Tag: chemistry

Questions Related to chemistry

(a) In smelting process carried out in blast furnace for the exgtraction of iron, lower region of the furnace has the highest temperature.
(b) Formation of $CO$ from ${CO} _{2}$ and coke reduces the temperature of the middle region of blase furnace.
(c) Limestone is taken blast furnace as flux.
(d) Silica present in the ore as gangue is converted to fusible slag by the process of reduction
Which of the following regarding the process of smelting is correct?

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. a, b and c

  2. b and c

  3. only a

  4. only d

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Correct Option: A
Explanation:

The extraction of metal in the fused state is termed smelting. The ore is reduced by carbon to the free metal. A hot blast of air (sometimes with oxygen enrichment) is blown into the lower section of the furnace through a series of pipes . Formation of $CO$ from $CO _2$ and coke reduces the temperature of the middle region of blase furnace. Flux is a chemical substance which combines with gangue at higher temperaturesto form easily fusible material called slag which is not soluble in the molten metal. Limestone is taken blast furnace as basic flux. Silica present in the ore as gangue is converted to fusible slag by the process of oxidation  in flux.

The manufacture of iron from iron ore involves the process of :

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. oxidation

  2. reduction

  3. fractional distillation

  4. electrolysis

  5. None of the above

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Correct Option: B

Nitriding is a process of heating steel in atmosphere of:

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. $NH _3$

  2. $N _2$

  3. $O _2$

  4. $CO _2$

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Correct Option: A
Explanation:

Nitriding is the surface hardening process where nitrogen is added to the surface of steel parts using dissociated ammonia as the source. Gas nitriding develops a very hard case in a component at relatively low temperature. It is carried out at temperature below the transformation temperature of alloy steels and parts to be nitrided are heat treated to proper strength level and finally machined.

(a) Thermite welding process exploits the difference in reactivity of different metals.
(b) Zinc spelter is used as cathode in electrolyte refining process of zinc.
(c) Iron is generally refined by electrolytic reduction process
(d) Iron is alloyed with other metals and carbon, only to prevent corrosion.
Which of the following options regarding the above statements is correct?

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. a and d

  2. b and c

  3. only a

  4. a, b and c

Show answer
Correct Option: C
Explanation:

Thermite welding process exploits the difference in reactivity of different metals. Pure zinc rod is used as cathode while a block of impure zinc spelter is used as anode. Iron is generally refined by smelting process.Iron is alloyed with other metals and carbon prevents the oxidation of iron and formation of rust.

The percentage of carbon is the least in :

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. White cast iron

  2. Grey cast iron

  3. Wrought iron

  4. Steel

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Correct Option: D
Explanation:

1: wrought iron carbon content 0.05-0.25%
2 : white and grey iron is the type of cast iron which contain 2.14-6.67% carbon. 
3: steel contain 0.008-2.14% carbon So D. Steel has least Carbon %

Iron reacts with _______.

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. cold water

  2. hot water

  3. water

  4. none of the above

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Correct Option: D
Explanation:

Iron reacts with oxygen and ions to make rust. after rust formation, it does not allow Iron to react with water.

Oven coke is used throughout the world in blast furnaces to make:

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. gold

  2. biomass

  3. iron

  4. all of above

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Correct Option: C
Explanation:

Coke is a fuel with few impurities and a high carbon content, usually made from coal. Oven coke is used throughout the world in blast furnaces to make iron.

The purpose of smelting an ore is to _________ it.

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. oxidise

  2. reduce

  3. neutralise

  4. none of these

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Correct Option: B
Explanation:

Purpose of smelting an ore is to reduce it. $Fe _{2}O _{3}$ is ore and $C$ is reductant.

In smelting, $ Fe _{2}O _{3}+3C\rightarrow 2Fe+3CO$.

Which of the following processes involves the smelting process?

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. $ZnCO _3 \rightarrow ZnO + CO _2$

  2. $2PbS +3O _2 \rightarrow 2PbO + 2SO _2$

  3. $Fe _2O _3 + 3C \rightarrow 2Fe + 3CO$

  4. $Al _2O _3.2H _2O \rightarrow Al _2O _3 + 2H _2O$

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Correct Option: C
Explanation:

In smelting, Iron ore is reduced to iron.

$Fe _{2}O _{3}+3C{\rightarrow}Fe+3CO$

In the extraction of iron, slag is produced which is

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. $CaSiO _3$

  2. $FeSiO _3$

  3. $CO$

  4. $MgSiO _3
    $

Show answer
Correct Option: A
Explanation:
During extraction of iron, soda time is added in furnace because it combines with gangue to form slag
$CaO+SliO _2  \rightarrow CaSiO _3$
Basic        Acidic          Slag