a) Chrorofluorocarbons
b) Harmful rays from the sun will reach the earth causing a lot of harm to humans e.g skin cancer
c) They are green house gases and lead to global warming.
johnmulu answered the question on February 22, 2017 at 04:44
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Some animal and vegetable oils are used to make margarine and soap. Give the reagent and conditions necessary for converting the oils into:
(Solved)
Some animal and vegetable oils are used to make margarine and soap. Give the reagent and conditions necessary for converting the oils into:
a) Margarine
b) Soap.
Date posted:
February 22, 2017
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Answers (1)
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Name the process that takes place when:....
(Solved)
Name the process that takes place when:
i) Crystals of zinc nitrate change into solution when exposed to air
ii) An alcohol reacts with an organic acid in the presence of a catalyst to form a sweet smelling compound.
Date posted:
February 21, 2017
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Answers (1)
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Explain why the boiling point of ethanol is higher than that of hexane
(Solved)
Explain why the boiling point of ethanol is higher than that of hexane (Relative molecular mass of ethanol is 46 while that of hexane is 86)
Date posted:
February 21, 2017
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Answers (1)
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The boiling point of ethanol, propanol and butanol are 78oC, 97.2oC and 117o
(Solved)
The boiling point of ethanol, propanol and butanol are 78oC, 97.2oC and 117oC. Explain this trend
Date posted:
February 21, 2017
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Answers (1)
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Pentane and ethanol are miscible. Describe how water could be used to separate a mixture of pentane and ethanol
(Solved)
Pentane and ethanol are miscible. Describe how water could be used to separate a mixture of pentane and ethanol
Date posted:
February 21, 2017
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Answers (1)
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State the observation that would be made when a piece of sodium metal is placed in samples of:
(Solved)
State the observation that would be made when a piece of sodium metal is placed in samples of:
i) Pentane
ii) Pentanol
Date posted:
February 21, 2017
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Answers (1)
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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)