Chemistry Paper 2 Questions and Answers - Bungoma Diocese Mock Exams 2021/2022

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INSTRUCTIONS TO CANDIDATES

  • Answer ALL the questions in the spaces provided in the question paper.
  •  All working MUST be clearly shown where necessary.
  • Mathematical tables and silent electronic calculators may be used.
  1. The grid given below represents part of the periodic table. Study it and answer the questions that follow. The letters are not the actual symbols of the elements.
           Chem BM PP2 Q1 2122
    1. What name is given to the family of elements to which A and C belong? ( 1 mark )
    2. Write the chemical formula of the sulphate of element D. ( 1 mark )
    3. Which letter represents the most reactive ( 2 marks )
      1. Metal
      2. Non-metal
    4. Name the bond formed when B and H react. Explain your answer. ( 2 marks )
    5. Select one element that belong to period 4. ( 1 mark )
    6. Ionic radius of element E is bigger than the atomic radius. Explain. ( 2 marks )
    7. The electron configuration of a divalent anion of element N is 2.8.8. Induce the Position of element N on the periodic table drawn above. ( 1 mark )
    8. The oxide of G has a lower melting point than the oxide of L. Explain. ( 1 mark )
    9. How do the atomic radii of I and C compare. Explain. ( 2 marks )
    10. Explain the trend in the 1st ionization energies of the elements J, I and L.(1mark )
  2.  
    1. define the following terms
      1. Saturated solution(1mk)
      2. Fractional crystallization(1mk)
    2. Solubility of salt X and Y were determined at different temperatures as shown in the following data.
       Temperature (ºC)     0   20   40   60   80   100 
       Solubility of 100g of water    X   12   30   75   125   185   250 
       Y  15  20   30    45    65    80 
      1. On the grid provided, plot a graph of solubility (vertical axis) against temperature. (4mks)
      2. From the graph determine the solubility of each at 50ºC.
        X ……………………………………………………….. (1mk)
        Y ………………………………………………………… (1mk)
      3. At what temperature was the solubility of both salts equal. (1mk)
      4. What is permanent hardness of water? (1mk)
  3. The flow chart below illustrates two industrial processes. Haber and contact processes each with air as one of the starting materials and other chemical reactions.
                Chem BM PP2 Q3 2122
    1.  
      1. Give the name of the process by which air is separated into oxygen and nitrogen. (1 mk)
      2. Apart from oxygen and nitrogen gas produced from process a(i) name any other gas produced in the process above. (1 mk)
    2. Name the substances which are represented by the letter. (4 mks)
      A……………………………..
      B……………………………………..
      C …………………………………….
      D………………………………………
    3. Name the catalyst used in;
      1. The Haber process (1 mk)
      2. The contact process (1 mk)
      3. Explain the role of the catalyst in both the Haber and contact process. (2 mks)
    4.  
      1. Write a balanced equation for formation of compound D. (1 mk)
      2. Calculate the percentage by mass of nitrogen present in compound D
        (N = 14.0, H = 1.0, S = 32.0, O = 16.0) (2 mks)
      3. Give one use of compound D. (1 mk)
  4. A student set-up the arrangement below to prepare and collect dry hydrogen gas
             Chem BM PP2 Q4 2122
    1. Identify two errors from the section of the arrangement shown above (2mks)
    2. Complete the diagram to show how dry hydrogen gas can be collected. (2mks)
    3.  
      1. Explain why hydrogen was collected by the method shown above (1mk)
      2. Write a balanced chemical equation for the reaction that takes place when hydrogen gas is burnt in air. (1mk)
    4. Determine the relative atomic mass of zinc, given that when 6.54g of zinc was used, 2.4litres of hydrogen gas was produced. (Molar gas volume = 24 litres) (3mks)
    5. State any two non-industrial uses of hydrogen gas (2mks)
  5. The diagram below shows an experiment set-up to investigate a property of carbon (ii) oxide. Study it and answer the questions that follow.
                Chem BM PP2 Q5 2122
    1. Name one condition that is missing in the set up that must be present if the experiment to proceed. 1mark
    2. If the experiment was carried out properly. What observation would be made in the combustion tube? 1mark
    3. Give an equation for the reaction that occurs in the combustion tube. 1 mark
    4. Give an equation for the reaction that takes place as gas x burns. 1 marks
    5. Why is it necessary to burn gas x? 1mk
    6. Name the reducing and oxidizing agent. 2marks
      1. Reducing agent
      2. Oxidising agent
    7. Identify any other substance that would have the same effect on copper (ii) oxide as carbon (ii) oxide. 1mark
    8. What would happen if copper (ii) oxide was replaced with sodium oxide? Explain 2mark
  6. Dry chlorine was collected using the set up below.
            Chem BM PP2 Q6 2122
    1. Name a suitable drying agent for chlorine gas? (1mark)
    2. State one property of chlorine gas which facilitates this method of collection. 1mark
    3. State the observations made on the moist blue litmus paper. (2marks)
    4. Chlorine gas was bubbled through distilled water. With aid of an equation show the formation of chlorine water. (1mark)
    5. Write the formula of the compounds formed when chlorine gas reacts with warm dry phosphorous. (2marks)
    6. Chlorine gas is mixed with moist hydrogen sulphide gas, state and explain the observations (2marks)
    7. Give one use of chlorine gas. 1mark
  7. Fractional distillation of air is used in the industrial manufacture of oxygen. The diagram below shows the process.
        Chem BM PP2 Q7 2122
    1. What processes are taking place in chamber A,B,M and D 2marks
    2. Name;
      1. Liquid S(1mk)
      2. Substance T(1mk)
    3. Explain why part Y in chamber D is curved? 1mark
    4. Give two industrial uses of oxygen gas? (2marks)
    5. In the laboratory preparation of oxygen, manganese (iv) oxide and hydrogen peroxide are used. Write an equation to show how oxygen gas is formed. 1mark
    6. An investigation was carried out using the set-up below. Study it and answer the questions that follow.
              Chem BM PP2 Q7f 2122
      1. State and explain what will happen in the three test-tubes R, S and T after seven days. 2marks
      2. Give one reason why some metals are electroplated. 1mark


MARKING SCHEME

  1.  
    1. Noble gases √1
    2. D2SO4 √1
    3.  
      1. Y √1
      2. E √1
    4. Ionic bond √1 – Because B reacts by losing an electron (s) which are gained by H. √1 accept transfer of electrons from a metal to non metal
    5. D//M √1 Any ½ mark each
    6. Because E reacts by gaining an extra electron which reduces √1 the electrostatic pull by the positive nucleus making the ionic radius increase. Or incoming electron causes increased repulsion wtte
    7. At Period III Group IV
    8. Because of the increase in the strength of the molecular bonds in the oxide of L as compared to that of G. √1 w.t.t.e
    9. C has a smaller atomic √1 radius than I because of the increase in the strength of the Nucleur foce of attraction in C as the number of protons increase √1 w.t.t.e
    10. 1st ionization energies increases from J – L across the period due to addition of an extra proton in the nucleus increasing the attraction of the valency electrons √
  2.  
    1.  
      1. A solution that cannot dissolve any more of the solute at that particular temperature. ✔ 1mk
      2. Scientific technique used to separate substances due to their differences in their crystallization temperature. ✔ 1mk or w.t.t.e
    2.  
      1. on the scanned graph
      2. x=100g/100ml, y=40g/100ml
      3. 5°c
      4. type of hardness that cannot be removed by boiling
  3.  
    1.  
      1. Fractional distillation✔ 1mk
      2. Argon//neon/xenon//krypton✔ 1mk
    2.  
      • A Sulphur✔1mk
      • B Ammonia gas✔1mk
      • C sulphur (vi) oxide✔1mk
      • D Ammonium sulphate✔1mk
    3.  
      1. Finely divided iron✔1mk
      2. Vanadium (v) oxide✔1mk
      3. The catalysts fasten✔1mk the Haber & contact processes by lowering the activation energy✔1mk of the reactions//the rate of production is increased.
    4.  
      1. H2SO4(aq) + 2NH3(g) → (NH4)2SO4(aq)✔1mk
      2. Formula mass of (NH4)2SO4 = 2(14+4) + 32 + 4(16)
                                                       = 132grams✔ ½ mk
                                           % of N = 28/132 × 100  ✔1mk
                                                       = 21.212%✔ ½ mk
      3. Use as a fertilizer✔1mk
  4.  
    1.  
      1. The outlet delivery tube should not dip into the Zinc/dilute Sulphuric acid mixture in the round buttoned flask. ✔ 1mk
      2. The use of heat is not required ✔ 1mk
    2.  
      Chem BM PP2 Ans4b 2122
    3.  
      1. It is denser than air ✔1 mk
      2. H2(g) + ½ O2(g) → H2O(g)✔ balancing½ mark  states ½ mark
    4. Zn2(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) balancing ½ mk  states ½ mk
      1vol       1 vol         1vol
      (6.54/R)                    (2.4/24)
      Therefore, (6.54/R) = 2.4/2  ✔1mk   Where R = R.A.M of Zinc
                               R = 24 × 6.54
                                           2.4
                            Or R = 65.4 ✔ 1mk
    5.  
      • H2(g) is used in balloons by meteorologists ✔1mk
      • It is used as rocket fuel ✔ 1mk
  5.  
    1. Heating copper (ii) oxide √1mk
    2. Black solid would turn brown √1mk
    3. CuO(s) + CO(g) → Cu(s) + CO2(g) √1 ½ mk
    4. 2CO(g) + O2(g) → 2CO2(g) √1 ½ mk
    5. It is poisonous √1mk
    6.  
      1. Reducing agent - Carbon(ii) oxide √1mk
      2. Oxidisingagent -Copper (ii) oxide √1mk
    7. Hydrogen / ammonia gas (Any one) √1mk
    8. There would be no observable change √1mk. This is because sodium is higher than carbon in the reactivity series and therefore has higher affinity of oxygen √1mk
  6.  
    1. Concentrated sulphuric (vi) acid √1mk
    2. It is denser than air √1mk
    3.  
      • It turns red then white. √1mk
      • It turns white / it gets bleached √1mk
    4. Cl2(g) + H2O(l) → HOCl(aq) + HCl(aq) √1mk
    5.  
      • PCl3 √1mk
      • PCl5 √1mk
    6.  
      • A yellow deposit of sulphur is formed / seen √1mk
      • Chlorine oxidizes sulphideions to solid sulphur √1mk
    7.  
      • Manufacture of hydrochloric acid √1mk
      • Manufacture of bleaching agents such as chlorate used in the cotton and paper industries
      • Chlorine is used in the treatment of water and sewage plants
      • Manufacture of chloroform as an anaesthetic
      • Manufacture of solvents such as trichloroethane
        Any one
  7.  
    1. A - Filtration √1 ½ mk
      B - Absorption √1 ½ mk
      M - Isolation of water √1 ½ mk
      D - Cooling √1 ½ mk
    2.  
      1. Liquids – NaOH (aq) / KOH (aq) √1mk
      2. Substance T – Ice / water √1mk
    3. To increase surface area forcooling √1 mk
    4.  
      1. Oxygen is used to remove impurities during steel making √1 mk
      2. Is used in cutting and welding of metals √1 mk
    5. 2H2O2(l) MnO2(S) 2H2O(l)+ O2(g) √1 mk
    6.  
      1. R -Rusting occurred √1 ½ mk because of air and water being present √½ mk
        S - No rusting √½ mk Water is absent √½ mk
        T - No rusting √ ½ mk Air is absent √½ mk
      2.  
        • To prevent rusting √1mk
        • To increase aesthetic value of the metal

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