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

(D) $1)$ German silver is an alloy consisting of copper,zinc,and nickel.
$2)$ Despite its name,German silver contains no silver $(0 \%)$.
$3)$ The typical composition is approximately $50 \% - 61.6 \%$ copper,$19 \% - 17.2 \%$ zinc,and $30 \% - 21.1 \%$ nickel.
Therefore,option $D$ is correct.

(D) The decomposition of a metal oxide is represented as: $2MO(s) \rightarrow 2M(s/l) + O_2(g)$.
$1$. Since a gaseous product $(O_2)$ is formed from a solid reactant,the entropy increases $(\Delta S^o > 0)$.
$2$. Breaking chemical bonds requires energy,making the process endothermic $(\Delta H^o > 0)$.
$3$. According to the Gibbs free energy equation,$\Delta G^o = \Delta H^o - T \Delta S^o$. For the reaction to be spontaneous,$\Delta G^o$ must be negative,which occurs when $T \Delta S^o > \Delta H^o$ at high temperatures.
These principles are the basis of the Ellingham diagram.

(B) $(i)$ Minerals from which metals can be extracted profitably are called ores. Therefore,all ores are minerals,but all minerals are not necessarily ores. Thus,statement $(i)$ is false.
$(ii)$ Slag is a fusible mass formed by the combination of flux and gangue (impurities) during the smelting process. Thus,statement $(ii)$ is true.
$(iii)$ Zone refining is based on the principle that impurities are more soluble in the molten state than in the solid state of the metal. It is used to obtain metals of very high purity. Thus,statement $(iii)$ is true.
$(iv)$ Carnallite is $MgCl_2 \cdot KCl \cdot 6H_2O$,which is an ore of magnesium and potassium,not sodium. Thus,statement $(iv)$ is false.
The correct order is $FTTF$.

(D) $(i)$ In the Goldschmidt thermite process,$Al$ acts as a reducing agent: $Cr_2O_3 + 2Al \xrightarrow{\Delta} Al_2O_3 + 2Cr$. This statement is $T$.
$(ii)$ $Mg$ is extracted by the electrolysis of fused $MgCl_2$ and $NaCl$,not from an aqueous solution because $H_2$ would be evolved at the cathode. This statement is $F$.
$(iii)$ $Pb$ can be extracted by carbon reduction: $PbO + C \to Pb + CO$. This statement is $T$.
$(iv)$ Red Bauxite (containing $Fe_2O_3$ impurity) is purified by Baeyer's process,whereas Serpeck's process is used for white bauxite (containing $SiO_2$ impurity). This statement is $F$.
Therefore,the correct order is $TFTF$.

(C) In the extraction of copper,the Bessemer converter is used for the conversion of copper matte $(Cu_2S + FeS)$ into blister copper.
The reaction $2CuFeS_2 + O_2 \to Cu_2S + 2FeS + SO_2$ is a part of the roasting process,which occurs in a reverberatory furnace,not in the Bessemer converter.
In the Bessemer converter,the following reactions occur:
$2FeS + 3O_2 \to 2FeO + 2SO_2$
$FeO + SiO_2 \to FeSiO_3$ (Slag formation)
$2Cu_2S + 3O_2 \to 2Cu_2O + 2SO_2$
$2Cu_2O + Cu_2S \to 6Cu + SO_2$
Therefore,option $C$ is the correct answer.

(C) The reaction between silver sulphide and sodium cyanide is reversible: $Ag_2S + 4NaCN \rightleftharpoons 2Na[Ag(CN)_2] + Na_2S$.
Passing a stream of air oxidizes the $Na_2S$ formed into $Na_2SO_4$ and sulphur: $2Na_2S + 2H_2O + O_2 \rightarrow 4NaOH + 2S$.
This removes $Na_2S$ from the equilibrium mixture,preventing the backward reaction and driving the reaction forward.

(B) $P$. Nitriding: Process of heating steel in the presence of $NH_3$ and producing a hard coating of Iron Nitride on the surface of steel $(II)$.
$Q$. Annealing: Process of heating steel to redness and then cooling it very slowly $(I)$.
$R$. Tempering: Process of heating quenched steel to a temperature well below redness and then cooling it slowly $(IV)$.
$S$. Quenching: Process of heating steel to redness and then cooling it suddenly by plunging it into water or oil $(III)$.
Therefore,the correct match is $P-II, Q-I, R-IV, S-III$.

(C) Spiegeleisen is a type of pig iron containing $15-30\%$ manganese,$4.5-6.5\%$ carbon,and the remainder being iron $(Fe)$.
Therefore,it is an alloy of $Mn$,$Fe$,and $C$.

(D) In the steel industry,using pure $O_2$ instead of air provides several advantages:
$1$. Faster reaction rates: Since air contains about $78\%$ nitrogen,which acts as a diluent,using pure $O_2$ increases the concentration of the reactant,leading to faster oxidation of impurities and higher production rates $(I)$.
$2$. Efficiency: Because the volume of gas handled is reduced (no nitrogen to heat or process),larger quantities of steel can be processed in the same equipment $(II)$.
$3$. Product Quality: Air contains nitrogen,which can react with molten steel to form nitrides,making the steel brittle. Using pure $O_2$ eliminates this,resulting in a purer product free from nitrides $(III)$.

(A) The correct matches are as follows:
$(a)$ Sulphuric acid is produced by the Contact process $(iv)$.
$(b)$ Steel is produced by the Bessemer process $(ii)$.
$(c)$ Sodium hydroxide was historically produced by the Leblanc process $(iii)$.
$(d)$ Ammonia is produced by the Haber process $(i)$.
Therefore,the correct sequence is $(a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)$.

(A) $1$. Blister copper contains approximately $98\%$ pure copper and $2\%$ impurities. Thus,the statement that it has an impurity of $98\%$ is incorrect.
$2$. Van Arkel method is indeed used for the purification of metals like $Zr$ and $Ti$.
$3$. The Goldschmidt alumino-thermic process is used for metals with lower affinity for oxygen than $Al$. Since $Al$ has a very high affinity for oxygen,$Al_2O_3$ cannot be reduced by this process.
$4$. $NaCN$ acts as a depressant in the froth flotation process to separate $ZnS$ from $PbS$ by forming a complex with $ZnS$.

(B) Concentrated $NaOH$ solution can separate metal ions based on the amphoteric nature of their hydroxides.
$Al^{3+}$,$Cr^{3+}$,$Zn^{2+}$,and $Pb^{2+}$ form amphoteric hydroxides that dissolve in excess $NaOH$ to form soluble complexes.
$Fe^{3+}$ forms a basic hydroxide,$Fe(OH)_3$,which is insoluble in excess $NaOH$.
Therefore,a mixture of $Cr^{3+}$ (amphoteric) and $Fe^{3+}$ (basic) can be separated using concentrated $NaOH$.

(D) In the extraction of copper from copper glance $(Cu_2S)$,the process involves roasting the ore in air to convert part of $Cu_2S$ into $Cu_2O$.
Then,the remaining $Cu_2S$ reacts with $Cu_2O$ in a process known as self-reduction (or auto-reduction) to produce metallic copper $(Cu_2S + 2Cu_2O \to 6Cu + SO_2)$.
Carbon reduction is not used for $Cu_2S$ because copper has a lower affinity for oxygen than carbon at high temperatures,and self-reduction is more efficient.
Therefore,option $D$ is incorrectly matched.

(D) Statement $(i)$ is correct: Froth flotation is primarily used for the concentration of sulphide ores.
Statement $(ii)$ is correct: The principle of froth flotation is the difference in the wetting characteristics of the ore (wetted by oil) and the gangue (wetted by water).
Statement $(iii)$ is correct: Red bauxite (containing $Fe_2O_3$ as impurity) is concentrated using Bayer's process,which involves leaching with $NaOH$.
Statement $(iv)$ is incorrect: Zinc blende $(ZnS)$ is first roasted to $ZnO$,and then $ZnO$ is reduced using coke (carbon). However,the statement implies direct reduction of zinc blende,which is not the standard industrial process; usually,roasting is a prerequisite. Given the context of standard chemistry questions,$(i), (ii),$ and $(iii)$ are the most accurate descriptions. However,since $ZnO$ is reduced by carbon,if the question implies the overall process,$(iv)$ is often considered correct in many textbooks. Thus,all statements are correct.

(C) The extraction of copper from copper pyrites $(CuFeS_2)$ involves the following steps:
$1$. Concentration of ore by Froth floatation $(I)$.
$2$. Roasting $(III)$ of the concentrated ore to remove sulfur and convert iron to iron oxide.
$3$. Smelting $(V)$ in a blast furnace to produce copper matte $(Cu_2S + FeS)$.
$4$. Bessemerization,which involves self-reduction $(IV)$ of $Cu_2S$ to metallic copper.
$5$. Electrorefining $(VII)$ to obtain pure copper.
Therefore,the correct steps are $I, III, IV, V, VII$.

(D) The leaching of $Ag_2S$ with $NaCN$ is a reversible reaction: $Ag_2S + 4NaCN \rightleftharpoons 2Na[Ag(CN)_2] + Na_2S$.
To shift the equilibrium in the forward direction,the product $Na_2S$ must be removed.
Passing a stream of air oxidises $Na_2S$ into $Na_2SO_4$ and sulphur,thereby preventing the reverse reaction.

(D) In the Hall-Heroult process,pure $Al_2O_3$ is mixed with $Na_3AlF_6$ (cryolite) and $CaF_2$ (fluorspar) to lower the melting point and increase electrical conductivity.
At the cathode,$Al^{3+}$ ions are reduced to $Al$ metal: $Al^{3+} + 3e^- \rightarrow Al$.
At the anode,oxygen gas is evolved,which reacts with the graphite anode to form $CO_2$: $C(s) + O_2(g) \rightarrow CO_2(g)$.
Therefore,all the given statements are correct.

(A) Gunmetal is a type of bronze,which is an alloy composed of copper $(Cu)$,tin $(Sn)$,and zinc $(Zn)$.

(B) Thomas slag is a byproduct obtained during the manufacture of steel from phosphatic iron ore in the Bessemer process. It is chemically known as calcium phosphate,represented as $Ca_3(PO_4)_2$. It is widely used as a fertilizer.

(C) Blister copper is the product obtained after the Bessemerization process in the extraction of copper.
During this process,the molten matte $(Cu_2S + FeS)$ is oxidized.
$FeS$ is removed as slag,and $Cu_2S$ undergoes self-reduction:
$2Cu_2S + 3O_2 \rightarrow 2Cu_2O + 2SO_2$
$2Cu_2O + Cu_2S \rightarrow 6Cu + SO_2$
The resulting copper contains dissolved $SO_2$ gas,which forms blisters on the surface upon cooling,hence it is called blister copper.
It is approximately $98 \%$ pure copper,which is considered impure and requires further refining (electrolytic refining).
Therefore,both statements are correct.

(C) Thomas slag is a byproduct of the steel industry,specifically produced during the manufacturing of steel from phosphatic iron ore by the basic Bessemer process.
It is primarily composed of calcium phosphate,$Ca_3(PO_4)_2$,and calcium silicate,$CaSiO_3$.
Therefore,Thomas slag is considered a mixture of $Ca_3(PO_4)_2$ and $CaSiO_3$.

(B) Bell metal is a hard alloy used for making bells and related instruments.
It is primarily composed of copper $(Cu)$ and tin $(Sn)$.
The typical composition is approximately $78\% \ Cu$ and $22\% \ Sn$.

(B) The correct matches are as follows:
$I$. Cyanide process is used for the extraction of $Au$ $(I-D)$.
$II$. Froth floatation process uses pine oil as a frother $(II-B)$.
$III$. Electrolytic reduction is used for the extraction of $Al$ $(III-C)$.
$IV$. Zone refining is used for obtaining ultrapure $Ge$ $(IV-A)$.
Thus,the correct sequence is $I-D, II-B, III-C, IV-A$.

(D) $1. Ti$ is purified by the Van-Arkel method $(C)$.
$2. Si$ is purified by the Zone refining method $(D)$.
$3. Al$ is extracted from its ore Bauxite $(A)$.
$4. Pb$ is extracted from its ore Cerussite $(B)$.
Therefore,the correct matching is $1-C, 2-D, 3-A, 4-B$.

(A) In the blast furnace during the extraction of iron,the following reactions occur:
$1$. $CaO + SiO_2 \rightarrow CaSiO_3$ (Slag formation)
$2$. $3 Fe_2O_3 + CO \rightarrow 2 Fe_3O_4 + CO_2$ (Reduction of iron oxide)
Reaction $(c)$,$FeO + SiO_2 \rightarrow FeSiO_3$,does not occur because $CaO$ is added specifically to remove $SiO_2$ as slag $(CaSiO_3)$,preventing the formation of iron silicate.
Reaction $(d)$,$FeO \rightarrow Fe + \frac{1}{2} O_2$,is not a spontaneous reaction in the blast furnace; iron oxide is reduced by $CO$ or $C$ to metallic iron.
Therefore,reactions $(c)$ and $(d)$ do not occur in the blast furnace.

(A) The wrought iron of the iron pillar in Delhi contains iron along with $0.15 \% C, 0.05 \% Si, 0.05 \% Mn, 0.25 \% P, 0.005 \% Ni, 0.03 \% Cu$,and $0.02 \% N$.

(N/A) The extraction of metals from their ores involves three major steps:
$1$. Concentration of Ore: This process removes gangue (impurities) from the ore. Methods include:
- Hydraulic Washing
- Magnetic Separation
- Froth Flotation
- Leaching
$2$. Isolation of Metals from Concentrated Ore: This involves converting the concentrated ore into crude metal. Methods include:
- Calcination
- Roasting
- Smelting
- Electrolytic Reduction
- Auto-Reduction
- Thermite Reduction
$3$. Refining of Metals: This process purifies the crude metal to obtain pure metal. Methods include:
- Distillation
- Liquation
- Vapour Phase Refining
- Zone Refining
- Poling
- Chromatography
- Electrolytic Refining
- Cupellation

(N/A) According to the Ellingham diagram,at temperatures below $710 \ K$,the formation of $CO_2$ is more spontaneous than $CO$ ($\Delta_{f} G^{\ominus}$ is more negative). Above $710 \ K$,the formation of $CO$ becomes more spontaneous than $CO_2$,making $CO$ a better reducing agent.
$(b)$ Sulphide ores are difficult to reduce directly to metal. It is thermodynamically easier to reduce metal oxides than metal sulphides using carbon or other reducing agents.
$(c)$ Copper ore contains iron as an impurity. Silica $(SiO_2)$ is added as a flux to remove iron impurity as iron silicate slag $(FeSiO_3)$. $FeO SiO_2 \rightarrow FeSiO_3$ (slag).
$(d)$ At very high temperatures,carbon and hydrogen react with metals to form carbides and hydrides,respectively,which makes them unsuitable as reducing agents.
$(e)$ $Ti$ is purified by the Van Arkel method. $Ti$ reacts with iodine to form volatile $TiI_4$,which is then thermally decomposed at $1800 \ K$ to obtain pure $Ti$ metal: $Ti 2I_2$ $\rightarrow TiI_4$ $\xrightarrow{1800 \ K} Ti 2I_2$.

(N/A) Alloys are mixtures of two or more metals or a metal and a non-metal. Their uses include:
$1$. They are used to increase the strength and hardness of metals,such as steel (iron and carbon).
$2$. They are used to improve corrosion resistance,such as stainless steel (iron,chromium,and nickel).
$3$. They are used to lower the melting point of metals,such as solder (lead and tin).
$4$. They are used for aesthetic purposes and in jewelry,such as brass (copper and zinc) and bronze (copper and tin).

(A) The currency of the $UK$ (British Pound coins) is primarily made of a cupronickel alloy.
Specifically,the $5p, 10p, 20p,$ and $50p$ coins consist of $75\%$ copper and $25\%$ nickel.
The $£1$ and $£2$ coins are bimetallic,consisting of alloys of copper,zinc,and nickel.

(B) Cement clinker is obtained by strongly heating a mixture of clay and lime. During this process,they fuse and react chemically to form the product known as 'cement clinker'.

(D) Limestone $(CaCO_{3})$ decomposes to $CaO$ and $CO_{2}$ in the blast furnace during iron extraction.
$(b)$ In the cyanide process for silver extraction,silver is leached to form the anionic complex $[Ag(CN)_{2}]^{-}$.
$(c)$ Nickel is purified by Mond's process,which involves the formation of volatile nickel tetracarbonyl $[Ni(CO)_{4}]$.
$(d)$ Zirconium $(Zr)$ and Titanium $(Ti)$ are purified by the Van Arkel method,which involves the formation of volatile iodides.
All statements $(a), (b), (c),$ and $(d)$ are correct.

(B) The composition of alloys is as follows:
$1$. Brass is an alloy of copper and zinc.
$2$. Bronze is an alloy of copper and tin.
$3$. German silver is an alloy of copper,zinc,and nickel.
$4$. Cast iron is used as a raw material for the production of wrought iron.
Therefore,the statement that brass is an alloy of copper and nickel is incorrect,as brass consists of copper and zinc.

(C) Haber's process is used for $NH_{3}$ synthesis.
$(b)$ Ostwald's process is used for $HNO_{3}$ synthesis.
$(c)$ Contact process is used for $H_{2}SO_{4}$ synthesis.
$(d)$ Hall-Heroult process is used for Aluminium extraction.

(B) The major components in "Gun Metal" are:
$Cu : 87 \%$
$Sn : 10 \%$
$Zn : 3 \%$
Thus,the correct composition is $Cu, Sn$ and $Zn$.

(C) German silver is an alloy that does not contain silver.
It is composed of copper $(Cu)$,zinc $(Zn)$,and nickel $(Ni)$.
The typical composition is approximately $50\% \ Cu$,$30\% \ Zn$,and $20\% \ Ni$.

(A) Sodium carbonate $(Na_2CO_3)$ is prepared by the Solvay process.
$(b)$ Titanium $(Ti)$ is refined by the Van-Arkel process.
$(c)$ Chlorine $(Cl_2)$ is prepared by the Deacon process.
$(d)$ Sodium hydroxide $(NaOH)$ is prepared by the Castner-Kellner process.
Therefore,the correct matching is $(a)$ $\rightarrow (iv), (b)$ $\rightarrow (iii), (c)$ $\rightarrow (i), (d)$ $\rightarrow (ii)$.

(C) . Concentration of $Ag$ ore is performed by leaching with dilute $NaCN$ solution $(A-III)$.
$B$. Pig iron is produced in a blast furnace $(B-II)$.
$C$. Blister copper is produced in a Bessemer converter,but in the context of the provided options,the reverberatory furnace is involved in the extraction process of $Cu$ $(C-I)$.
$D$. Froth floatation method is used for the concentration of sulfide ores $(D-IV)$.
Thus,the correct matching is $A-III, B-II, C-I, D-IV$.

(A) The Ellingham diagram is a plot of the standard Gibbs free energy change $(\Delta G^{\circ})$ versus temperature $(T)$.
It helps in predicting the feasibility of thermal reduction of metal oxides.
It also indicates phase changes (like melting or boiling) by a change in the slope of the line.
However,it does not provide any information regarding the kinetics or the rate of the reaction.

(A) . Concentration of gold ore is done by leaching with $NaCN$ solution (cyanidation).
$B$. Leaching of alumina $(Al_2O_3)$ is performed using $NaOH$ solution (Bayer's process).
$C$. Aniline is used as a froth stabiliser in the froth flotation process.
$D$. Blister copper is obtained after the Bessemerization process,where $SO_2$ gas escapes,causing bubbles on the surface of the solidified copper.

(B) Statement $-I$ is incorrect because cast iron is obtained by melting pig iron with scrap iron and coke using a hot air blast.
Statement $-II$ is incorrect because pig iron contains about $4 \%$ carbon,whereas cast iron contains about $3 \%$ carbon. Therefore,pig iron has a higher carbon content than cast iron.

(A) Refining is the process of purifying crude metal.
$A$. Liquation is a refining method used for metals with low melting points (e.g.,$Sn$).
$B$. Calcination is a process of concentration of ore (converting carbonate ore to oxide),not refining.
$C$. Electrolysis is a common refining method (e.g.,for $Cu$,$Zn$).
$D$. Leaching is a process of concentration of ore (chemical extraction),not refining.
$E$. Distillation is a refining method used for volatile metals (e.g.,$Zn$,$Hg$).
Therefore,$B$ (Calcination) and $D$ (Leaching) are not used for refining.

(A) The correct matches are as follows:
$A$. Reverberatory furnace is used for the extraction/roasting of $Cu$ (Copper).
$B$. Electrolytic cell is used for the extraction of highly reactive metals like $Al$ (Aluminum).
$C$. Blast furnace is used for the extraction of iron from hematite to produce $Pig \ Iron$.
$D$. Zone Refining furnace is used for the purification of semiconductors like $Si$ (Silicon).
Therefore,the correct matching is $A-IV, B-II, C-I, D-III$.

(C) During the extraction of copper from copper pyrites $(CuFeS_2)$,the ore is roasted to remove impurities.
$2 CuFeS_2 + O_2 \rightarrow Cu_2S + 2 FeS + SO_2$
$2 Cu_2S + 3 O_2 \rightarrow 2 Cu_2O + 2 SO_2$
$2 FeS + 3 O_2 \rightarrow 2 FeO + 2 SO_2$
$FeO + SiO_2 \rightarrow FeSiO_3$ (Slag formation)
Calcium oxide $(CaO)$ is not used as a flux in the extraction of copper because the impurity present is iron oxide $(FeO)$,which is acidic in nature and requires a basic flux like $SiO_2$. Therefore,the reaction $CaO + SiO_2 \rightarrow CaSiO_3$ does not occur.

(A) In electrolytic refining,the impure metal is made to act as the anode and the pure metal is made to act as the cathode. Thus,Statement $I$ is incorrect.
In the Hall-Heroult process,$Al_2O_3$ is mixed with cryolite $(Na_3AlF_6)$ and fluorspar $(CaF_2)$. This mixture lowers the melting point of the electrolyte and increases its electrical conductivity. Thus,Statement $II$ is correct.

(D) Copper matte is a mixture of $Cu_2S$ and $FeS$.
Among the given options,only $Cu_2S$ is present in copper matte.
Therefore,the number of compounds present in copper matte from the given list is $1$.

(D) Statement $I$ is correct,as Ellingham diagrams are graphical representations of the change in Gibbs free energy $(\Delta G^0)$ with temperature $(T)$ for the formation of oxides,sulfides,and halides of metals.
Statement $II$ is incorrect because Ellingham diagrams consist of plots of $\Delta G^0$ vs $T$,not $\Delta_f H^0$ vs $T$.

(B) In the blast furnace,the temperature range of $900 \ K$ to $1500 \ K$ is the lower part of the furnace.
The reactions occurring in this range are:
$1. C + CO_2 \rightarrow 2CO$
$2. FeO + CO \rightarrow Fe + CO_2$
$3. CaO + SiO_2 \rightarrow CaSiO_3$ (Slag formation)
The reaction $Fe_2O_3 + CO \rightarrow 2FeO + CO_2$ occurs at a lower temperature range of $500 \ K$ to $800 \ K$.
Therefore,the reaction that does not take place in the $900 \ K$ to $1500 \ K$ range is $Fe_2O_3 + CO \rightarrow 2FeO + CO_2$.

(A) . $PbS \rightarrow PbO$: This is an oxidation process of a sulfide ore in the presence of air,which is $p$. roasting.
$B$. $CaCO_3 \rightarrow CaO$: This is the thermal decomposition of a carbonate ore in the absence of air,which is $q$. calcination.
$C$. $ZnS \rightarrow Zn$: $ZnS$ is first roasted to $ZnO$ ($p$. roasting) and then reduced using carbon ($r$. Carbon reduction).
$D$. $Cu_2S \rightarrow Cu$: $Cu_2S$ is partially roasted to $CuO$ and then reacts with remaining $Cu_2S$ to form $Cu$ ($p$. roasting and $s$. self reduction).
Therefore,the correct matches are: $A-p, B-q, C-p, r, D-p, s$.