MCQ Questions for Class 12 Engineering Chemistry General Principles And Processes Of Isolation Of Elements Quiz 12

Match the processes with the element for which they are used:
Column-I Column-II
(P) Bessemerisation (1) Ti

(Q) Van Arkel Method (2) Cast iron
(R) Carbon reduction (3) Sn
(S) Cupellation (4) Ag

0%
$P - 2, Q - 1, R - 3, S - 4$
0%
$P - 3, Q - 1, R - 2, S - 4$
0%
$P - 2, Q - 4, R - 3, S - 1$
0%
$P - 1, Q - 2, R - 3, S - 4$

What is the role of aniline or cresol when added in a forth floatation process?

0%
Stabilizer
0%
Depressant
0%
Wetting agent
0%
All of these

the mass of carbon anode consumed (giving only carbon dioxide) in the production of

$270Kg$ of aluminium metal from bauxite by the Hall's process is:

$2Al_2O_3+3C \to 4Al + 3CO_2$

0%
$180Kg$
0%
$270Kg$
0%
$240Kg$
0%
$90Kg$

Explanation

$2Al_2O_3 + 3C \longrightarrow 4Al + 3CO_2$

The mass of carbon consumed

$= \dfrac{3\times 12\times 270}{4\times 27} = 90kg$

Statement-I Froth Floatation process is based on the different wetting nature of ore and gangue particles
Statement-II Mustard oil is used as a frother in froth floatation

0%
Statement $I$ and $II$ are correct
0%
Both are false
0%
Statement $I$ is true but $II$ is flase
0%
Statement $II$ is true but $I$ is false

Which of the following gives an aldehyde on dry distillation?

0%
Calcium formate + Calcium acetate
0%
Calcium acetate + Calcium benzoate
0%
Calcium acetate
0%
Calcium benzoate

In solid

$CuS{ O }_{4 }.5{H }_{2 }O$ ,copper is coordinated to number of water molecule:-

0%
5
0%
4
0%
1
0%
2

Explanation

We know that,

$CuS{O_4}.5{H_2}O$ can also be written as

$[Cu{({H_2}O)_4}]S{O_4}.{H_2}O$ . Here, the four water molecules inside the coordination sphere are coordinated to Cu and the one water molecule which is outside the coordination sphere is hydrogen bonded.

Hence,(b) is the correct answer.

In electrolysis of

${\text{A}}{{\text{l}}_{\text{2}}}{{\text{O}}_{\text{3}}}$ by Hall-Heroult process, which of the following statement(s) is/are correct?

0%
Cryolite ${\text{N}}{{\text{a}}_{\text{3}}}\left[ {{\text{Al}}{{\text{F}}_{\text{6}}}} \right]\,$ lowers the meting point of ${\text{A}}{{\text{l}}_{\text{2}}}{{\text{O}}_{\text{3}}}\,$ increases its electrical conductivity.
0%
Al is obtained at cathode and probably $\,{\text{C}}{{\text{O}}_{\text{2}}}$ at anode
0%
Electrolysis is carried out in aqueous solution at anode
0%
Anode consist of graphite

Which reduction method is used in commercial extraction of Pb?

0%
Aluminium reduction
0%
Self Reduction
0%
Electrolytic reduction
0%
Hydrometallurgical reduction

Which of the following metals occurs in nature principally oxide ores.

0%
$Ca$
0%
$Co$
0%
$Cr$
0%
$Cu$

Explanation

$Ca$ occurs aa calcium oxide.So the naturally occuring oreof calcium is calcium oxide

$CaO$ .

Hence option A is correct.

The correct statement regarding the given Ellingham diagram is :

0%
Coke can't be used for the extraction of Cu from Cu $_{2}O$
0%
At 500 $^{\circ}$ C, Coke can be used for the extraction of Zn from ZnO.
0%
At 800 $^{\circ}$ C, Cu can be used for the extraction of Zn from ZnO.
0%
At 1400 $^{\circ}$ C, Al can be used for the extraction of Zn from ZnO.

According to Ellingham diagram, the oxidation reaction of carbon to carbon monoxide may be used to reduce which of the following oxides at the lower temperature?

0%
${\text{MgO}}$
0%
${\text{ZnO}}$
0%
${\text{A}}{{\text{l}}_{\text{2}}}{{\text{O}}_{\text{2}}}$
0%
${\text{C}}{{\text{u}}_{\text{2}}}{\text{O}}$

Which of the following Ellingham diagram ensures that at temperature

${T_3}$ ,

$A$ can reduce

$CO$ ,

$B$ can reduce

$AO$ ,and

$B$ can reduces

$CO$ but

$'A'$ cannot reduce

$BO$ ? (where

$A$ ,

$B$ and

$C$ are three unknown element ).

Hall-Heroult's process is given by:

0%
$Cr_2O_3 + 2Al \rightarrow Al_2O_3 + 2Cr$
0%
$Cu^{2+}(aq) + H_2(g) \rightarrow Cu(s) + 2H^+ (aq)$
0%
$ZnO + C \xrightarrow[]{Coke, 1673K} Zn + CO$
0%
$2Al_2O_3 + 3C \rightarrow 4Al + 3CO_2$

Explanation

In Hall-Heroult's process is given by

$2Al_2O_3 + 3C \rightarrow 4Al + 3CO_2$

$2Al_2O_3(\ell) \rightleftharpoons 4Al^{3+}(\ell) + 6O^{2\ominus} (\ell)$
At cathode:

$4Al^{3+}_{(\ell)} + 12e^{\ominus} \rightarrow 4Al(\ell)$
At Anode:

$6O^{2\ominus}_{(\ell)} \rightarrow 2O_2(g) + 12e^{\ominus}$

$3C + 3O_2 \rightarrow 3CO_2 (\uparrow)$

An incorrect statement about froth floatation method is:

0%
it is used to remove gangue from sulphide ores
0%
the mineral particles become wet by oils while gangue particles become wet by water
0%
collectors stabilize the froth
0%
to separate a mixture of ZnS and PbS depressant used is NaCN

In which of the following chemical leaching is used either in the extraction of metal or in the concentration of ore?

0%
Argentite
0%
Bauxite
0%
Alluvial sand containing gold
0%
All of these

A process of heating ore of a metal in excess of air below its melting point is called:

0%
Roasting
0%
Smelting
0%
Calcination
0%
All of these

With respect to an ore, Ellingham diagram helps to predict the feasibility if its:

0%
vapour phase refining
0%
zone refining
0%
electrolysis
0%
thermal reduction

Chief ore of Iron is

0%
Magnetite
0%
Siderite
0%
Haematite
0%
All of these

Which of the following metal ore is not concentrated by forth flotation method ?

0%
Sphalerite
0%
Argentite
0%
Galena
0%
Copper pyrites

Ellingham diagram is used for:

0%
Reduction
0%
Electrolysis
0%
Zone refining
0%
Van-Arkel

Explanation

With the help of Ellingham diagram we can select proper reducing agent

$(C_{(s)}$ or

$CO$ or

$Al)$ for metal compound

The sulphide ore for which the froth floatation process is not used commercially is:

0%
$ZnS$
0%
$CuS$
0%
$Ag_2S$
0%
$PbS$

The incorrect statement for Ellingham diagram is

0%
its a graphical representation of standard free energy change with temperature
0%
the graph of metal oxides generally moves upward with increase in temperature
0%
it represents thermodynamic and kinetic feasibility for the process
0%
The steep rise in the slope indicates the phase change

The ore having two metal atoms is :

0%
hematite
0%
galena
0%
magnetite
0%
copper pyrites

Explanation

An ore that has two different metal atoms is copper pyrite. Chemical formula of copper pyrite is

$CuFeS_2$ . It has both

$Cu$ and

$Fe$ metal. Thus, iron and copper both can be extracted from copper pyrites.

Hence the correct answer is option D.

Boron can be obtained by various methods but not by:

0%
Pyrolysis of $BI_3$ (Van Arkel)
0%
Reducing $BCl_3$ with $H_2$
0%
Electrolysis of fused $BCl_3$
0%
Oxidation of $B_2O_3$

The ore having two different metal atoms is:

0%
Hematite
0%
Galena
0%
Magnetite
0%
Copper pyrites

Which of the following is incorrect on the basis of the above Ellingham diagram for carbon?

0%
Up to $710^0C$ , the reaction of formation of $CO_2$ is energetically more favourable, but above $710^0C$ , the formation of CO is preferred
0%
In principle, carbon can be used to reduce any metal oxide at a sufficiently high temperature
0%
$\Delta S (C_{(s)} + \frac{1}{2}O_{2(g)} \rightarrow CO_{(g)} \ < \Delta S (C_{(s)} + O_{2(g)} \rightarrow CO_{2(g)})$
0%
Carbon reduces many oxides at elevated temperature because $\Delta G^0$ vs temperature line has a negative slope

The idea of froth floatation method came from a person X and this method is related to the process Y of ores. X and Y, respectively, are:

0%
fisher woman and concentration
0%
washer man and reduction
0%
washer woman and concentration
0%
fisher man and reduction

Tin is not refined by:

0%
Liquation
0%
Zone refining
0%
Poling
0%
Any of these

Explanation

Poling is a [metallurgical] method employed in the purification of copper which contains copper oxide as an impurity and also in the purification of tin ("Sn") which contains tin oxide (stannic oxide or

$SnO_{2}$ ) as an impurity. It was the use of these greenwood poles gave rise to the term "poling."

Liquation is suitable for metals with low melting points for example, tin. In this process, we heat the impure metal and then we let it flow on a sloped surface. The impurities will remain behind and the pure metal will collect at the bottom of the slope.

Zone refining is a special method we use to purify metals. It was the invention of William Pfann. It purifies metals to a very high degree. A rod of impure metal is placed in a container which we fill with inert gas. Then we place a circular heater around the rod at the top.

The melting point of tin is low. So zone refining is not suitable for Tin.

Hence, option B is correct.

Ag can be obtained from purified Zn-Ag alloy by:

0%
Distillation
0%
Poling
0%
Liquation
0%
Reduction

Find out A:

0%
$Cu_2S$
0%
$CuFeS_2$
0%
$FeS_2$
0%
$Fe_3O_4$

$Al_2O_3$ can be reduced by carbon at a temperature of :

0%
$30^0C$
0%
$500^0C$
0%
$2000^0C$
0%
$>2500^0C$

Explanation

Explanation:

An Ellingham diagram is a graph showing the temperature dependence of the stability for compounds. This analysis is usually used to evaluate the ease of reduction of metal oxides and sulfides. These diagrams were first constructed by Harold Ellingham in 1944.

Carbon cannot be used in the reduction of $Al_2O_3$ in metallurgy. Aluminum oxide is a very stable oxide and lies below the oxidation line of carbon in Ellingham Diagram. Hence, $Al_2O_3$ cannot be reduced by carbon as it is energetically not favorable.

A very high temperature is required. $Al_2O_3$ can be reduced by carbon at a temperature $>2500^{\circ}C$ as it is a stable oxide.

Option D is the correct answer.

Zn-Ag alloy formed in the upper layer of molten lead is skimmed off from the surface of the molten lead by perforated ladles. This alloy contains lead as impurity. This impurity of Pb is removed by:

0%
Distillation process
0%
Cupellation
0%
Liquation
0%
Bett's electrolysis

Select the correct statement(s):

0%
When tempreture is raised, a point will be reached where the graph crosses the $\Delta G = 0$ line. Below this tempreture, the free energy of formation of the oxide is negative, so the oxide is stable.
0%
When temperature is raised, a point will be reached where the graph crosses the $\Delta G = 0$ line. Above this tempreture, the free energy of formation of the oxide is positive, and the oxide becomes unstable, and should decompose into the metal and dioxygen
0%
Theoretically, all oxides can be decomposed to give the metal and dioxygen if a sufficiently high tempreture can be attained.
0%
Theoretically, all oxides cannot be decomposed to give the metal and dioxygen of a sufficiently high tempreture can be attained

Explanation

The Ellingham diagram for oxides shows several important features: When the temperature is raised, a point will be reached where the graph crosses the ΔG=0 line.

Below this temperature the free energy of the formation of the oxide is negative, so the oxide is stable. Above this temperature the free of formation of the oxide is positive, and the oxide becomes unstable and should decompose into the metal and dioxygen. And all oxides can be decomposed to give the metal and dioxygen if a sufficiently high temperature can be attained.

Ellingham diagram us a plot between

$\Delta G^{0}$ and

$T$

$\Delta G^{0}=-RTlnK$

The metal oxide (

$M_xO$ ) is stable at a point in a curve below which △G is negative. Above this point, the metal oxide is unstable. Hence option D is incorrect.

Options A, B and C are correct.

Select the correct statment(s):

0%
In hydrometallurgy, Zn is used as oxidizing agent in the purification of Ag from $[Ag(CN)_2)]^{\ominus}$
0%
When pine oil or eucalyptus oil is added into the water, it lowers down the surface tension by which froth is formed.
0%
Sodium ethyl xanthate is used as collector
0%
Basic copper carbonate or $PbSO_4$ is concentrated by forth floatation method by using an activator.

Explanation

Explanation:

Option A: In purification of silver, zinc is used as reducing agent not the oxidizing agent as per the equation given below:

$Ag_2S + NaCN \rightarrow Na[Ag(CN_2]+Na_2S$

Now, when zinc is used in purification of silver

$Na[Ag(CN_2]+Zn\rightarrow Na_2[Zn(CN_4]+Ag$

oxidation number of Zn changes from $0$ to $+2$

Hence it is clear that zinc is oxidised so it is used as reducing agent in purification of silver, so this option is wrong.

Option B:In the froth-flotation process, pine oil functions as a frothing agent or foaming agent. Other frothing agents include eucalyptus oil, xanthates or fatty acids. The frothing agent forms a foam (or froth) with air. Hence this is correct option.

Option C:

Froth floatation process used for the concentration of sulphide ore uses sodium ethly xanthate, $C_2H_5OCS_2Na$ as collector.
Other examples of collector include ethyl xanthate and potassium ethyl xanthate. They attach themselves to the grains of mineral by polar groups so that minerals become water repellent and pass on into the froth .Option C is correct

Option D:

Froth flotation process is used to concentrate sulphide ores, but in copper carbonate or lead sulphate we can use forth floatation method by using an activator. Option D is correct

Hence Option B, C, and D are correct answer

Which metal is generally found in native state?

0%
$Cu$
0%
$Au$
0%
$Al$
0%
$Fe$

In the extraction of aluminium by Hall-Heroult process, purified

$Al_2O_3$ is mixed with

$CaF_2$ to:

0%
Lower the melting point of $Al_2O_3$
0%
Increase the conductivity of molten mixture
0%
Reduce $Al^{3+}$ into Al(s)
0%
Acts as catalyst

In a mixture of

$PbS, ZnS,$ and

$FeS$ , each component is separated from the other by using the reagents in which of the following sequence in the froth floatation process?

0%
Potsassium ethyl xanthate, $KCN, NaOH$ , copper sulphate, acid
0%
$KCN, CuSO_4,$ acid
0%
Potassium ethyl xanthate, $KCN$
0%
None of these

During the process of electrolytic refining of copper, some metals present as impurity settle as 'anode mud'. These are:

0%
Fe and Ni
0%
Ag and Au
0%
Pb and Zn
0%
Sn and Ag

The ore that is concentrated by forth floatation process is:

0%
cinnabar
0%
bauxite
0%
malachite
0%
zincite

Froth floatation process is based on :

0%
Specific gravity of the ore particles
0%
Magnetic properties of the ore particles
0%
Wetting properties of the ore particles
0%
Electric properties of the ore particles

The impurities present in the mineral are called :

0%
flux
0%
gangue
0%
alloy
0%
slag

Which of the following ores is not concentrated by froth floatation process?

0%
Copper pyrites
0%
Pentlandite
0%
Pyrolusite
0%
Zinc blende

Explanation

Froth floatation method is commonly used for the concentration of the low-grade sulphide ore. The principal is based on the fact that gangue and ore particles have a different degree of wettability with water and pine oil. The ore particles are wetted by oil whereas gangue particles are wetted by water.

Copper pyrite is a sulphide ore (

$CuFeS_{2}$ ). Pentlandite is an iron-nickel sulphide ore

$(Fe,Ni)_{9}S_{8}$ and zinc blende (

$ZnS$ ) is also a sulphide ore hence it is concentrated by froth floatation process. While Pyrolusite is an oxide ore (

$MnO_{2}$ ) and cannot be concentrated by this process.

Hence, (C) is the correct option.

Select the correct statement:

0%
Dolomite is the ore of zinc
0%
Galena is the ore of mercury
0%
Pyrolusite is the ore of iron
0%
Cassiterite is the ore of tin

Explanation

Dolomite -

$MgCO_3.CaCO_3$ ; Ore of Magnesium

Galena -

$PbS$ ; Ore of lead

Pyrolusite -

$MnO_2$ ; Ore of Manganese

Cassiterite -

$SnO_2$ ; Ore of Tin

A mineral is called ore if:

0%
The metal present in the mineral is costly
0%
A metal can be extracted from it
0%
A metal can be extracted profitably from it
0%
A metal cannot be extracted from it

Radium is obtained from:

0%
pitchblende
0%
haematite
0%
monazite
0%
none of these

$Al_2O_3$ formation from aluminium and oxygen involves evolution of a large quantity of heat, which makes aluminium use in

0%
deoxidiser
0%
confectionary
0%
indoor photography
0%
thermite welding

Among the following incorrect statements is:

0%
Argantite and cuprite are oxide ores
0%
Calamine and azurite are carbonates
0%
Zinc blends and pyrites are sulphides
0%
Malachite and azurite are ores of copper

Explanation

uprite $(Cu_2O)$

Calamine $(ZnCO_3)$ and siderite $(FeCO_3)$

Zinc blende $(ZnS)$ and pyrites $(FeS_2)$

Malachite $(CuCO_3.Cu(OH)_2)$ and azurite $(Cu_3(CO_3)_2(OH)_2)$

Here Argentite is not an oxide.

Hence the correct answer is option A.

One of the natural minerals of sodium is tincal. Its formula is:

0%
$Na_{2}CO_{3}.10H_{2}O$
0%
$NaNO_{3}$
0%
$Na_{2}B_{4}O_{7}.10H_{2}O$
0%
$NaCl$

Explanation

Tincal, also called borax is sodium tetraborate decahydrate with chemical formula

$Na_2B_4O_7.10H_2O$ .

Potassium nitrate is called:

0%
Mohr's salt
0%
Indian saltpetre
0%
Gypsum
0%
Chile saltpetre

Explanation

Potassium nitrate

$(KNO_3)$ is also known as Indian saltpetre. This is because it is one of the several nitrogen-containing compounds and is very important as a crude salt in India. It is a major constituent of gun powder.

Hence the correct answer is option B.

Which of the following pairs are not correctly matched with respect to the extraction of metals from their ores

0%
Leaching process - Silver and gold from their native ores.
0%
Self reduction - Copper and mercury from their sulphide ores.
0%
Carbon/carbonmonoxide reduction - Iron and zinc from their oxide ores.
0%
Electrolytic reduction - Aluminium and tin from their oxide ores.

CBSE Questions for Class 12 Engineering Chemistry General Principles And Processes Of Isolation Of Elements Quiz 12 - MCQExams.com

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Practice Class 12 Engineering Chemistry Quiz Questions and Answers

CBSE Questions for Class 12 Engineering Chemistry General Principles And Processes Of Isolation Of Elements Quiz 12 - MCQExams.com

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Practice Class 12 Engineering Chemistry Quiz Questions and Answers

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