• 23 April, 2024

 

 

 

 

 

 

 

 

 

 


FORM TWO PRE- MOCK EXAMINATIONS

CHEMISTRY

GOLDEN SECONDARY SCHOOL – EXTERNAL EXAMINATION


TIME:2:30 HRS

INSTRUCTIONS:

  1. This paper consists of sections A, B and C.
  2. Answer all questions in all questions.
  3. All writing should be in blue or black ink except diagram which must be in pencil.
  4. All communication devices are not allowed in the examination room.
  5. Non programmable calculators are allowed in the examination room.
  6. The following constant may be applied: R.A.M; C = 12, H = 1, O =16, S = 32, Na = 23, Ca =40

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SECTION A (10 Marks)

 

  1. For each of the items (i) – (x) choose the correct answer from the given alternatives and write its letter in the box provided.

 

  1. The part of Bunsen burner that controls the amount of air coming in is called:
    1. Air hole
    2. Barrel
    3. Collar
    4. Jet

       

  2. A ____________ is a container which is made of porcelain and in which substances can be heated to very high temperature.
    1. Wire gauze
    2. Tripod stand
    3. Crucible
    4. Boiling tube

       

  3. Which of the following is nota product produced by the use of chemistry in agriculture?
    1. Fertilizers
    2. Weed killers
    3. Canned food
    4. Animal vaccines

       

  4. Which of the following apparatuses is used for scooping chemicals?
    1. A pair of tongs
    2. Spatula
    3. Test tube holder
    4. Filter funnel

       

  5. An element X with atomic number 16, belongs to:
    1. Period 3, group III, valency of 2
    2. Period 3, group VI, valencyof 2
    3. Period 3, group VI, valency of 6
    4. Period 6, group VI, valency of 6

 

  1. Which of the following is a sequential method of separating mixture of salt and sand?
    1. Evaporation, filtration and decantation.
    2. Decantation, evaporation and filtration.
    3. Sedimentation, evaporation and filtration.
    4. Decantation, filtration and evaporation.

       

  2. what is the oxidation state of chlorine in KClO3
    1. +2
    2. -5
    3. +5
    4. +3

       

  3. __________ is the blockage of the upper part of the airway by food or other objects.
    1. Choking
    2. Suffocation
    3. Shock
    4. Poisoning

       

     

  4. If somebody has the signs of poisoning such as pain, difficulty in breathing, diarrhoea, abdominal cramps or vomiting, we should not:
    1. Call for medical assistance
    2. Find out what caused poisoning as it is not important.
    3. Force him/her to vomit if the poison has been swallowed and it is corrosive.
    4. Apply ointment if the poison is on the skin.

       

  5. Which one comes right after the step 3 (experimentation and observation).
    1. Formulation of hypothesis
    2. Data interpretation
    3. Data collection
    4. Problem identification

       

 

 

SECTION B (Marks 10)

 

  1. You are provided with a two LIST A and B. Choose a word(s) form LIST B which matches the statement or phrase in LIST A and write its letter in the table provided.

     

LIST A

LIST B

  1. Used to scooping small amount of powder or crystals.
  2. Used to separate solid from liquid.
  3. Used to hold hot substance and apparatus.
  4. Used to store different chemicals.
  5. Used to hold substance that are being weighed or observed.
  6. Used to store distilled water.
  7. Used to measure volume of liquid or gases.
  8. Used to heat small amount of substance inside the gas jar.
  9. Used to protect eyes.
  10. Used to accurately time laboratory process.
  1. Beaker
  2. Tongs
  3. Conical flask
  4. Measuring cylinder
  5. Reagent bottle
  6. Thermometer
  7. Stop watch
  8. Measuring syringe
  9. Watch glass
  10. Deflagrating spoon
  11. Separating funnel
  12. Plastic wash bottle
  13. Filter funnel
  14. Spatula
  15. crucible

 

ANSWERS

LIST A

i

ii

iii

iv

v

Vi

vii

viii

ix

X

LIST B

          

 

SECTION C (Marks 80)

 

  1. (a)    Write the symbols of the elements below.                    
    1. Silver: ________________        (ii) Chromium: _____________

    (iii)    Calcium: ______________        (iv) Mercury: _______________

 

(b)    Write the IUPAC names for each of the following compound:

  1. N2 O4__________________________
  2. Fe2O3 __________________________
  3. CuO __________________________
  4. PbO2 __________________________
  5. MnO2__________________________

(c)    Explain three points on the importance of changing one state of matter to another.

  1. _________________________________________________________________________
  2. _________________________________________________________________________
  3. _________________________________________________________________________

     

  1. Study the periodic Table below:

    I    VIII

A

II III IV V VI VII

B

C

 

D

    

E

F

    

G

H

 
 

J

      

 

Use the letters shown in the Periodic Table above to indicate:

  1. Elements with zero valency._______________________________________
  2. The lightest atom.___________________________
  3. The alkaline earth metal.______________________
  4. An element with an electronic configuration of 2:8:1._________________________
  5. Give the names of the elements represented by the mentioned letters A,B,C,D and J

    A ________________

    B ________________

    C ________________

    D ________________

    J ________________

  6. Write the electronic configuration of J2+. ___________________________________

     

  1. (a)    In an experiment, two iron nails A and B were used whereby painting was applied on nail A. The two nails were placed in a moist environment and after one month the weight of each nail was determined. Which of the two nails would be heavier? Give reason. ___________________________________________________________________________________

___________________________________________________________________________________

(b)    State the method which will be used to protect each of the following from rusting.

    (i)    Covering iron sheets with a layer of most reactive metals. _____________________________

    (ii)    Bicycle chain. ___________________________________

(c)    Find the oxidation number of the underlined elements in the following:

    (i) MnO4–

 

 

 

 

  1. K2Cr2O7

     

     

     

     

  2. H2O2    

     

     

     

     

  1. (a)    (i) Why may a flame produced by a “spirit lamp” not be good for heating in the laboratory? Give

    two reasons.

    ________________________________________________________________________________________________________________________________________________________________

    1. Name the type of flame produced by a spirit lamp. _______________________________________

    (b)    By using the locally available materials in your school, state how the fire can be extinguished in the following situations:

        (i)    Kerosene spilled on the floor catches fire._____________________________________________

            _______________________________________________________________________________

            _______________________________________________________________________________

    1. Friend’s clothes catch fire which gets out of her control._________________________________

    _______________________________________________________________________________    _______________________________________________________________________________

(c)    State four characteristics of a good fuel                

___________________________________________________________________________________

___________________________________________________________________________________

______________________________________________________________________________________________________________________________________________________________________

 

 

  1. (a) Which method would you use to separate each of the following mixtures?
    1. Water mixed with kerosene

      ____________________________________________________________________________

    2. Iron powder mixed with sand.

      ____________________________________________________________________________

    3. Ammonium chloride crystals mixed with sodium chloride crystals

      ____________________________________________________________________________

    4. Water mixed with alcohol.

      ____________________________________________________________________________

    (b)    Name one function for each of the following laboratory apparatus:

  1. Burette._________________________________________________________________________
  2. Desiccator.______________________________________________________________________
  3. Kipp’s apparatus._________________________________________________________________
  4. Liebig condenser. _________________________________________________________________

     

  1. (a) Draw a well labelled diagram of preparation hydrogen gas.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(b) Briefly explain how hydrogen gas is tested in the laboratory.

__________________________________________________________________________________

__________________________________________________________________________________

(c) State any three uses of hydrogen gas.

__________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

 

 

 

  1. (a) What is air?

    __________________________________________________________________________________

    (b) Mention all the components of air with their percentage composition:

    _____________________________________

    _____________________________________

    _____________________________________

    _____________________________________

    (c)Give four reasons why air is said to be a mixture and not a compound.

    __________________________________________________________________________________

    __________________________________________________________________________________

    __________________________________________________________________________________

    __________________________________________________________________________________

     

 

  1. (a) Calculate the percentage composition of the underlined elements in the following compounds:
    1. Na2SO4

       

       

       

       

    2. Ca(HCO3)2

       

       

       

(b) A compound M is composed of 52.2% carbon, 13% hydrogen and the rest is oxygen. If the molecular

of M is 138, calculate:

  1. The empirical formula
  2. The molecular formula

 

 

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