Selina solutions for Concise Chemistry [English] Class 10 ICSE chapter 7 - Metallurgy [1990 edition]

Name the three classes in which elements are classified. Which was the first metal used by man?

Name the metal present in abundance in the earth's crust.

Name the non-metal present in abundance in the earth's crust.

Name the metal which is a constituent of blood pigment?

Name the metal which is a constituent of plant pigment?

Give the importance of the following for living beings:

Nitrogen

Give the importance of the following for living beings:

Hydrogen

Give the importance of the following for living beings:

Carbon

State the position of the following in the periodic table:

Alkali metals

State the position of the following in the periodic table:

Alkaline earth metals

State the position of the following in the periodic table:

Halogens

State the position of the following in the periodic table:

Aluminium

Name a liquid non-metal.

Name two metalloids.

Name a metal which does not corrode easily.

Name two metals which react with cold water.

Name a non-metal which can form a positive ion.

Name a non-metal which shows reducing property.

From the list of characteristics given below, select the five which are relevant to non-metals and their compounds:

1. Ductile
2. Conduct electricity
3. Brittle
4. Acidic Oxides
5. Basic Oxides
6. Discharged at anode
7. Discharged at cathode
8. Ionic chlorides
9. Covalent chlorides
10. Reaction with dilute sulphuric acid yields hydrogen
11. 1, 2 or 3 valence electrons
12. 5, 6, 7 valence electrons

(Write the five letters corresponding to the correct characteristics).

Why are alkali metals kept in kerosene oil?

Why is hydrogen kept in the metal activity series?

Why do gold ornaments look new even after several years of use? 

From the metals: copper, iron, magnesium, sodium, and zinc, select a different metal in the case which does not react with dilute hydrochloric acid.

From the metals: copper, iron, magnesium, sodium, and zinc, select a different metal in the case which can form 2+ and 3+ ions.

From the metals: copper, iron, magnesium, sodium, and zinc, select a different metal in the case which arranges the above metals in the decreasing order of reactivity.

Which metal occurs as a sulphide also gives the name of their respective ore.

Which metal occurs as a halide also gives the name of their respective ore.

Which metal occurs as a carbonate also gives the name of their respective ore.

Which metal occurs as an oxide also gives the name of their respective ore.

Distinguish between a mineral and an ore.

Distinguish between an ore and a metallic compound.

Which metal can be extracted from the following ore?

bauxite

Which metal can be extracted from the following ore?

Calamine

Which metal can be extracted from the following ore?

Haematite

Explain the following term:

Ore

Explain the following term:

Gangue

Give the principles of the hydrolytic method.

Give the principles of the froth floatation process.

Give the principles of electromagnetic separation.

Name the methods by which concentrated ore is converted to metallic oxide.

State three objectives achieved during the roasting of ores.

Name the processes involved in dressing of the ores.

Name the processes involved in refining of ores.

Name two metallic oxides which cannot be reduced by carbon, carbon monoxide or hydrogen.

Why does iron or zinc not occur free in nature?

What do you observe when hydrogen is passed over heated copper oxide?

What is the difference between calcination and roasting?

Name an ore of zinc.

Which process is applied to concentrate ore of zinc?

How is concentrated ore changed to oxide?

Some metallic oxides can be reduced by hydrogen, carbon and carbon monoxide and some cannot. Explain.

Write a balanced equation for the reduction of copper (ll) oxide by hydrogen.

How is the following metallic oxide reduced? Write equations:

Iron (ll) oxide

How is the following metallic oxide reduced? Write the equation:

Zinc oxide

State why aluminium is extracted from its oxide by electrolysis while copper, lead, iron by reducing agents and mercury and silver by thermal decomposition.

An ore on being heated in air forms sulphurous anhydride. Write the process used for the concentration of this ore.

Define roasting.

Name an ore on which roasting is done. Give a balanced equation.

Define calcination.

Give an example and equation for calcination.

How are metals like sodium, potassium, and calcium obtained? Give equations.

Give the equations for the reduction of copper oxide.

Give the equation for the reduction of Iron (III) oxide.

Give the equations for the reduction of Lead (II) oxide.

Give the equation for the reduction of Zinc oxide.

On which factors does the purification of metals depend?

Name the methods used for purification?

With a labelled diagram, explain the electro-refining of a particular metal.

The metal other than aluminium, which has a strong affinity for oxygen is ______.

A metallic oxide which cannot be reduced by normal reducing agents:

Usually ______ ores are subjected to ______ which is done in the absence of air.

Zinc blende is converted to oxide by ______ process.

Froth floatation process is generally used to concentrate ______ ores.

State the position of aluminium in the periodic table.

Write the chemical formulae of the main ore of aluminium.

Write the chemical formulae of the main ore of iron.

Give the chemical names and formulae of the main ores of zinc.

Which impurities are present in bauxite?

What is red mud, how is it removed?

In order to obtain 1 tonne of aluminium, the following inputs are required: 4 tonnes of bauxite, 150 kg of sodium hydroxide and 600 kg of graphite. The aluminium compound in bauxite is aluminium oxide and the main impurity is iron (III) oxide. Aluminium is obtained by the electrolysis of aluminium oxide dissolved in cryolite.

When bauxite is treated with sodium hydroxide solution, what happens to:

1. the aluminium oxide,
2. the iron (III) oxide?

In order to obtain 1 tonne of aluminium, the following inputs are required: 4 tonnes of bauxite, 150 kg of sodium hydroxide and 600 kg of graphite. The aluminium compound in bauxite is aluminium oxide and the main impurity is iron (III) oxide. Aluminium is obtained by the electrolysis of aluminium oxide dissolved in cryolite.

1. Name the process used for the purification of bauxite.
2. Write the equation for the action of heat on aluminium hydroxide.

In order to obtain 1 tonne of aluminium, the following inputs are required: 4 tonnes of bauxite, 150 kg of sodium hydroxide and 600 kg of graphite. The aluminium compound in bauxite is aluminium oxide and the main impurity is iron (III) oxide. Aluminium is obtained by the electrolysis of aluminium oxide dissolved in cryolite.

1. Write the formula of cryolite.
2. Write down the word which correctly completes the following sentence.
   By dissolving aluminium oxide in cryolite, a ______ (conducting/non-conducting) solution is produced.
3. Why is so much graphite required for the electrolytic process?
4. Write the equation for the reaction which takes place at the cathode.
5. What is cathode made up of?

Aluminium is extracted from its chief ore, bauxite. The ore is first purified and then the metal is extracted from it by electrolytic reduction.

Write three balanced equations for the purification of bauxite.

Name a chemical used for dissolving aluminium oxide. In which state is the chemical used?

Aluminium is extracted from its chief ore, bauxite. The ore is first purified and then the metal is extracted from it by electrolytic reduction.

Write an equation for the reaction which takes place at the anode during the extraction of aluminium by the electrolytic process.

A to F below relate to the source and extraction of either zinc or aluminium.

1. Bauxite
2. Coke
3. Cryolite
4. Froth floatation
5. Sodium hydroxide solution
6. Zinc blende

Write down the three letters each from the above list which are relevant to:

1. Zinc
2. Aluminium

A to F below relate to the source and extraction of either zinc or aluminium.

1. Bauxite
2. Coke
3. Cryolite
4. Froth floatation
5. Sodium hydroxide solution
6. Zinc blende

Fill in the blanks using the most appropriate words from A to F:

(i) The ore from which aluminium is extracted must be treated with ______ so that pure aluminium oxide can be obtained.

(ii) Pure aluminium oxide is dissolved in ______ to make a conducting solution.

A to F below relate to the source and extraction of either zinc or aluminium.

1. Bauxite
2. Coke
3. Cryolite
4. Froth floatation
5. Sodium hydroxide solution
6. Zinc blende

Write the formula of cryolite.

Explain with reason: 

In the electrolytic reduction of alumina, the graphite anode is gradually consumed.

Explain with reason:

Roasting is carried out on sulphide ores and not on carbonate ores.

Explain with reason:

Carbon can reduce lead oxide but not aluminium oxide.

Explain with reason:

Electrolytic reduction is done to obtain aluminium?

Explain the reason:

Why 'food containing iron salts' should not be cooked in aluminium utensils?

Explain with reason:

A neutral gas other than oxygen is formed at the anode during the electrolysis of fused alumina.

Explain with reason:

Why is powdered coke sprinkled on top of the electrolyte?

For bauxite, explain its significance in the extraction of aluminium.

For sodium hydroxide, explain its significance in the extraction of aluminium.

For cryolite, explain its significance in the extraction of aluminium.

For graphite, explain its significance in the extraction of aluminium.

Distinguish between electrolytic methods of reduction and refining.

Give three ways in which the metal zinc differs from the non-metals carbon. At least one of the differences must be a chemical difference?

Aluminium is a more active metal than iron, but suffers less corrosion. Why?

Explain and give reasons why aluminium vessels should not be cleaned with powders containing alkalis.

During the concentration of bauxite ore, aluminium goes in ______ part because of its ______ nature.

In Hoope's process, pure aluminium is collected at the ______ of the electrolytic cell.

Explain the following:

Zinc is used to cover iron so as to prevent rusting of iron. Why?

Explain the following:

In construction work, why is the alloy of aluminium-duralumin used rather than pure aluminium?

What is an alloy?

How do the properties of an alloy differ from alloy constituents?

Both brass and bronze contain copper as major constituents. Name other elements in these alloys.

Name an alloy of aluminium used in aircraft construction.

Name an alloy of lead used in electrical wiring or electrical work in joining metals.

Name an alloy of copper in electrical appliances or household vessels.

Name an alloy of zinc used in naval ships.

What is an amalgam?

State amalgam use with an example.

State two properties of brass that render it more useful for some purpose than its components.

Name a metal which forms a liquid alloy at ordinary temperature.

Name the constituents of Duralumin.

Name the constituents of Solder.

Name the constituents of Bronze.

Name the constituents of Brass.

Name the following:
or

With reference to the physical properties of metals and non-metals, state the following exception.

A metal which is liquid at room temperature.

Name the following:

A metal which is always present in the amalgam.

Name the following:

The process of heating an ore to a high temperature in the presence of air.

Name the following:

The compound formed by the reaction between calcium oxide and silica.

Name the following:

A compound which is added to lower the fusion temperature of the electrolytic bath in the extraction of aluminium.

Name the following:

Name an allotrope of a non-metal that allows electricity to pass through it.

Brass is an alloy of ______.

Steel is an alloy of iron and ______.

The reason for using Aluminium in the alloy duralumin is ______.

Name the alloy used for the following purpose.

Making electric circuits

Name the alloy used for the following purpose.

Making medals

Name the alloy used for the following purpose.

Making parts of watches

Name the alloy used for the following purpose.

Surgical instruments

Name the alloy used for the following purpose.

Aircraft

The following is an extract from 'Metals in the Service of Man, Alexander and Street/Pelican 1976':

1. Which solution is used to react with bauxite as a first step in obtaining pure aluminium oxide?
2. The aluminium oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide. Write the balanced chemical equation for this reaction.
3. Name the element which serves both as the anode and the cathode in the extraction of aluminium.
4. Write the balanced chemical equation for the reaction that occurs at the cathode during the extraction of aluminium by electrolysis.
5. Give the balanced chemical equation for the reaction which occurs at the anode when aluminium is purified by electrolysis.

The following is a sketch of an electrolytic cell used in the extraction of aluminium:

1. What is the substance of which the electrodes A and B are made?
2. At which electrode (A or B) is aluminium formed?
3. What are the two aluminium compounds in the electrolyte C?
4. Why is it necessary for electrode B to be continuously replaced?
   

State the property of the metal being utilized in the following :

Name a metal which is found abundantly in the Earth's crust.

What is the difference between calcination and roasting?

Name the process used for the enrichment of sulphide ore.

Write the chemical formulae of the main ore of iron.

Write the chemical formulae of the main ore of aluminium.

Write the constituents of the electrolyte for the extraction of aluminium.

Name the following metal:

A metal present in cryolite other than sodium.

Name the following metal:

A metal which is unaffected by dilute or concentrated acids.

Name the following metal:

A metal present in period 3, group 1 of the periodic table.

The following questions are relevant to the extraction of Aluminium:

1. State the reason for the addition of caustic alkali to bauxite ore during the purification of bauxite.
2. Give a balanced chemical equation for the above reaction.
3. Along with cryolite and alumina, another substance is added to the electrolyte mixture. Name the substance and give one reason for the addition.

Using the information above, complete the following:

1. _________ is the metallic element.
2. Metal atoms tend to have a maximum of ________ electrons in the outermost energy level.
3. Non-metallic elements tend to form _________ oxides while metals tend to form _______ oxides.
4. Non-metallic elements tend to be ______ conductors of heat and electricity.
5. Metals tend to _______ electrons and act as ________ agents in their reactions with elements and compounds.

The main ore used for the extraction of iron is ______.

Heating an ore in a limited supply of air or in the absence of air at a temperature just below its melting point is known as ______.

State the main components of the following alloy:

Brass

State the main components of the following alloy:

Duralumin

State the main components of the following alloy:

Bronze

Name the following:

The property possessed by metals by which they can be beaten into sheets.

Name the following:

A compound which is added to lower the fusion temperature of the electrolytic bath in the extraction of aluminium.

Name the following:

The ore of zinc containing its sulphide.

Choose the most appropriate answer from the following list of oxides which fit the description.

A basic oxide.

Choose the most appropriate answer from the following list of oxides which fit the description.

An oxide which dissolves in water forming an acid.

Choose the most appropriate answer from the following list of oxides which fit the description.

An amphoteric oxide.

Choose the most appropriate answer from the following list of oxides which fit the description.

A covalent oxide of a metalloid.

For the substance given below, describe the role played in the extraction of aluminium.

Cryolite

For the substance given below, describe the role played in the extraction of aluminium.

Sodium hydroxide

For the substance given below, describe the role played in the extraction of aluminium.

Graphite

Name the solution used to react with bauxite as a first step in obtaining pure aluminium oxide, in the Baeyer's process.

Write the equation for the reaction where the aluminium oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide.

Name the compound added to pure alumina to lower the fusion temperature during the electrolytic reduction of alumina.

Write the equation for the reaction that occurs at the cathode during the extraction by aluminium by electrolysis.

Explain why it is preferably to use a number of graphite electrodes as anode instead of a single electrode, during the above electrolysis.