (B) Pig iron obtained from blast furnace contains $4$ carbon and many other impurities (eg. $S,P,Si,Mn$) in small amount. In fusion zone molten iron becomes heavy by absorbing elemental impurities and produces Pig iron. (in the temperature range 900 – 1500 K) (C) Coke $\left(C\right)$ converts ${CO}_{2}$ in $CO$. $C+{CO}_{2}\rightarrow 2CO$ (D) Exhaust gases consist of $CO$ and ${CO}_{2}$. Exhaust gases does not contain NO2 Hence, (A,B,C) are correct.
3. Q3JEE Advanced Adv 2022 (Paper 1)
   The electrochemical extraction of aluminium from bauxite ore involves
   1. A.the reaction of ${Al}_{2}{O}_{3}$ with coke $\left(C\right)$ at a temperature $\gt 2500^{\circ}C$.
   2. B.the neutralization of aluminate solution by passing ${CO}_{2}$ gas to precipitate hydrated alumina $\left({Al}_{2}{O}_{3}.3{H}_{2}O\right)$.
   3. C.the dissolution of ${Al}_{2}{O}_{3}$ in hot aqueous $NaOH$.
   4. D.the electrolysis of ${Al}_{2}{O}_{3}$ mixed with ${Na}_{3}{AlF}_{6}$ to give $Al$ and ${CO}_{2}$.
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   Answer: B,C,D

   (A) The reduction of ${Al}_{2}{O}_{3}$ with coke $\left(C\right)$ at a temperature $\gt 2500^{\circ}C$ is not carried out due to the formation of carbides. (B) It is correct as neutralisation of aluminate solution is done by passing ${CO}_{2}$ gas to precipitate hydrated alumina. (C) Reaction of powdered one is carried out with hot concentrated $NaOH$ at $473K-523K$ and $35-36$ bar pressure. (D)Aluminium In the metallurgy of aluminium, purified Al2O3 is mixed with ${Na}_{3}{AlF}_{6}$ or CaF2 which lowers the melting point of the mixture and brings conductivity.Thus electrolysis of the molten mass is carried out in an electrolytic cell using carbon electrodes. The oxygen liberated at anode reacts with the carbon of anode producing CO and CO2 and Al at the cathode.
4. Q4JEE Advanced Adv 2021 (Paper 1)
   The correct statement $\left(s\right)$ related to the metal extraction processes is(are)
   1. A.A mixture of $PbS$ and $PbO$ undergoes self-reduction to produce $Pb$ and ${SO}_{2}.$
   2. B.In the extraction process of copper from copper pyrites, silica is added to produce copper silicate.
   3. C.Partial oxidation of sulphide ore of copper by roasting, followed by self-reduction produces blister copper.
   4. D.In cyanide process, zinc powder is utilized to precipitate gold from $Na\left[Au{\left(CN\right)}_{2}\right].$
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   Answer: A,C,D

   $\left(A\right)$ $PbS+PbO\rightarrow Pb+{SO}_{2}$It is self-reduction reaction. $\left(B\right)$ In the extraction process of copper from copper pyrites, silica is added to produce Iron silicate. $\left(C\right)$ Partial oxidation of sulphide ore of copper by roasting, followed by self-reduction produces blister copper. ${Cu}_{2}S+{O}_{2}\rightarrow _{}{Cu}_{2}O+{SO}_{2}$ ${Cu}_{2}S+2{Cu}_{2}O\rightarrow _{self-reduction}6Cu+{SO}_{2}$ $\left(D\right)$ $Zn+2Na\left[Au{\left(CN\right)}_{2}\right]\rightarrow {Na}_{2}\left[Zn{\left(CN\right)}_{4}\right]+2Au$
5. Q5JEE Advanced Adv 2020 (Paper 2)
   Which among the following statement(s) is (are) true for the extraction of aluminium from bauxite?
   1. A.Hydrated ${Al}_{2}{O}_{3}$ precipitates, when ${CO}_{2}$ is bubbled through a solution of sodium aluminate.
   2. B.Addition of ${Na}_{3}{AlF}_{6}$ lowers the melting point of alumina.
   3. C.${CO}_{2}$ is evolved at the anode during electrolysis.
   4. D.The cathode is a steel vessel with a lining of carbon.
   Show answer & solution

   Answer: A,B,C,D

   (A) $2{NaAlO}_{2}+3{H}_{2}O+{CO}_{2}⟶2Al(OH{)}_{3}+{Na}_{2}{CO}_{3}$ (B) In Hall-Heroult process ${Na}_{3}Al/{F}_{6}$ and ${CaF}_{2}$ is mixed with ${Al}_{2}{O}_{3}$ to lower melting point and increase conductivity. (C) $Anode\text{C}(\text{s})+2{\text{O}}^{2-}(\text{melt})\rightarrow {\text{CO}}_{2}(\text{g})+4{\text{e}}^{-}$ (D) Steel cathode with carbon lining and graphite anode are used.