Tag: chemistry

Questions Related to chemistry

Which of the following is a physical mean for concentration of ore?

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. Using sodium hydroxide

  2. Using electrolysis

  3. Froth flotation method

  4. None of above

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Correct Option: C
Explanation:

In many cases, it is possible to separate the metal compound from unwanted rocky material by physical means. A common example of this involves froth flotation. In this method, the unwanted object binds with air and comes on the surface as bubbles.

In electrolytic refining of any metal impure metal is taken as ...............

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. anode

  2. cathode

  3. solution

  4. both B and C

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Correct Option: A
Explanation:

In electrolytic refining, impure metal is of positive charged anode and pure metal is of negative charged cathode.

Heating the ore is in the presence of air is ?

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. roasting

  2. melting

  3. calcination

  4. none of these

Show answer
Correct Option: A
Explanation:

Heating of ore in the presence of oxygen is called roasting. It is a Pyrochemical Process. 

Eg: $2ZnS(s) + 3O _2 (g) \rightarrow 2ZnO (s) + 2SO _2 (g) $
      Zinc Blende 

State the given statement is true or false.
Statement: Mercuric oxide is reduced by thermal decomposition.
chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. True

  2. False

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Correct Option: A
Explanation:
Mercury(II) oxide, a red solid, decomposes when heated to produce mercury and oxygen gas. A reaction is also considered to be a decomposition reaction even when one or more of the products are still compounds. A metal carbonate decomposes into a metal oxide and carbon dioxide gas.

$2HgO(s) \overset{\Delta}\longrightarrow 2Hg(l) + O _2(g)$

Hence, the given statement is $true$.

The order of processes involved in the dressing of an ore are :
(i) grinding and crushing           (ii) hand picking                (iii) pulverization

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. (i), (ii), (iii)

  2. (i), (iii), (ii)

  3. (ii), (iii), (i)

  4. (ii), (i), (iii)

Show answer
Correct Option: D
Explanation:

Dressing of ore can be carried out by first handpicking followed by crushing and grinding and then pulverization.


Hence, the correct option is $(D)$

Identify the oxide ore among the following :

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. Copper pyrites

  2. Copper glance

  3. Siderite

  4. Limonite

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Correct Option: D
Explanation:

Formula of Limonite is $F _eO(OH)\cdot nH _2O$. It is an oxide ore.

The process of carrying out the reduction of metal oxides by heating with coke is termed as :

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. Roasting

  2. Smelting

  3. Zone refining

  4. Ore dressing

Show answer
Correct Option: B
Explanation:

Smelting is the process where heat is applied to ore to extract the base metal, using a reducing agent. So, it is used to carry out reduction of metal oxides to metal by heating with coke.

The above process is:

$HgS\xrightarrow{O _2}HgS.HgO$
                         $\downarrow\Delta$
                        $Hg$ 

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. auto oxidation

  2. self reduction

  3. thermal reduction

  4. none of the above

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Correct Option: B
Explanation:

Cinnabar ($HgS$), when heated with a current of $O _2$ gets reduced to $Hg$ without the need of any additional reducing agent. The process involved is known as self reduction

Which of the following metal oxides are reduced by CO?

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. ZnO

  2. Fe$ _2$O$ _3$

  3. CaO

  4. Al$ _2$O$ _3$

Show answer
Correct Option: A,B
Explanation:

Oxides of highly reactive metals cannot be reduced by $CO$. Hence $CaO$ and $Al _2O _3$ are not reduced by $CO$ and both $ZnO $ and $Fe _2O _3$ are reduced by $CO$

In which of the following chemical leaching is used either in the extraction of metal or in the concentration of ore?

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. Argentite

  2. Bauxite

  3. Alluvial sand containing gold

  4. All of these

Show answer
Correct Option: A