Mix Examples of General Principles and processes of Isolation of Elements Questions in English

(A) The extraction of copper from copper pyrite involves the following steps:
$1$. Crushing and concentration of the ore by froth-flotation process.
$2$. Roasting of the concentrated ore to remove sulfur and convert iron into $FeO$,which is then removed as slag by adding silica $(SiO_2)$ as flux: $FeO + SiO_2 \rightarrow FeSiO_3$ (slag).
$3$. The roasted ore is smelted in a reverberatory furnace to obtain copper matte $(Cu_2S + FeS)$.
$4$. The matte is subjected to Bessemerization,where self-reduction occurs: $2Cu_2S + 3O_2 \rightarrow 2Cu_2O + 2SO_2$ and $2Cu_2O + Cu_2S \rightarrow 6Cu + SO_2$. This produces 'blister copper'.
$5$. Refining of blister copper is typically done by electrolytic refining,not by carbon reduction.
Therefore,steps $A, B,$ and $C$ are correct.

(B) Roasting of Malachite $(CuCO_3 \cdot Cu(OH)_2)$ produces $CuO$ (Tenorite),not Cuprite $(Cu_2O)$. Thus,$(A)$ is incorrect.
$(B)$ Calcination of Calamine $(ZnCO_3)$ produces Zincite $(ZnO)$: $ZnCO_3 \rightarrow ZnO + CO_2$. Thus,$(B)$ is correct.
$(C)$ Copper pyrites $(CuFeS_2)$ is heated with silica $(SiO_2)$ in a reverberatory furnace. $FeO$ reacts with $SiO_2$ to form $FeSiO_3$ (slag): $FeO + SiO_2 \rightarrow FeSiO_3$. Thus,$(C)$ is correct.
$(D)$ Impure silver is treated with aqueous $KCN$ in the presence of air $(O_2)$ to form a soluble complex,which is then reduced by $Zn$: $4Ag + 8CN^- + 2H_2O + O_2 \rightarrow 4[Ag(CN)_2]^- + 4OH^-$; $2[Ag(CN)_2]^- + Zn \rightarrow [Zn(CN)_4]^{2-} + 2Ag$. Thus,$(D)$ is correct.
Therefore,the correct statements are $(B)$,$(C)$,and $(D)$.

(B) . $2 Na[Al(OH)_4]_{(aq)} + CO_2 \longrightarrow Na_2CO_3 + H_2O + 2 Al(OH)_3(\downarrow)$. This is correct as hydrated alumina precipitates.
$B$. $Na_3AlF_6$ (cryolite) is added to lower the melting point of the mixture and increase conductivity. This is correct.
$C$. During electrolysis,carbon anodes react with oxygen to form $CO$ and $CO_2$. This is correct.
$D$. The electrolytic cell consists of a steel vessel with a carbon lining which acts as the cathode. This is correct.
Therefore,all statements $A, B, C,$ and $D$ are true.

(B) $PbS + 2PbO \rightarrow 3Pb + SO_2$ (self-reduction).
$(B)$ Silica $(SiO_2)$ is added to remove $FeO$ impurity as slag $FeSiO_3$,not copper silicate.
$(C)$ $CuFeS_2$ ore is partially oxidized by roasting,followed by self-reduction of $Cu_2S$ to produce blister copper.
$(D)$ In the cyanide process,zinc powder is used to precipitate gold from $Na[Au(CN)_2]$ via the reaction: $2Na[Au(CN)_2] + Zn \rightarrow Na_2[Zn(CN)_4] + 2Au$.

(A) Incorrect. The electrochemical extraction of aluminum (Hall-Heroult process) is performed at temperatures around $900-1000^{\circ} C$,not $>2500^{\circ} C$.
$(B)$ Correct. The sodium aluminate solution is neutralized by passing $CO_2$ gas to precipitate hydrated alumina: $2Na[Al(OH)_4]_{(aq)} + 2CO_{2(g)} \rightarrow Al_2O_3 \cdot 3H_2O_{(s)} \downarrow + 2NaHCO_{3(aq)}$.
$(C)$ Correct. Concentration of bauxite (Bayer's process) involves the dissolution of $Al_2O_3$ in hot aqueous $NaOH$: $Al_2O_3(s) + 2NaOH(aq) + 3H_2O(l) \rightarrow 2Na[Al(OH)_4](aq)$.
$(D)$ Correct. The electrolysis of $Al_2O_3$ is performed in a mixture with $Na_3AlF_6$ (cryolite) and $CaF_2$ to lower the melting point and increase conductivity,producing $Al$ at the cathode and $CO_2$ at the anode.

(C) Limestone $(CaCO_3)$ decomposes to $CaO$,which reacts with silica $(SiO_2)$ impurity to form calcium silicate $(CaSiO_3)$ slag: $CaO + SiO_2 \rightarrow CaSiO_3$. This is correct.
$(B)$ Pig iron is the iron obtained from the blast furnace,which contains about $4 \%$ carbon and many impurities like $S, P, Si, Mn$. This is correct.
$(C)$ In the hotter part of the furnace,coke reacts with $CO_2$ to produce $CO$: $C + CO_2 \rightarrow 2CO$. This is correct.
$(D)$ Exhaust gases consist mainly of $N_2$ and $CO$,not $NO_2$. This is incorrect.

(A) Bronze is an alloy of $Cu$ and $Sn$. $(A-IV)$
Brass is an alloy of $Cu$ and $Zn$. $(B-III)$
$UK$ silver coin is an alloy of $Cu$ and $Ni$. $(C-I)$
Stainless steel is an alloy of $Fe, Cr, Ni,$ and $C$. $(D-II)$
Therefore,the correct matching is $A-IV, B-III, C-I, D-II$.

(B) The chemical reaction for the fusion of chromite ore with sodium carbonate in the presence of oxygen is:
$4FeCr_2O_4 + 8Na_2CO_3 + 7O_2 \rightarrow 8Na_2CrO_4 + 2Fe_2O_3 + 8CO_2$
In this reaction,$Na_2CrO_4$ (sodium chromate) is water-soluble,while $Fe_2O_3$ (ferric oxide) is water-insoluble.
The molar mass of $Fe_2O_3$ is calculated as:
$M = (2 \times 56) + (3 \times 16) = 112 + 48 = 160 \ g \ mol^{-1}$.

(D) Brass is an alloy of copper $(Cu)$ and zinc $(Zn)$.
It does not contain iron $(Fe)$ as a primary component,making it a non-ferrous alloy.
Nickel steel,chromium steel,and stainless steel are all ferrous alloys as they contain iron.

(C) Titanium alloys are widely used in aerospace applications,particularly for ultra-high speed flight,because they maintain excellent mechanical properties and high strength-to-weight ratios at elevated temperatures.

(A) Brass is an alloy of copper $(Cu)$ and zinc $(Zn)$.
It does not contain iron $(Fe)$,therefore it is classified as a nonferrous alloy.

(A) Babbitt metal is a soft alloy primarily composed of tin.
It typically contains $89.3 \%$ tin,$7.1 \%$ antimony,and $3.6 \%$ copper.

(A) German silver is an alloy of copper $(Cu)$,zinc $(Zn)$,and nickel $(Ni)$ typically in the ratio of $2:1:1$.
It does not contain tin $(Sn)$.

(C) In the blast furnace process for the extraction of iron,the charge consists of roasted ore,coke,and limestone.
The approximate ratio of these components by mass is $12: 5: 3$.

(B) Bronze is an alloy primarily composed of copper $(Cu)$ and tin $(Sn)$. Therefore,the correct option is $B$.

(D) German silver is an alloy consisting of copper $(Cu)$,nickel $(Ni)$,and zinc $(Zn)$.
Its typical composition is approximately $50\%$ copper,$25\%$ nickel,and $25\%$ zinc.
Therefore,the correct option is $D$.

(A) The correct statement is that collectors enhance the non-wettability of mineral particles during froth flotation,not the wettability. Examples of collectors include pine oil,xanthates,and fatty acids. Therefore,option $A$ is incorrect.

(C) The composition of the given alloys is as follows:
$I$. Brass is an alloy of $Cu$ and $Zn$. (Incorrect)
$II$. Bronze is an alloy of $Cu$ and $Sn$. (Incorrect)
$III$. German silver is an alloy of $Cu$,$Zn$,and $Ni$. (Correct)
$IV$. Brass is an alloy of $Cu$ and $Zn$. (Correct)
Therefore,statements $III$ and $IV$ are correct.

(D) Duralumin is an alloy that primarily consists of $95 \% Al$,$3 \% Cu$,$0.5-1 \% Mg$,and $1-1.5 \% Mn$.
Therefore,the correct option is $D$.

(D) German silver is an alloy composed of Copper $(Cu)$,Zinc $(Zn)$,and Nickel $(Ni)$.
Brass is an alloy composed primarily of Copper $(Cu)$ and Zinc $(Zn)$.
Comparing the two,Copper $(Cu)$ and Zinc $(Zn)$ are common to both alloys.
Iron $(Fe)$ is not a primary component of either,but Nickel $(Ni)$ is present in German silver and is not a standard component of brass.
Therefore,the metal that is not common to both is Nickel $(Ni)$.
Hence,option $(D)$ is the correct answer.

(D) In the extraction of $Fe$ (iron),silica $(SiO_2)$ is added as a flux to remove $FeO$ impurity as iron silicate slag $(FeSiO_3)$.
In the extraction of $Cu$ (copper),$FeS$ present as an impurity is removed as iron silicate slag $(FeSiO_3)$ by adding $SiO_2$ flux.
In the extraction of $Zn$ (zinc),$FeO$ impurity is removed as iron silicate slag $(FeSiO_3)$ by adding $SiO_2$ flux.
Therefore,$Fe$,$Cu$,and $Zn$ involve the removal of impurities as slag.

(B) Copper matte is a molten mixture obtained during the extraction of copper from copper pyrites $(CuFeS_2)$.
It primarily consists of cuprous sulfide $(Cu_2S)$ and ferrous sulfide $(FeS)$.

(B) The Ellingham diagram is a graph that shows the temperature dependence of the stability of compounds.
It is a plot of the standard Gibbs free energy change $(\Delta G^{\circ})$ versus temperature $(T)$ for the formation of oxides and other compounds.

(B) Calcination: Used for hydrated carbonate or hydroxide ores,such as malachite,$CuCO_3 \cdot Cu(OH)_2$ (Matches $4$).
$(B)$ Roasting: Used for sulphide ores,such as galena,$PbS$ (Matches $1$).
$(C)$ Magnetic separation: Used for magnetic ores or gangue,such as magnetite,$Fe_3O_4$ (Matches $2$).
$(D)$ Carbon reduction of metal oxide: $A$ process involving the reduction of metal oxides using carbon in a furnace,which is a type of pyrometallurgy (Matches $3$).
Therefore,the correct matching is $A-4, B-1, C-2, D-3$.

(C) Statement-$I$ is correct. In the Hall-Heroult process,pure $Al_2O_3$ has a very high melting point and is a poor conductor of electricity. Adding $Na_3AlF_6$ (cryolite) and $CaF_2$ (fluorspar) lowers the melting point of the mixture and increases its electrical conductivity.
Statement-$II$ is incorrect. Zirconium $(Zr)$ is purified by the Van Arkel method,which involves the formation of a volatile iodide $(ZrI_4)$ followed by its thermal decomposition. Zone refining is typically used for semiconductors like $Si$ and $Ge$.

(A) The correct matching is:
$A. Al_2O_3 + 2NaOH + 3H_2O \rightarrow 2Na[Al(OH)_4]$ is an example of $\text{Leaching}$ $(V)$.
$B. Ni(CO)_4 \xrightarrow{230^{\circ}C} Ni + 4CO$ is an example of $\text{Vapour phase refining}$ $(III)$ (Mond process).
$C. Fe_2O_3 \cdot 3H_2O \xrightarrow{\Delta} Fe_2O_3 + 3H_2O$ is an example of $\text{Calcination}$ $(II)$.
$D. 2PbS + 3O_2 \rightarrow 2PbO + 2SO_2$ is an example of $\text{Roasting}$ $(I)$.
Therefore,the correct sequence is $A-V, B-III, C-II, D-I$.

(D) $(i)$ In the Mac-Arthur Forrest cyanide process,$Zn$ acts as a reducing agent to displace $Ag$ and $Au$ from their cyanide complexes: $2[M(CN)_2]^- + Zn \rightarrow [Zn(CN)_4]^{2-} + 2M$ (where $M = Ag$ or $Au$).
$(ii)$ Zinc is a low boiling point metal,so it is refined by distillation.
$(iii)$ Malachite is an ore of copper $(CuCO_3 \cdot Cu(OH)_2)$,not nickel.
Therefore,statements $(i)$ and $(ii)$ are correct.

(A, B, C) $1$. Copper matte is a mixture of $Cu_2S$ and $FeS$. Thus,statement $A$ is correct.
$2$. Pig iron is the iron obtained from blast furnace and contains about $4 \%$ carbon. Thus,statement $B$ is correct.
$3$. Blister copper gets its name from the blisters formed on its surface due to the evolution of $SO_2$ gas. Thus,statement $C$ is correct.
$4$. Van Arkel method is used for refining metals like $Zr$ and $Ti$,not nickel. Nickel is refined by the Mond process. Thus,statement $D$ is incorrect.
Note: In many competitive examinations,this question is considered a multiple-correct type question where $A$,$B$,and $C$ are all factually correct statements.

(D) In the extraction of copper from copper pyrites $(CuFeS_2)$,the ore is roasted to remove sulfur as $SO_2$.
$1$. $2 CuFeS_2 + O_2 \rightarrow Cu_2S + 2 FeS + SO_2$
$2$. $2 FeS + 3 O_2 \rightarrow 2 FeO + 2 SO_2$ (Option $B$ is related to the removal of iron impurity).
$3$. $FeO + SiO_2 \rightarrow FeSiO_3$ (Option $C$ is the slag formation step to remove iron).
$4$. $2 Cu_2S + 3 O_2 \rightarrow 2 Cu_2O + 2 SO_2$ (Option $A$ is the partial oxidation of copper matte).
Option $D$ $(SiO_2 + CaO \rightarrow CaSiO_3)$ is a reaction used in the extraction of iron (blast furnace) to remove acidic impurities like $SiO_2$ using basic flux $CaO$. It is not related to copper extraction.

(A, B, C, D) The Lintz and Donawitz $(L.D.)$ process is a highly efficient method for steel manufacturing.
Key advantages include:
$1$. The process is very quick due to the high-pressure oxygen blast.
$2$. It produces better quality steel by effectively removing impurities like $C$,$Si$,and $Mn$ as slag.
$3$. Scrap iron can be used as a raw material along with molten iron.
$4$. Operating costs are relatively low compared to older methods.
Since all the given options are valid advantages of the $L.D.$ process,the question implies selecting all that apply.

(C) In the industrial Bayer process,the sodium aluminate solution is cooled and seeded with freshly precipitated aluminium hydroxide $(Al(OH)_3)$.
This seeding induces the precipitation of $Al(OH)_3$ from the supersaturated solution.
Additionally,carbon dioxide $(CO_2)$ is often bubbled through the solution to neutralize the excess sodium hydroxide,which further promotes the precipitation of aluminium hydroxide.
Therefore,both methods are commonly practised in industrial settings.