Chemistry - General Principles and Process of Isolation of Elements
Exam Duration: 45 Mins Total Questions : 30
Metals generally occur in the native form due to their
- (a)
high electronegativity
- (b)
low density
- (c)
low reactivity
- (d)
high reactivity
Most abundant element in earth's crust ( in terms of number of atoms per 100 atoms) is
- (a)
Al
- (b)
Si
- (c)
O
- (d)
H
Sphalerite and siderite are the ores of the metals
- (a)
Cu and Fe
- (b)
Zn and Cu
- (c)
Zn and Fe
- (d)
Zn and Al
Lighter gangue particles are removed by washing in a current of water is called.
- (a)
liquation
- (b)
levigation
- (c)
cupellation
- (d)
leaching
Chemical used as a depressant in separating ZnS from PbS in froth floatation process is
- (a)
NaCN
- (b)
NaCl
- (c)
BaCl2
- (d)
ZnSO4
Which of the following ore is not concentrated by froth floatation process?
- (a)
Pyrolusite
- (b)
Pentlandite
- (c)
Zinc blende
- (d)
Copper pyrites
How do we separate two sulphide ores by froth floatation method?
- (a)
By adding pine oil
- (b)
By adding sodium cyanide
- (c)
By adding foaming agent
- (d)
By passing air
In the extraction of chlorine by electrolysis of brine,
- (a)
oxidation of Cl- ion to chlorine gas occurs
- (b)
reduction of Cl- ion to chlorine gas occurs
- (c)
for overall reaction, \(\Delta G^0\) has negative value
- (d)
a displacement reaction takes place
Smelting is involved in
- (a)
Fe2O3 + 3C\(\overset { Heat }{ \rightarrow } \) 2Fe + 3CO
- (b)
2PbS + 3O2\(\overset { Heat }{ \rightarrow } \) 2PbO + 2SO2
- (c)
Al2O3 . 2H2O \(\overset { Heat }{ \rightarrow } \) Al2O3 + 2H2O
- (d)
ZnCO3 \(\overset { Heat }{ \rightarrow } \) ZnO + CO2
Refractory materials are generally used in furnaces because
- (a)
they can withstand high temperature
- (b)
they are chemically inert
- (c)
they do not require replacement
- (d)
they possess great structural strength
Impure nickel can be purified by
- (a)
electrolytic refining
- (b)
Mond-carbonyl process
- (c)
zone-refining process
- (d)
van-Arkel process
The process in which 10 g of green wood is used is
- (a)
poling
- (b)
pickling
- (c)
anodising
- (d)
galvanishing
To obtain pure germanium, which of the following methods of refining is preferred?
- (a)
Liquation
- (b)
Zone-refining
- (c)
Electrolytic method
- (d)
Poling
Mond's process is used for the purification of
- (a)
Ni
- (b)
Ti
- (c)
Zr
- (d)
Hg
When copper ore is mixed with silica in a reverberatory furnace, copper metal is produced. The copper metal contains
- (a)
sulphides of copper (II) and iron (II)
- (b)
sulphides of copper (II) and iron (III)
- (c)
sulphides of copper (I) and iron (II)
- (d)
sulphides of copper (I) and iron (III)
In blast furnace, the highest temperature is in
- (a)
fusion zone
- (b)
reduction zone
- (c)
combustion zone
- (d)
slag zone
Match the following and choose the correct option.
| Column I | Column II |
| A. Zinc B. Tin C. Copper D. Magnesium |
p. Azurite q. Carnallite r. Calamine s. Cassiterite |
- (a)
A B C D r s p q - (b)
A B C D s r q p - (c)
A B C D s p q r - (d)
None of the above
In the froth floatation process, for the facilitation of ores, the ore particles float because
- (a)
their surface do not get easily wetted by water
- (b)
they are light
- (c)
they bear electrostatic charge
- (d)
they are not soluble
Cryolite is
- (a)
Na3AlF6 - used in the electrolysis of alumina to decrease the electrical conductivity
- (b)
Na3AlF6 - used in the electrolytic purification of alumina
- (c)
Na3AlF6 - used in the electrolysis of alumina
- (d)
Na3AlF6 - used in the electrolysis of alumina to lower the melting point of alumina.
Chemical composition of azurite mineral
- (a)
CuCO3 . 2Cu(OH)2
- (b)
Cu(HCO3)2. Cu(OH)2
- (c)
CuCO3 . CuO
- (d)
2CuCO3 . Cu(OH)2
The pyrometallurgical operations mainly involve the use of
- (a)
complexation
- (b)
high temperature
- (c)
sulphide ores
- (d)
electrolysis
In order to carry out a reduction process, temperature is selected to make
- (a)
\(\Delta G\) positive
- (b)
\(\Delta H\) positive
- (c)
\(\Delta G\) negative
- (d)
\(\Delta H\) negative
Brine is electrolysed by using inert electrodes. The reaction at anode is
- (a)
Cl-(aq) \(\rightarrow\) \(\frac{1}{2}\)Cl2(g) + e-; \({ E }_{ cell }^{ \circleddash }=1.36 \ \ V\)
- (b)
2H2O(l) \(\rightarrow\) O2(g) + 4H+ + 4e-; \({ E }_{ cell }^{ \circleddash }=1.23 \ \ V\)
- (c)
Na+(aq) + e- \(\rightarrow\) Na(s); \({ E }_{ cell }^{ \circleddash }=2.71 \ \ V\)
- (d)
H+(aq) + e- \(\rightarrow\) \(\frac{1}{2}\)H2(g); \({ E }_{ cell }^{ \circleddash }=0.00 \ \ V\)
In the metallurgy of aluminium
- (a)
Al3+ is oxidised to Al(s)
- (b)
graphite anode is oxidised to carbon monoxide and carbon dioxide
- (c)
oxidation state of oxygen changes in the reaction at anode
- (d)
oxidation state of oxygen changes in the overall reaction involved in the process
Extraction of gold and silver involves leaching the metal with CN- ion. The metal is recovered by
- (a)
displacement of metal by some other metal from the complex ion
- (b)
roasting of metal complex
- (c)
calcination followed by roasting
- (d)
thermal decomposition of metal complex
Which method of purification is represented by the following equation?
Ti(s) + 2I2(g) \(\overset {523 \ K }{ \rightarrow } \) TiI4(g) \(\overset {1700 \ Kl }{ \rightarrow } \) Ti(s) + 2I2(g)
- (a)
zone refining
- (b)
Cupellation
- (c)
Poling
- (d)
van-Arkel
Extraction of metal from the ore cassiterite involves
- (a)
carbon reduction of an oxide ore
- (b)
self-reduction of a sulphide ore
- (c)
removal of copper impurity
- (d)
removal of an iron impurity
Which of the following factors is of no significance for roasting sulphide ores to the oxides and not subjecting the sulphide ores to carbon reduction directly?
- (a)
Metal sulphides are thermodynamically more stable than CS2
- (b)
CO2 is thermodynamically more stable than CS2
- (c)
Metal sulphides are less stable than the corresponding oxides
- (d)
CO2 is more volatile than CS2
During the process of electrolytic refining of copper, some metals present as impurity settle as impurity settle as 'anode mud'. These are
- (a)
Fe and Ni
- (b)
Ag and Au
- (c)
Pb and Zn
- (d)
Se and Ag
Which one of the following ores is best concentrated by froth floatation mathod?
- (a)
Magnetite
- (b)
Cassiterite
- (c)
Galena
- (d)
Malachite
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