CHEMISTRY PAPER 2 - 2019 KCSE Prediction Questions Set 2

INSTRUCTIONS

• Answer ALL questions 
• All working MUST be clearly shown where necessary
• Mathematical tables and silent non- programmable electronic calculators may be used.
• Candidates must answer all the questions in English.

1. Use the grid below to answer questions that follow. Letters do not represent the actual symbols of the elements
   
   
   1. What family name is given to elements G and H     (1mk)
   2. State and explain the difference in reactivity between
      1. G and J         (1mk)
      2. N and P         (1mk)
   3. How does the atomic radius of K compare to that of L. Explain       (2mks)
   4. Element R forms an oxide of the formula RO₂ and belongs to period 2. Indicate on the grid the position of R. (1mk)
   5. Explain the trend in melting points in the group of elements to which I and J belong (2mks)
   6. Write down the formula of the compound formed between K and P                   (1mk)
   7. Name the type of bond formed when F reacts with D. Explain   (2mks)
   8. Give one use of element Q.                                       (1mk)
   9. Write down the electronic arrangement of ion of:-      (2mks)
      H =    
      N =
2.  
   1. Use the set up below to answer the questions that follow
      
      
      1. Write the equation for the reaction in the flask A                             (1mk)
      2. Give the purpose of concentrated sulphuric (VI) acid in the set up      (1mk)
      3. Name another substance which can be used instead of concentrated sulphuric (VI)acid   (1mk)
      4. Write an equation for the reaction taking place in the combustion tube           (1mk)
      5. What property of carbon is being investigated by the reaction in the combustion tube (1mk)
      6. Why is carbon (ii) oxide gas burned and not allowed to escape into the air      (1mk)
   2. Study the diagram below and answer questions that follow
      
      
      1. Identify the structure        (1mk)
      2. Name the bonds labeled   (2mks)
         K –
         L –
      3. Explain why the allotrope drawn above conducts electricity (2mks)
3.  
   1. Name one natural fibre       (1mk)
   2. State two advantages of synthetic fibre over natural fibre     (2mks)
   3. The flow chart below shows reactions starting with ethanol. Study it and answer the questions that follow
      
      
      1. Apart from fermentation, state another way in which ethanol can be obtained.    (1mk)
      2. Identify the reagent and catalyst used in step II      (1mk)
         Reagent ___________________________
         Catalyst ___________________________
      3. Name compound G      (1mk)
      4. Write down a chemical equation between CH₃COONa and soda lime to form products S and R  (1mk)
      5. State one disadvantage of continuous use of substance the formed in step III         (1mk)
      6. Give the LUPAC name and draw the structure of compound T     (2mks)
      7. Name the homologous series to which T belongs   (1mk)
      8. Name the process in      (1mk)
         Step I _____________________________
         Step IV ____________________________
      9. State one industrial use of the process in Step II       (1mk)
4.  
   1. State the main difference between electrolytic cell and electrochemical cell             (1mk)
   2. The diagram below represents a dry cell with Zinc can and graphite as electrodes. Study it and answer the questions that follow
      
      
      1. Identify the anode and the cathode         (1mk)
         Anode _________________________________
         Cathode ________________________________
      2. Explain why ammonium chloride is in paste form and not in solid form    (1mk)
      3. Write an ionic equation at the cathode     (1mk)
      4. Explain why Manganese (IV) oxide is used in the cell     (1mk)
   3. The diagram below shows an arrangement used in electrolysis of dilute sodium chloride solution using inert electrodes and collect gaseous products. Study it and answer question that follow.
      
      
      1. Write the half equations for the reaction at the    (1mk)
         Cathode ___________________
         Anode _____________________
      2. Explain why the volume of gas X is larger than that of gas Y                               (2mks)
      3. If Brine is used in place of dilute sodium chloride a different gas is produced at the anode. Name the gas produced. Explain.  (2mks)
      4. State two factors that may influence the products at the electrode during electrolysis   (1mk)
   4. In an electrolysis of  molten Aluminium oxide, a current of 200 amperes was passed for 48 minutes.  Determine the volume of oxygen gas produced at STP during the electrolysis (IF = 96500c,  volume of the gas at STP = 22.4dm³).    (3mks)
5. Study the information in the table below and use it to answer the question that follow
   

   Mass of a catalyst per 5g of KClO3 in (g)	Time required to produce maximum volume of oxygen gas in (min)	1/t (min-1)
   0.00	8
   0.10	6
   0.20	5
   0.40	4
   0.75	3
   1.00	2.5

   1. Complete the table  (2mks)
   2. On the grid provided, draw a graph of 1/t against the mass of catalyst used (3mks)
      
   3. What conclusion can you draw from the graph        (1mk)
   4. How would the rate of evolution of oxygen alter if granular manganese (iv) oxide was used instead of powdered manganese (iv) oxide. Explain   (2mks)
   5. Calculate the total volume of oxygen gas evolved when 5g of Pottasium chlorate is decomposed completely (K = 39, Cl = 35.5, O = 16  one mole of gas at RTP = 24.0dm³.   (3mks)
6. Study the diagram below and use it to answer questions that follow
   
   
   1. Write an equation for the reaction taking place when the candle burns        (1mk)
   2. What general name is given to compounds made up of  the same elements as the candle  (1mk)
   3. What is the purpose of ice cold water       (1mk)
   4. State one observation made in test tube B when all the burning candle is used up. Explain with the help of equations (3mks)
   5. Describe how you can test the purity of liquid M       (2mks)
7. The scheme below shows the main stages in the extraction of copper metal.
   
   
   1. Name  ores from which copper is extracted      (1mrk)
   2. Identify     
      1. liquid x   (2mrks)
      2. gas G
   3. Explain how x is separated from iron (ii) silicate(FeSiO₃)       (1mrk)
   4. Write an equation for the reaction taking place at chamber B        (1mrk)
   5. Name one environmental hazard associated with the extraction of copper        (1 mrk)
   6. Using relevant equations describe how copper is purified          (2mrks)
   7. Give two uses of copper