General Principles and Processes of Isolation of Elements Test

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General Principles and Processes of Isolation of Elements Test - 37

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Weekly Quiz Competition

Question 1
1 / -0

Point out the correct statement:

A
Below $$710^{\circ}C$$, $$C$$ is better reducing agent than $$CO$$

B
Below $$710^{\circ}C$$, $$CO$$ is better reducing agent than $$C$$

C
Below $$710^{\circ}C, CO$$ is an oxidising agent

D
Below $$710^{\circ}C, CO_{2}$$ is a reducing agent

Solution

Below $$710 ^o C, \ CO$$ is better reducing agent than $$C$$.
Below $$710 ^o C$$, $$\displaystyle \Delta G^o$$ is more negative for the reaction $$\displaystyle C+O_2 \rightarrow CO_2$$ than for the reaction $$\displaystyle 2CO +O_2 \rightarrow 2CO_2$$
Question 2
1 / -0

The function of potassium ethyl xanthate in froth floatation process is to make the ore :

A
attracted towards water

B
water repellant

C
lighter

D
heavier

Solution

The function of potassium ethyl xanthate in froth floatation process is to make the ore Water repellant. The metallic ore particles are preferentially wetted by the oil and rise to the surface along with the froth. Other oils used are pine oil, eucalyptus oil and fatty acids.
Question 3
1 / -0

The process of leaching, alumina using sodium carbonate is called _________.

A
bayer's process

B
decomposition

C
cyanide process

D
hall's process

Solution

Bauxite is concentrated through Hall’s process, in which sodium aluminate is prepared using sodium carbonate in bauxite. When excess carbon dioxide is passed through sodium aluminate in the presence of water, it forms aluminium hydroxide along with sodium carbonate. When dried aluminium hydroxide is ignited, alumina is formed.
Question 4
1 / -0

A process employed for the concentration of sulphide ore is:

A
froth floatation

B
gravity separation

C
froth separation

D
gravity floatation

Solution

It is a method of separation of ore and gangue by preferential wetting.
Principle of separation is ore ore is preferentially wetted by the oil and hence it floats on the top of the foam and the gangue is preferentially wetted by water and settles down. It is generally applied for sulphide ores.
Question 5
1 / -0

Gold does not occur in the combined form. It does not react with air or water. It is in the_______state.

A
native

B
combined

C
original

D
liquid

Solution

Gold is less reactive element. In electrochemical series, it is lower than Hydrogen. It doesn't react with anything. So it occurs as native metal.
Question 6
1 / -0

Thermal decomposition of ammonium dichromate gives:

A
$${ N }_{ 2 },{ H }_{ 2 }O$$ and $${ Cr }_{ 2 }{ O }_{ 3 }$$

B
$${ N }_{ 2 },N{ H }_{ 3 }$$ and $$CrO$$

C
$${ \left( N{ H }_{ 4 } \right) }_{ 2 }Cr{ O }_{ 4 }$$ and $${ H }_{ 2 }O$$

D
$${ N }_{ 2 },{ H }_{ 2 }O$$ and $$Cr{ O }_{ 3 }$$

E
$${ N }_{ 2 },{ H }_{ 2 }O$$ and $$CrO$$

Solution

Thermal decomposition of ammonium dichromate $${ \left( N{ H }_{ 4 } \right) }_{ 2 }{ Cr }_{ 2 }{ O }_{ 7 }$$ on heating gives $${ N }_{ 2 },{ Cr }_{ 2 }{ O }_{ 3 }$$ and $${ H }_{ 2 }O$$ as follows:
$${ \left( N{ H }_{ 4 } \right) }_{ 2 }{ Cr }_{ 2 }{ O }_{ 7 }\xrightarrow [ ]{ \quad \quad \Delta \quad \quad } { N }_{ 2 }+{ Cr }_{ 2 }{ O }_{ 3 }+4{ H }_{ 2 }O$$
Question 7
1 / -0

The purest zinc is made by.

A
Electrolytic refining

B
Zone refining

C
The van-Arkel method

D
Mond process

Solution

Zinc is purified by zone-refining method.
Question 8
1 / -0

Which of the following is an oxide ore?

A
Malachite

B
Haematite

C
Chalcopyrite

D
Zinc blende
Solution
Hint: The ore in which the desired element is present in the form of its oxide is termed oxide ore.

Explanation:
- Malachite is widespread copper ore. Its chemical formula is $$Cu_2CO_3\left ( OH \right )_2$$. It is also known as Copper carbonate hydroxide mineral.
- Haematite is an important ferric oxide of the chemical formula $$Fe_2O_3$$. It is an oxide ore.
- Chalcopyrite is an important copper mineral having the chemical formula $$CuFeS_2$$. It is a sulphide type of copper and iron ore.
- Zinc blende is important iron ore. It is otherwise known as zinc sulfide with the chemical formula $$ZnS$$.
Final Answer:

Therefore, haematite is an oxide ore.

Thus, the final answer is option $$B$$.
Question 9
1 / -0

In chromite ore, the oxidation number of iron, and chromium are respectively.

A
+3, +2

B
+3, +6

C
+2, +6

D
+2, +3

Solution

Chromite or chrome iron ore is $$FeCr_2O_4$$. Its actual composition is $$FeO.Cr_2O_3$$.

In $$FeO$$, oxidation state of $$Fe$$ is calculated as:

$$x+(-2)=0$$
$$x=+2$$

Similarly, in $$Cr_2O_3$$, the oxidation state of $$Cr$$ is calculated as

$$2\times x+(-2)\times 3=0$$
$$2x=+6$$
$$x=+3$$

Hence, the correct option is $$D$$
Question 10
1 / -0

$$NaCN$$ is sometimes added in the froth floatation process as a depressant when $$ZnS$$ and $$PbS$$ minerals are expected because:

A
$$ZnS$$ forms soluble complex $${ Na }_{ 2 }\left[ Zn{ \left( CN \right) }_{ 4 } \right] $$ while $$PbS$$ form froth

B
$$Pb{ \left( CN \right) }_{ 2 }$$ is precipitated while no effect on $$ZnS$$ form froth

C
$$PbS$$ forms soluble complex $${ Na }_{ 2 }\left[ Zn{ \left( Pb \right) }_{ 4 } \right] $$ while $$ZnS$$ form froth

D
$$NaCN$$ is never added in froth floatation process

Solution

$$NaCN$$ is used as a depressant in the separation and concentration of $$ZnS$$ and $$PbS$$ ore. Here, $$NaCN$$ acts as a depressant for $$ZnS$$ but does not prevent $$PbS$$ from forming the froth.

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Re-Attempt Weekly Quiz Competition

General Principles and Processes of Isolation of Elements Test - 37

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General Principles and Processes of Isolation of Elements Test - 37

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Question 1

Below $$710^{\circ}C$$, $$C$$ is better reducing agent than $$CO$$

Below $$710^{\circ}C$$, $$CO$$ is better reducing agent than $$C$$

Below $$710^{\circ}C, CO$$ is an oxidising agent

Below $$710^{\circ}C, CO_{2}$$ is a reducing agent

Solution

Question 2

attracted towards water

water repellant

lighter

heavier

Solution

Question 3

bayer's process

decomposition

cyanide process

hall's process

Solution

Question 4

froth floatation

gravity separation

froth separation

gravity floatation

Solution

Question 5

native

combined

original

liquid

Solution

Question 6

$${ N }_{ 2 },{ H }_{ 2 }O$$ and $${ Cr }_{ 2 }{ O }_{ 3 }$$

$${ N }_{ 2 },N{ H }_{ 3 }$$ and $$CrO$$

$${ \left( N{ H }_{ 4 } \right) }_{ 2 }Cr{ O }_{ 4 }$$ and $${ H }_{ 2 }O$$

$${ N }_{ 2 },{ H }_{ 2 }O$$ and $$Cr{ O }_{ 3 }$$

$${ N }_{ 2 },{ H }_{ 2 }O$$ and $$CrO$$

Solution

Question 7

Electrolytic refining

Zone refining

The van-Arkel method

Mond process

Solution

Question 8

Malachite

Haematite

Chalcopyrite

Zinc blende

Solution

Question 9

+3, +2

+3, +6

+2, +6

+2, +3

Solution

Question 10

$$ZnS$$ forms soluble complex $${ Na }_{ 2 }\left[ Zn{ \left( CN \right) }_{ 4 } \right] $$ while $$PbS$$ form froth

$$Pb{ \left( CN \right) }_{ 2 }$$ is precipitated while no effect on $$ZnS$$ form froth

$$PbS$$ forms soluble complex $${ Na }_{ 2 }\left[ Zn{ \left( Pb \right) }_{ 4 } \right] $$ while $$ZnS$$ form froth

$$NaCN$$ is never added in froth floatation process

Solution

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