CHEMISTRY TOPICAL QUESTIONS AND ANSWERS

KCSE Chemistry Topical Questions and Answers Dashboard since 1995

1/1/2025

These are chemistry questions and answers categorized according to topics, papers i.e. Paper 1 and 2, Levels i.e. form 1 to form 4, kcse year the examination was done and section A or B
Select topic/category to open topical questions from that particular option provided.

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KCSE Chemistry Topical Questions and Answers Dashboard since 1995

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a) On the grid provided, plot on the same axis, the graph of volume of gas produced against time (4mks)

​b) From the graph, determine the rate of reaction of both acids at 55 seconds

​i) 1M sulphuric (VI) acid (1mk)

​ii) 1M ethanoic acid (1mk)

c) The rate of reaction of H2SO4 is twice that of ethanoic acids. This is because H2SO4 is stronger while ethanoic acid is a weak acid.

​c) Explain the difference in the rate of evolution of the gas as determined in (b) above (2mks)

d) Calculate the number of moles of hydrogen gas produced when 10cm magnesium ribbon is completely reacted with 1M sulphuric (VI) acid. (Molar gas volume = 24dm3 at r.t.p) (2mks)

​e) What mass of magnesium had therefore reacted? (Mg = 24) (2mks)

​​a) Name the following;

​i) Gas L (1mk)

​ii) Gas H (1mk)

​iii) K (1mk)

​​b) Name the processes involved in the following steps

​i) Step I (1mk)

​ii) Step II (1mk)

​​iii) Step III (1mk)

​c) Draw the structure of compound E (1mk)

​d) Write a chemical equation for the complete combustion of substance F (1mk)

​e) Name the condition and reagents in step III

​i) Condition (1mk)

​ii) Reagent (1mk)

​f) Calculate the mass of salt Q that would be formed by using 21.9kg of G when it reacts with excess sodium hydroxide (2mks) (C = 120, H = 1.0, Na = 23.0, O = 16.0)

​g) i) Draw the structure of polymer D (1mk)

​ii) State one use of the above polymer (1mk)

i) Which metal is used above (1mk)

ii) Which gas was produced (1mk)

​iii) What will be the colour of phenolphthalein indicator in the resulting solution? (1mk)

​Name one gas used together with oxygen in welding other than acetylene gas (1mk)

State two other uses of the gas named above (2mks)

​Explain why potassium is kept under paraffin while phosphorous is kept under water

KCSE Chemistry 2018 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

KCSE Chemistry 2018 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

KCSE Chemistry 2017 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

KCSE Chemistry 2017 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

KCSE Chemistry 2016 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

KCSE Chemistry 2015 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

KCSE Chemistry 2019 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

KCSE Chemistry 2019 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

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b) From the graph, determine the rate of reaction of both acids at 55 seconds

i) 1M sulphuric (VI) acid (1mk)

ii) 1M ethanoic acid (1mk)

c) The rate of reaction of H₂SO₄ is twice that of ethanoic acids. This is because H₂SO₄ is stronger while ethanoic acid is a weak acid.

c) Explain the difference in the rate of evolution of the gas as determined in (b) above (2mks)

d) Calculate the number of moles of hydrogen gas produced when 10cm magnesium ribbon is completely reacted with 1M sulphuric (VI) acid. (Molar gas volume = 24dm³ at r.t.p) (2mks)

e) What mass of magnesium had therefore reacted? (Mg = 24) (2mks)

a) Name the following;

i) Gas L (1mk)

ii) Gas H (1mk)

iii) K (1mk)

b) Name the processes involved in the following steps

i) Step I (1mk)

ii) Step II (1mk)

iii) Step III (1mk)

c) Draw the structure of compound E (1mk)

d) Write a chemical equation for the complete combustion of substance F (1mk)

e) Name the condition and reagents in step III

i) Condition (1mk)

ii) Reagent (1mk)

f) Calculate the mass of salt Q that would be formed by using 21.9kg of G when it reacts with excess sodium hydroxide (2mks)
(C = 120, H = 1.0, Na = 23.0, O = 16.0)

g) i) Draw the structure of polymer D (1mk)

ii) State one use of the above polymer (1mk)

iii) What will be the colour of phenolphthalein indicator in the resulting solution? (1mk)

Name one gas used together with oxygen in welding other than acetylene gas (1mk)

Explain why potassium is kept under paraffin while phosphorous is kept under water