Tag: chemistry

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

What is electrolysis$?$

  1. Decomposition of substance by passing electricity

  2. Decomposition of substance by heating

  3. Decomposition of substance by redox reaction

  4. Addition of hydrogen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Electrolysis is the process of decomposition of a substance by passing electricity through it in a molten or dissolved state. 

For example, Electrolysis of fused magnesium chloride gives magnesium at cathode and chlorine at the anode.

Hence, the correct option is $A$

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

Define roasting.

  1. Heating of sulphide ores in the presence of excess air to convert them into oxides

  2. Heating of carbonate ores in the limited supply of air to convert them into oxides

  3. Heating of oxides of metals to turn them into metal

  4. Heating of carbonate ores in the limited supply of air to convert them into sulphide
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ores found in the form of sulphide and carbonates are first converted to their oxides by the process of roasting and calcination. Heating of sulphide ores in the presence of excess air to convert them into oxides is known as roasting.

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

Mercury has low boiling point. Therefore it can be purified by the process of:

  1. liquation

  2. polling

  3. oxidation

  4. distillation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mercury has a low boiling point. Therefore it can be purified by the process of distillation because then mercury will evaporate and collected in pure form and impurities will remain back. 

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

During electrolytic refining of Alumina, the molten electrolyte used contains _______ .

  1. Cryolite

  2. Fluorspar

  3. Pure alumina

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During electrolytic refining of Alumina, the molten electrolyte used contains pure alumina $(Al _2O _3)$. The electrolyte consists of alumina dissolved in fused Cryolite (Na$ _3$AlF$ _6$) and Fluorspar(CaF$ _2$).


Hence, the correct option is $D$.

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

During calcination:

  1. carbonate ores are changed into oixdes

  2. oxide ores are changed into carbonates

  3. carbonate ores are changed into sulhides

  4. oxide ores are changed into sulphides
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

During calcination, carbonate ores are changed into oxides by heating strongly in limited air.
$ZnCO _3 \rightarrow ZnO + CO _2$

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

Metal oxide can be reduced by __________.

  1. $Fe$
  2. $Sn$
  3. $C$

  4. All of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Metal oxide of the low reactivity can be reduced by carbon in the simple extraction process. For example; lead oxide is reduced by carbon and it extract lead from its ore.

$2PbO(l) + C(s)  \rightarrow 2Pb (s) + CO _2 (g)$

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

Usually refractory metals are used in construction of furances because:

  1. they are chemically inert

  2. their melting point is high

  3. they can withstand high temperature

  4. none of the above
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

The walls of a furnace should not react with metals or ore. So retractory metals are used as they are chemically inert.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore
Given below are the steps for extraction of copper from its ore. The balance reaction involved in reduction of copper(I) oxide with copper(I) sulphide is given in the reaction below.

      $2Cu _{2}O + Cu _{2}S \xrightarrow{Heat} 6Cu + SO _{2}$. 

This reaction is known as:

  1. auto-reduction

  2. catalytic- reduction

  3. acid reduction

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Auto-reduction is a process in which sulphide ores of less electropositive metals like Hg, Pb, Cu etc., are heated in air so as to convert part of the ore into oxide or sulphate which then reacts with the remaining of sulphide ore in absence of air to give the metal and sulphur dioxide.