An element X has isotopes relative percentage abundance of each isotope. (3mks)
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Electrical kettles used for boiling hard water are normally covered with lime scale.
a) What is responsible for this type of hardness. (1mk)
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b) Why is it possible to remove lime scale with a solution of ethanoic acid? (1mk)
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The table below shows ammeter readings when two acids of the same concentration were used.

Explain the difference in the ammeter readings. (2mks)
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Name the following organic compounds. (2mks)

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A balloon can hold 1000cm3 of air before it bursts. The balloon contains 980cm3 of air at 70c.
Find out whether the balloon bursts when it is taken into a room at 270c. Assuming the pressure of
the gas remains the same. (3mks)
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Study the table below and answer the questions that follow.

a) Which is the most stable isotope? Explain (2mks)
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In the preparation of hydrogen gas using and dilute sulphuric (VI) acid hydrated copper (II)
Sulphate is used as a catalyst.
a) Explain why it is not a suitable catalyst? (1mk)
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b) State the observation in the cause of the reaction. (1mk)
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i) A colourless liquid was suspected to be water. Describe one chemical test you would use to
identify it. (2mks)

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ii) Sea water boils at a range of temperatures above 1000c. Explain (1mk)
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Copper (II) oxide has no effect on litmus papers yet it is basic. Explain (1mk)
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200cm³ of portions of distilled water were heated for 5 minutes in flask A and B. The volume of water in flask A was less than that in flask B.
a) State the type of flame used to heat water in flask B. (1mk)
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b) What other observation would be made in flask B? Explain (2mks)
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Use the compounds M,N, Q and P to answer the questions below.

Give the reagents and conditions used to convert.
a) M to N ( 1½mks)
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b) Q to P ( 1 ½ mks)
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A mixture of magnesium and copper powder was reacted with dilute hydrochloric acid followed by filtration.

a) Name
i) The residue (1mk)
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ii) The filtrate (1mk)
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b) Write an ionic equation for the reaction that took place (1mk)
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The table below gives information of some elements. The letters do not represent actual symbols of elements.

a) Which of the elements is the strongest reducing agent? (1mk)
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b) Explain the difference in the atomic and ionic radius of element X. (2mks)
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c) Write the formula of the compound formed when X reacts with Z. (1mk)
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. Both molten lead (II) bromide and mercury allow an electric current to pass through. Give two differences between their conductivities. (2mks)
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Describe how a solid sample of copper (II) sulphate crystals can be prepared starting with copper metal. (3mks)
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State one advantage of soapless detergents over soapy detergents. (1mk)
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Iron window frames corrode quickly unless carefully protected but Aluminium window frames are resistant to corrosion.
i) Why does Aluminium not corrode as quickly as iron? (1mk)
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ii) Explain why galvanized iron is resistant to corrosion even when the protective surface of zinc is broken. (2mks)
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In the manufacture of sodium carbonate by the solvay process, Ammonia and carbon (IV) oxide, are recycled. Give two advantages of industrial recycling of materials. (2mks)
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In an experiment, 8.0g of anhydrous copper (II) Sulphate were dissolved in 500cm³ of water in a lagged beaker. The temperature of water was 27.00c and that of the solution 28.50c. Calculate the molar heat of solution of anhydrous copper (II) sulphate (Specific heat capacity of solution=4.2Jg^-

Describe the chemical test which can be used to distinguish between nitrogen (I) Oxide and nitrogen (II) oxide. (3mks)
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5.0g of calcium carbonate were reacted with 25.0cm3 of 1.0M hydrochloric acid until there was no further reaction. Calculate the mass of unreacted calcium carbonate. (Ca=40, O=16,C=12,H=1) (3mks)
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The set-up below was used to prepare substance K.

3 marks