Tag: chemistry

Questions Related to chemistry

What is electrolysis$?$

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

  1. Decomposition of substance by passing electricity

  2. Decomposition of substance by heating

  3. Decomposition of substance by redox reaction

  4. Addition of hydrogen

Show answer
Correct Option: A
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 $A$

What is concentration of ore?

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

  1. Increasing the concentration of metal

  2. Reducing the concentration of metal

  3. Reducing hydrogen ions

  4. Both $A$ and $C$

Show answer
Correct Option: A
Explanation:

Different processes applied in order to increase the percentage of metal in the ore is called concentration of ore.

Define roasting.

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

  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

Show answer
Correct Option: A
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.

Ores in the form of sulphide and carbonate are converted into:

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

  1. water

  2. oxides

  3. aldehyde

  4. alcohol

Show answer
Correct Option: B
Explanation:

It is easy to obtain metals from their oxides. So, ores found in the form of sulphide and carbonates are first converted to their oxides by the process of roasting and calcination.

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

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

  1. liquation

  2. polling

  3. oxidation

  4. distillation

Show answer
Correct Option: D
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. 

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

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

  1. Cryolite

  2. Fluorspar

  3. Pure alumina

  4. All of the above

Show answer
Correct Option: D
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 $D$.

During calcination:

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

  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

Show answer
Correct Option: A
Explanation:

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

Metal oxide can be reduced by __________.

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

  1. $Fe$

  2. $Sn$

  3. $C$

  4. All of these

Show answer
Correct Option: C
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.

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

Usually refractory metals are used in construction of furances because:

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

  1. they are chemically inert

  2. their melting point is high

  3. they can withstand high temperature

  4. none of the above

Show answer
Correct Option: A,C
Explanation:

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

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:

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

  1. auto-reduction

  2. catalytic- reduction

  3. acid reduction

  4. none of these

Show answer
Correct Option: A
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.