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KCSE CHEMISTRY 2020 PREDICTION PAPERS
Kenya Certificate of Secondary Education (K.C.S.E.)
Chemistry Paper 1,2, &3
PREDICTION 1
PAPER 1
1. An element K has atomic number 20 while element M has atomic number 8.
a) Write the electronic configuration for K and M 2marks
b) Write the symbol of the most stable ion of K and M 2mks
2. Molten Lead (II) bromide is electrolyzed using carbon electrodes. Write the half
equations of the reactions that occur at the anode and the cathode.
a) Anode 1mark
b) Cathode 1mark
3. Explain why the conductivity of metals decreases with increase in temperature.2mks
4. Three metal oxides XO, YO, and ZO are heated with powdered metal Y. Hot
powdered Y will remove oxygen from XO but not from ZO. Arrange the metals in
order of reactivity, starting with the most reactive.
1mark
5. Some sodium chloride was found to be contaminated with copper (II) oxide. Describe
how a sample of sodium chloride can be separated from the mixture. 2marks
6. Hot platinum wire was lowered into a flask containing concentrated ammonia solution
as shown below.
Glass rod
Hot platinum wire
Concentrated Ammonia Solution
State and explain the observations made. 3marks
7. The set up below represents the apparatus that may be used to separate a mixture of
two miscible liquids C and D whose boiling points are 800C and 1100C.
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a) Name B 1mark
b) What is the purpose of the thermometer 1mark
c) Which liquid was collected in the test tube? 1mark
8. Draw a dot (.) and cross (x) diagram to show bonding in carbon (II) oxide.
2marks
9. Ammonium nitrate was gently heated and the products collected as shown in the
diagram.
a) Identify:
i. Colourless liquid H 1mark
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ii. Gas G 1mark
b) Describe one physical and one chemical test that can be used to identify gas G.
2marks
10. Air was passed through several reagents as shown in the flow chart below.
Escaping gases
Concentrated Excess heated Excess heated
Air KOH solution copper turnings magnesium
powder
a) What is the purpose of concentrated potassium hydroxide solution? 1mark
b) Write an equation for the reaction which takes place in the chamber with magnesium powder.
1mark
c) Name one gas which escapes from the chamber containing magnesium powder.
Give a reason for your answer 2marks
11. Name the following substances.
a) CH2 CH CH2 CH3 1mark
b) CH3 CH CH CH2 CH3 1mark
12. The diagram below shows the acidic and basic oxides fit into the general family of
oxides.
Acidic Basic
Oxide Oxide
a) State the name given to the type of oxide that would be placed in the shaded area.
1mark
b) Give the name of any oxide that would be placed in the shaded area. 1mark
13. Study the information in the table below and answer the questions that follow. The
letters do not represent the actual symbols of the elements.
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Substance Solubility in water Electrical conductivity
Solid Molten
A Insoluble Good Good
B Soluble Poor Good
C Insoluble Poor Poor
(i) Which of the substances is highly likely to be sodium chloride? Explain 2marks
(ii) What type of bond exists in substance A? 1mark
(iii)State a possible structure in substance C? 1mark
14. Laboratory results showed the composition of a compound to be 58.81% barium,
13.72%, sulphur and 27.47% Oxygen. Calculate the empirical formula of the
compound. Ba=137, S = 32, O = 16. 2marks
15. The diagram below shows a wooden splint that was placed horizontally across the
middle part of a non-luminous flame.
Unburnt part
Charred black
a) Explain the observation made 2marks
b) Explain why non-luminous flame is preferred for heating than the luminous flame.
2marks
16. 200cm3 of oxygen gas took 60 seconds to diffuse through a porous plug. Determine
the time taken by 300cm3 of sulphur (IV) oxide to diffuse through the same plug under
the same conditions.
(O=16, S = 32) 3marks
17. Explain why?
(i) Both methane and diamond are covalently bonded. Methane is a gas but diamond
is a solid with very high melting point. 2marks
(ii) Ammonia is dissolved in water using an inverted funnel. 1mark
18. Explain giving reasons why?
a) Sulphuric acid is not used with marble in the preparation of carbon (IV) oxide
2marks
FOR MARKING SCHEMES AND OTHER SUBJECTS PREDICTIONS INBOX MR CHEPKWONY ON 0724351706
KCSE CHEMISTRY 2020 PREDICTION PAPERS
Kenya Certificate of Secondary Education (K.C.S.E.)
Chemistry Paper 1,2, &3
PREDICTION 1
PAPER 1
1. An element K has atomic number 20 while element M has atomic number 8.
a) Write the electronic configuration for K and M 2marks
b) Write the symbol of the most stable ion of K and M 2mks
2. Molten Lead (II) bromide is electrolyzed using carbon electrodes. Write the half
equations of the reactions that occur at the anode and the cathode.
a) Anode 1mark
b) Cathode 1mark
3. Explain why the conductivity of metals decreases with increase in temperature.2mks
4. Three metal oxides XO, YO, and ZO are heated with powdered metal Y. Hot
powdered Y will remove oxygen from XO but not from ZO. Arrange the metals in
order of reactivity, starting with the most reactive.
1mark
5. Some sodium chloride was found to be contaminated with copper (II) oxide. Describe
how a sample of sodium chloride can be separated from the mixture. 2marks
6. Hot platinum wire was lowered into a flask containing concentrated ammonia solution
as shown below.
Glass rod
Hot platinum wire
Concentrated Ammonia Solution
State and explain the observations made. 3marks
7. The set up below represents the apparatus that may be used to separate a mixture of
two miscible liquids C and D whose boiling points are 800C and 1100C.
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a) Name B 1mark
b) What is the purpose of the thermometer 1mark
c) Which liquid was collected in the test tube? 1mark
8. Draw a dot (.) and cross (x) diagram to show bonding in carbon (II) oxide.
2marks
9. Ammonium nitrate was gently heated and the products collected as shown in the
diagram.
a) Identify:
i. Colourless liquid H 1mark
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ii. Gas G 1mark
b) Describe one physical and one chemical test that can be used to identify gas G.
2marks
10. Air was passed through several reagents as shown in the flow chart below.
Escaping gases
Concentrated Excess heated Excess heated
Air KOH solution copper turnings magnesium
powder
a) What is the purpose of concentrated potassium hydroxide solution? 1mark
b) Write an equation for the reaction which takes place in the chamber with magnesium powder.
1mark
c) Name one gas which escapes from the chamber containing magnesium powder.
Give a reason for your answer 2marks
11. Name the following substances.
a) CH2 CH CH2 CH3 1mark
b) CH3 CH CH CH2 CH3 1mark
12. The diagram below shows the acidic and basic oxides fit into the general family of
oxides.
Acidic Basic
Oxide Oxide
a) State the name given to the type of oxide that would be placed in the shaded area.
1mark
b) Give the name of any oxide that would be placed in the shaded area. 1mark
13. Study the information in the table below and answer the questions that follow. The
letters do not represent the actual symbols of the elements.
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Substance Solubility in water Electrical conductivity
Solid Molten
A Insoluble Good Good
B Soluble Poor Good
C Insoluble Poor Poor
(i) Which of the substances is highly likely to be sodium chloride? Explain 2marks
(ii) What type of bond exists in substance A? 1mark
(iii)State a possible structure in substance C? 1mark
14. Laboratory results showed the composition of a compound to be 58.81% barium,
13.72%, sulphur and 27.47% Oxygen. Calculate the empirical formula of the
compound. Ba=137, S = 32, O = 16. 2marks
15. The diagram below shows a wooden splint that was placed horizontally across the
middle part of a non-luminous flame.
Unburnt part
Charred black
a) Explain the observation made 2marks
b) Explain why non-luminous flame is preferred for heating than the luminous flame.
2marks
16. 200cm3 of oxygen gas took 60 seconds to diffuse through a porous plug. Determine
the time taken by 300cm3 of sulphur (IV) oxide to diffuse through the same plug under
the same conditions.
(O=16, S = 32) 3marks
17. Explain why?
(i) Both methane and diamond are covalently bonded. Methane is a gas but diamond
is a solid with very high melting point. 2marks
(ii) Ammonia is dissolved in water using an inverted funnel. 1mark
18. Explain giving reasons why?
a) Sulphuric acid is not used with marble in the preparation of carbon (IV) oxide
2marks
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