i) Pentane - No observable change
ii) Pentanol - Effervescence producing a gas that burns with a pop sound
johnmulu answered the question on February 21, 2017 at 11:12
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Name one natural fibre and give one advantage of synthetic fibres over natural fibres.
(Solved)
a) Name one natural fibre
b) Give one advantage of synthetic fibres over natural fibres.
Date posted:
February 21, 2017
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Answers (1)
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a) Name the raw material from which sodium is extracted.
b) Give a reason why sodium is extracted using electrolysis
c) Give two reasons of sodium metal
(Solved)
a) Name the raw material from which sodium is extracted.
b) Give a reason why sodium is extracted using electrolysis
c) Give two reasons of sodium metal
Date posted:
February 21, 2017
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Answers (1)
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One of the ores of copper has the formula, CuFeS2.
Describe how iron in the ore is removed during extraction of copper metal.
(Solved)
One of the ores of copper has the formula, CuFeS2.
a) Describe how iron in the ore is removed during extraction of copper metal.
b) State two environmental problems associated with extraction of copper metal
Date posted:
February 21, 2017
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Answers (1)
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Aluminium is both malleable and ductile....
(Solved)
Aluminium is both malleable and ductile
a) What is meant by?
i) Malleable
ii) Ductible
b) State one use of alumunium based on:
i) Malleability
ii) Ductility
Date posted:
February 21, 2017
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Answers (1)
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a) Explain why the metals magnesium and aluminium are good conductors of electricity
b) Other than cost, give two reasons why aluminium is used for making electric cables while magnesium is not.
(Solved)
a) Explain why the metals magnesium and aluminium are good conductors of electricity
b) Other than cost, give two reasons why aluminium is used for making electric cables while magnesium is not.
Date posted:
February 21, 2017
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Answers (1)
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In the industrial extraction of lead metal, the ore is first roasted in a furnace.
(Solved)
In the industrial extraction of lead metal, the ore is first roasted in a furnace. The solid mixture obtained is then fed into another furnace together with coke, limestone and scrap iron. State the function of each of the following in this process:
a) Coke
b) Limestone
c) Scrap iron.
Date posted:
February 21, 2017
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Answers (1)
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The basic raw material for extraction of aluminium is bauxite. Name and explain the following........
(Solved)
The basic raw material for extraction of aluminium is bauxite.
a) Name the method that is used to extract aluminium from bauxite
b) Write the chemical formula of the major component of bauxite
c) i) Name two major impurities in bauxite
ii) Explain how the impurities in bauxite are removed
d) cryolite is used in extraction of aluminium from bauxite. State its function
e) Aluminium is a reactive metal yet utensils made of aluminium do not corrode easily. Explain this observation.
Date posted:
February 21, 2017
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Answers (1)
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Brass is an alloy of zinc and copper. Give one use of brass.
(Solved)
Brass is an alloy of zinc and copper. Give one use of brass.
Date posted:
February 21, 2017
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Answers (1)
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Iron is extracted from its ore by the blast furnace process, name one ore from which iron is extracted.
(Solved)
Iron is extracted from its ore by the blast furnace process
a) Name one ore from which iron is extracted.
b) One of the impurities in iron is removed in the form of calcium silicate. Write an equation for the reaction in which calcium silicate is produced.
Date posted:
February 21, 2017
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Answers (1)
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When the oxide of element H was heated with element H was heated with powdered carbon the mixture glowed and carbon (IV) oxide was formed. When the experiment was repeated using the oxide of element J, there was no apparent reaction.
(Solved)
When the oxide of element H was heated with element H was heated with powdered carbon the mixture glowed and carbon (IV) oxide was formed. When the experiment was repeated using the oxide of element J, there was no apparent reaction.
a) Suggest one method that can be used to extract element J from its oxide
b) Arrange the elements H, J and carbon in the order of their decreasing reactivity.
Date posted:
February 21, 2017
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Answers (1)
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Aluminium metal is a good conductor and is used for overhead cables. State any other two properties that make aluminium suitable for this use.
(Solved)
Aluminium metal is a good conductor and is used for overhead cables. State any other two properties that make aluminium suitable for this use.
Date posted:
February 21, 2017
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Answers (1)
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State one advantage and one disadvantage of using petrol containing tetraethyl lead in motor vehicles
(Solved)
Give one advantage and one disadvantage of using petrol containing tetraethyl lead in motor vehicles
Date posted:
February 21, 2017
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Answers (1)
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Explain why the sodium metal is stored under kerosene.
(Solved)
Explain why the sodium metal is stored under kerosene.
Date posted:
February 21, 2017
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Answers (1)
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Explain why it is not advisable to use wood ash for cleaning aluminium utensils
and state the advantage of using duralumin in place of aluminium for manufacture of aeroplane n parts
(Solved)
a) Explain why it is not advisable to use wood ash for cleaning aluminium utensils
b) Duralumin is an alloy of aluminium. What is the advantage of using duralumin in place of aluminium for manufacture of aeroplane parts
Date posted:
February 21, 2017
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Answers (1)
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State three uses of copper
(Solved)
State two uses of copper
Date posted:
February 21, 2017
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Answers (1)
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State two applications of electrolysis
(Solved)
State two applications of electrolysis.
Date posted:
February 20, 2017
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Answers (1)
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Calculate the time in minutes required to deposit 1.184 g of copper if a current of 2 amperes was used. (1 Faraday = 96500 coulombs, Cu = 63.5).
(Solved)
Calculate the time in minutes required to deposit 1.184 g of copper if a current of 2 amperes was used. (1 Faraday = 96500 coulombs, Cu = 63.5).
Date posted:
February 18, 2017
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Answers (1)
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A student electroplated a spoon with copper metal. Write an equation for the process that took place at the cathode.
(Solved)
A student electroplated a spoon with copper metal. Write an equation for the process that took place at the cathode.
Date posted:
February 18, 2017
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Answers (1)
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Hydrogen and oxygen can be obtained by electrolysis of acidified water. Using equations for the reactions at the electrodes, explain why the volume of hydrogen obtained is twice that of oxygen.
(Solved)
Hydrogen and oxygen can be obtained by electrolysis of acidified water. Using equations for the reactions at the electrodes, explain why the volume of hydrogen obtained is twice that of oxygen.
Date posted:
February 18, 2017
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Answers (1)
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State and explain the observations made when a copper rod is placed in a beaker containing silver nitrate solution
(Solved)
State and explain the observations made when a copper rod is placed in a beaker containing silver nitrate solution.
Date posted:
February 16, 2017
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Answers (1)