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year 10 chemistry mid-term exams for IGCSE CAMBRIDGE

1.  Carbon and silicon are elements in Group IV. Both elements have macromolecular structures. (a) Diamond and graphite are two forms of the element carbon.

(i) Explain why diamond is a very hard substance.

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 (ii) Give one use of diamond.

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2. There are three types of giant structure – ionic, metallic and macromolecular.

(a) Sodium nitride is an ionic compound. Draw a diagram that shows the formula of the compound, the charges on the ions and the arrangement of the valency electrons around the negative ion. Use x to represent an electron from a sodium atom. Use o to represent an electron from a nitrogen atom.

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(b) Describe metallic bonding. [3]

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(ii) Use the above ideas to explain why metals are:-

a.  good conductors of electricity, [1]

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(b). metals are malleable. [2]

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(c). Silicon (IV) oxide has a macromolecular structure. [1]

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 (i). Describe the structure of silicon(IV) oxide (a diagram is not acceptable). [3]

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(ii) Diamond has a similar structure and consequently similar properties. Give two physical properties common to both diamond and silicon(IV) oxide. [2]

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(iii) State any 1 use of silicon (IV) Oxide.  [1]

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iv) silicon (IV)Oxide  does not conduct electricity. State an explanation for this. [1]

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6. Convert the following:-     [C=12, N=14, H=1,K=39, L=6.023X1023]

1. 7 grams of carbon to moles                                                            [1]

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2. 12 grams of K3N to Avogadro’s number of particles                      [1] ………………………………………………………………………………………………………………………………………………………………………………………………………..

3. 0.7 moles of C3H8 to mass                                                             [2] ……………………………………………………………………………………………………………………………………………………………………………………………………….…………………………………………………………………………………………………………………………………………………………………………………………………………….

7. 17 tonnes of impure sample of bauxite [ore for aluminium oxide] was extracted by electrolysis to produce 2tonnes of aluminium oxide. Calculate the percentage purity of the ore. [2]

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8. 16g of Magnesium chloride reacts with  excess sodium carbonate to form magnesium carbonate as shown below

 MgCl2  + Na2CO3                                        MgCO3   +   NaCl

1. Balance the equation above.   [1]

2. Calculate the moles of magnesium chloride used in the reaction. [2]

…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………………3. Use the mole ratio to determine the moles of MgCO3 that was formed. [2]

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4. Determine the mass of MgCO3 formed. [1]

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9.  balance the following chemical equations    [12]

1.   N2 + O2                                                  NO2  

2. K2CO3 +  HCl                                         KCl  +    CO2    +   H2O

3. C3H8  +     O2                                 CO2+     H2O

4.  Ca(OH)2  +   HCl                          CaCl2 +     H2O

5. Al +    HCl                           AlCl3  + H2O

10. Draw the following compounds to show how they are bonded. [10]

Methanol [CH3OH]

Carbon Dioxide [CO2]

Ethene  [C2H4]

Magnesium Chloride [MgCL2]

Sodium Oxide [Na2O]

Give one property of ionic compounds.

………………………………………………………………………………………….. [1]