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Explain how you would obtain solid sodium carbonate from a mixture of lead carbonate and sodium carbonate powders.
Date posted:
February 2, 2017
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Describe how the following reagents can be used to prepare lead sulphate. Solid potassium sulphate, solid lead carbonate, dilute nitric (V) acid and distilled water.
Date posted:
February 2, 2017
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Yellow phosphorous reacts with chlorine gas to form a yellow liquid. The liquid fumes when exposed to air. Explain these observations.
Date posted:
February 2, 2017
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Explain why Phosphorous is stored under water
Date posted:
February 2, 2017
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Explain why anhydrous aluminium chloride is fairly soluble in organic solvent while anhydrous magnesium chloride is insoluble.
Date posted:
February 2, 2017
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A crystal of iodine, heated gently in a test gave off a purple vapour.
a) Write the formula of the substance responsible for the purple vapour
b) What type of bond is broken when the iodine crystal is heated gently
c) state one use of iodine
Date posted:
February 2, 2017
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In terms of structure and bonding, explain the following observations
a) The melting point of aluminium is higher than that of sodium:
b) Melting point of chlorine is lower than that of sulphur
Date posted:
February 2, 2017
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In terms of structure and bonding, explain why the melting point of oxygen is much lower than that of sodium.
Date posted:
February 2, 2017
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Distinguish between a covalent bond and co-ordinate bond.
Date posted:
February 2, 2017
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The atomic numbers of elements C and D are 19 and 9 respectively. State and explain the electrical conductivity of the compound CD in
a) Solid state
b) Aqueous state
Date posted:
February 2, 2017
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With reference to iodine, distinguish between covalent bonds and Van Der Waals forces.
Date posted:
February 2, 2017
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Oxygen and sulphur belong to group (VI) of the periodic table. Explain why there is a big difference in their melting points (melting points of oxygen is -216oC) while that of sulphur is 44oC
Date posted:
February 2, 2017
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The melting point of phosphorus trichloride is - 91oC while that of magnesium chloride is 715oC. In terms of structure and bonding, explain the difference in their melting points
Date posted:
February 2, 2017
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Compound Q is a solid with a giant ionic structure. In what forms would be compound conduct an electric current?
Date posted:
February 2, 2017
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Diamond and graphite are allotropes of carbon. In terms of structure and bonding explain the following:
i) Diamond is used in drilling through hard rocks
ii) Graphite is used as a lubricant
Date posted:
February 2, 2017
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Explain why the reactivity of group (VII) elements decreases down the group.
Date posted:
February 2, 2017
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An atom of hydrogen can form two ions. Write two equations to show how a neutral atom of hydrogen can form two ions. In each case show the sign of energy change involved.
Date posted:
February 2, 2017
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Name one property of neon that makes it possible to be used in electric lamps.
Date posted:
February 2, 2017
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Give two reasons why helium is used in weather balloons.
Date posted:
February 2, 2017
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Write the formula of sulphide of an element C, whose atomic number is 5. C is not the actual symbol of the element.
Date posted:
February 2, 2017
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An element Y has the electronic configuration 2.8.5
a) which period of the periodic table does the element belong
b) Write a formula of the most stable anion formed when element Y ionises
c) Explain the difference between the atomic radius of element Y and its ionic radius
Date posted:
February 2, 2017
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The atomic numbers of phosphorus, sulphur and potassium are 15, 16 and 19 respectively. The formulae of their ions are P3-, S2- and K+. These ions have the same number of electrons
i) Write the electron arrangement of the ions
ii) Arrange the ions in the increasing ionic radius starting with the smallest. Give a reason for the order
Date posted:
February 2, 2017
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Why is calcium more reactive than beryllium?
Date posted:
February 2, 2017
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Write the electronic configuration of calcium (atomic number 20) and beryllium (atomic number 4).
Date posted:
February 2, 2017
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With reference to atomic number of one, explain why hydrogen can be placed in either group I and VII of the periodic table.
Date posted:
February 2, 2017
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The electron arrangement of ions X3+ and Y2- are 2,8 and 2,8,8 respectively
a) Write the electronic arrangement of the elements X and Y
b) Write the formula of the compound that would be formed between X and Y
Date posted:
February 2, 2017
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A candle wax is mainly a compound consisting of two elements. Name the two elements
Date posted:
February 2, 2017
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In an experiment, a piece of magnesium ribbon was cleaned with steel wool. 2.4 g of the clean magnesium ribbon was placed in a crucible and completely burnt in oxygen. After cooling, the product weighed 4.0 g
a) Explain why it was necessary to clean the magnesium ribbon
b) What observation was made in the magnesium ribbon
c) Why was there an increase in mass
Date posted:
February 2, 2017
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When wood is burnt, a grey powder called ash remains. The ash is stirred with water and filtered a colourless solution is obtained
a) What is the main component of the colourless solution
b) Explain your answer in (a) above
c) State the observation that would be made if methyl orange indicator was passed through the solution of ash.
Date posted:
February 2, 2017
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Name another gas which used together with oxygen in welding
Date posted:
February 2, 2017