General Principles and Processes of Isolation of Elements Test

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General Principles and Processes of Isolation of Elements Test - 26

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Weekly Quiz Competition

Question 1
1 / -0

Thermite is a mixture of iron oxide and :

A
Aluminium powder

B
Zinc powder

C
Potassium metal

D
Sodium metal

Solution

Thermite is a mixture of iron oxide and aluminium powder.
It is used in alumonithermy or thermite process,
Aluminium reduces certain $$Fe_2O_3$$ Fe metal.
Question 2
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The method of zone refining of metals is based on the principle of:

A
greater noble character of the solid metal than that of the impurity

B
greater solubility of the impurity in the molten state than in the solid

C
greater mobility of the pure metal than that of impurity

D
higher melting point of the impurity than that of the pure metal

Solution

The zone refining method is based on the difference in the solubility of the impurities in the molten and in the solid state of the metal.
In zone-refining method the molten zone contains more impurity than the original metal.
Question 3
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In which of the following isolations no reducing agent is required?

A
Iron from haematite

B
Aluminium from bauxite

C
Mercury from cinnabar

D
Zinc from zinc blende

Solution

In the isolation of Mercury from cinnabar, no reducing agent is required. Mercury is obtained by the self-reduction method.

$$HgS +O_2 \xrightarrow {\Delta} HgO + SO_2$$

$$HgO + HgS \rightarrow Hg +SO_2$$
Question 4
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Zinc, cadmium and mercury are found in nature as sulphides. Values of standard reduction potentials for the half-reactions are :
$$M^{2+}(aq)\, +\, 2e^{-}\,
\rightarrow\, M(s)$$
$$\begin{matrix}M & E^{\circ}\\ Zn &-\,0.76\,V \\ Cd & -\,0.40\,V \\ Hg & +\,0.79\,V\end{matrix}$$ .
Which sulphides give element not oxide on roasting?

A
$$ZnS$$

B
$$HgS$$

C
$$CdS$$

D
None of these

Solution

$$\Delta G\ =\ -n{ E }^{ o }F\\ $$

$$\text{For the reduction to be favourable, } \Delta G \text { must be -ve. So,} \ { E }^{ o } \text{ should be positive}$$.
The highest positive value will be the most favourable to reduce to metal from the sulphide.
Question 5
1 / -0

Froth flotation is a process of _____________.

A
oxidation

B
reduction

C
refining

D
concentration

Solution

Froth flotation is a process of concentration. Froth floatation process is suitable for sulphide ores It is based on the difference in wetting properties of the ore and gangue with water and oil. This method is used for the concentration of $$FeCr_2O_4$$.
Question 6
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Purification of alumina takes place by _________________.

A
Bosch process

B
Hall's process

C
Hoope's process

D
Quartation process

Solution

Purification of alumina takes place by Hall's process. It involves fusion of bauxite with sodium carbonate in presence of little lime when alumina dissolves as sodium-meta-aluminate. Extraction of the fused mass with water followed by the extraction removes impurities.
Question 7
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The methods chiefly used for the extraction of lead and tin from their ores are respectively _________________.

A
self reduction and carbon reduction

B
self reduction and electrolytic reduction

C
carbon reduction and self reduction

D
cyanide process and carbon reduction

Solution

The methods chiefly used for the extraction of lead and tin from their ores are respectively self reduction and carbon reduction. Self reduction for lead is as follows.
$$2PbS+3O_2 \rightarrow 2PbO+2SO_2 \uparrow$$
$$PbS+2O_2 \rightarrow PbSO_4$$
$$2PbO + PbS \rightarrow 3Pb+SO_2 \uparrow$$
$$PbSO_4+PbS \rightarrow 2Pb+2SO_2 \uparrow$$
Carbon reduction for tin is as follows.
$$SnO_2+2C \rightarrow Sn+2CO \uparrow$$
Question 8
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Cryolite, $$Na_3AlF_6$$ is added to $$Al_2O_3$$ in Hall-Heroult process to ____ m.p. and to ___________ electrical conductivity.

A
higher, increase

B
higher, decrease

C
lower, increase

D
lower, decrease

Solution

In the Hall–Héroult process alumina, $$Al_2O_3$$, is dissolved in molten cryolite, $$Na_3AlF_6$$ to lower it's melting point for easier electrolysis. It also increases conductivity of the solution.
Question 9
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Most abundant metal in earth crust is___________.

A
Al

B
O

C
Fe

D
Si

Solution

Al is the most abundant metal in the earth's crust.

Aluminum is the third most abundant element (7.4%) of the earth's crust. Oxygen and silicon are the first and second most abundant elements.
Question 10
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Directions For Questions

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Which of the elements indicated by A, B, C and D is expected to be found in native state?

A
A

B
B

C
C

D
D

Solution

The element indicated by D is at the bottom of the electrochemical series.
Hence, it is expected to be found in the native state.

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General Principles and Processes of Isolation of Elements Test - 26

Result

General Principles and Processes of Isolation of Elements Test - 26

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SHARING IS CARING

Question 1

Aluminium powder

Zinc powder

Potassium metal

Sodium metal

Solution

Question 2

greater noble character of the solid metal than that of the impurity

greater solubility of the impurity in the molten state than in the solid

greater mobility of the pure metal than that of impurity

higher melting point of the impurity than that of the pure metal

Solution

Question 3

Iron from haematite

Aluminium from bauxite

Mercury from cinnabar

Zinc from zinc blende

Solution

Question 4

$$ZnS$$

$$HgS$$

$$CdS$$

None of these

Solution

Question 5

oxidation

reduction

refining

concentration

Solution

Question 6

Bosch process

Hall's process

Hoope's process

Quartation process

Solution

Question 7

self reduction and carbon reduction

self reduction and electrolytic reduction

carbon reduction and self reduction

cyanide process and carbon reduction

Solution

Question 8

higher, increase

higher, decrease

lower, increase

lower, decrease

Solution

Question 9

Al

O

Fe

Si

Solution

Question 10

A

B

C

D

Solution

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