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Published on: 27/06/2019
mostly asked multiple choice questions in twelfth standard chemistry metallurgy
Download Tamil Nadu 12th Standard Chemistry question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.
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1.
Which of the following is not true with respect to Ellingham diagram?
Free energy changes follow a straight line. Deviation occurs when there is a phase change.
The graph for the formation of CO2 is a straight line almost parallel to free energy axis.
Negative slope of CO shows that it becomes more stable with increase in temperature.
Positive slope of metal oxides shows that their stabilities decrease with increase in temperature.
2.
Which of the following reduction is not thermodynamically feasible?
\({ Cr }_{ 2 }{ O }_{ 3 }+2Al\longrightarrow { Al }_{ 2 }{ O }_{ 3 }+2Cr\)
\(\mathrm{Al}_2 \mathrm{O}_3+2 \mathrm{Cr} \longrightarrow \mathrm{Cr}_2 \mathrm{O}_3+2 \mathrm{Al}\)
\(3Ti{ O }_{ 2 }+4Al\longrightarrow 2A{ l }_{ 2 }{ O }_{ 3 }+3Ti\)
none of these
3.
In the Ellingham diagram, for the formation of carbon monoxide________.
\(\left( \cfrac { \Delta { S }^{ 0 } }{ \Delta T } \right) \) is negative
\(\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right) \) is positive
\(\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right) \) is negative
initially \(\left( \cfrac { \Delta T }{ \Delta { G }^{ 0 } } \right) \) is positive, after 700oC,\(\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right) \) is negative
4.
Which of the following plot gives Ellingham diagram
\(\Delta S \ \text{Vs} \ T\)
\(\Delta { G }^{ 0 }\ \text{Vs} \ T\)
\(\Delta { G }^{ 0 }\ \text{Vs} \ \frac { 1 }{ T } \)
\(\Delta { G }^{ 0 }\ \text{Vs} \ { T }^{ 2 }\)
5.
6.
The incorrect statement among the following is______.
Nickel is refined by Mond’s process
Titanium is refined by Van Arkel’s process
Zinc blende is concentrated by froth floatation
In the metallurgy of gold, the metal is leached with dilute sodium chloride solution
7.
Which of the following is used for concentrating ore in metallurgy?
Leaching
Roasting
Froth floatation
Both (a) and (c)
8.
The following set of reactions are used in refining Zirconium
\(Zr \text{(impure)}+2I_{ 2 }\overset { 523k }{ \longrightarrow } ZrI_{ 4 }\)
\({ ZrI }_{ 4 }\overset { 1800K }{ \longrightarrow } Zr \text{(pure)}+{ 2I }_{ 2 }\)This method is known as ______.
Liquation
Van Arkel process
Zone refining
Mond’s process
9.
Considering Ellingham diagram, which of the following metals can be used to reduce alumina?
Fe
Cu
Mg
Zn
10.
11.
Cupellation is a process used for the refining of________.
Silver
Lead
Copper
iron
12.
Zinc is obtained from ZnO by________.
Carbon reduction
Reduction using silver
Electrochemical process
Acid leaching
13.
In the extraction of aluminium from alumina by electrolysis, cryolite is added to_______.
Lower the melting point of alumina
Remove impurities from alumina
Decrease the electrical conductivity
Increase the rate of reduction
14.
Which one of the following ores is best concentrated by froth – floatation method?
Magnetite
Haematite
Galena
Cassiterite
15.
Flux is a substance which is used to convert_______.
Mineral into silicate
Infusible impurities to soluble impurities
Soluble impurities to infusible impurities
All of these
16.
Electrochemical process is used to extract_______.
Iron
Lead
Sodium
silver
17.
Which one of the following is not feasible
Zn(s) + Cu2+(aq) \(\rightarrow\) Cu(s) + Zn2+(aq)
Cu(s)+ Zn2+(aq)\(\rightarrow\) Zn(s) + Cu2+(aq)
Cu(s) + 2Ag+(ag)\(\rightarrow\) 2Ag(s) + Cu2+(aq)
Fe(s) + Cu2+(aq) \(\rightarrow\) Cu(s)+ Fe2+(aq)
18.
Wolframite ore is separated from tinstone by the process of________.
Smelting
Calcination
Roasting
Electromagnetic separation
19.
Match items in column - I with the items of column – II and assign the correct code.
| Column-I | Column-II | ||
| A. | Cyanide process | (i) | Ultrapure Ge |
| B | Froth floatation process | (ii) | Dressing of ZnS |
| C | Electrolytic reduction | (iii) | Extraction of Al |
| D | Zone refining | (iv) | Extraction of Au |
| (v) | Purification of Ni | ||
| A | B | C | D |
| (i) | (ii) | (iii) | (iv) |
| A | B | C | D |
| (iii) | (iv) | (v) | (i) |
| A | B | C | D |
| (iv) | (ii) | (iii) | (i) |
| A | B | C | D |
| (ii) | (iii) | (i) | (v) |
20.
Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?
\(\Delta { G }_{ f }^{ 0 }\) of sulphide is greater than those for CS2 and H2S
\(\Delta { G }_{ r }^{ 0 }\) is negative for roasting of sulphide ore to oxide
Roasting of the sulphide to its oxide is thermodynamically feasible
Carbon and hydrogen are suitable reducing agents for metal sulphides
1.
(b)
The graph for the formation of CO2 is a straight line almost parallel to free energy axis.
2.
(b)
\(\mathrm{Al}_2 \mathrm{O}_3+2 \mathrm{Cr} \longrightarrow \mathrm{Cr}_2 \mathrm{O}_3+2 \mathrm{Al}\)
3.
(c)
\(\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right) \) is negative
4.
(b)
\(\Delta { G }^{ 0 }\ \text{Vs} \ T\)
5.
(b)
6.
(d)
In the metallurgy of gold, the metal is leached with dilute sodium chloride solution
7.
(d)
Both (a) and (c)
8.
(b)
Van Arkel process
9.
(c)
Mg
10.
(c)
11.
(a)
Silver
12.
(a)
Carbon reduction
13.
(a)
Lower the melting point of alumina
14.
(c)
Galena
15.
(b)
Infusible impurities to soluble impurities
16.
(c)
Sodium
17.
(b)
Cu(s)+ Zn2+(aq)\(\rightarrow\) Zn(s) + Cu2+(aq)
18.
(d)
Electromagnetic separation
19.
(c)
| A | B | C | D |
| (iv) | (ii) | (iii) | (i) |
20.
(d)
Carbon and hydrogen are suitable reducing agents for metal sulphides
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