CHEMISTRY TOPICAL QUESTIONS AND ANSWERS - ATIKA SCHOOL

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.

Chemistry Topics

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A

KCSE Chemistry Topical Questions and Answers Dashboard since 1995

C

E

F

G

Gas Laws

I

Introduction To Chemistry

K

M

Metals

N

Nitrogen And Its Compounds

O

P

R

S

T

The Mole

W

Water And Hydrogen

State three differences between chemical and nuclear reactions.

11/10/2021

a) State three differences between chemical and nuclear reactions. (3mks)

Chemical reaction	Nuclear reaction
It takes place on the outer	Take place within the nucleus
Heat energy released is less	Heat energy released is large
Involves electrons	Involves neutrons and electrons
Affected by environmental factors	No affected by the environmental factors
such as temperature and pressure

(any three 3mks)

b) Study the figure below and answer the questions that follow

Study the figure below and answer the questions that follow

Identify the radiations A, B and C (3mks)

A-Gamma rays
B-Beta rays
C-Alpha rays

K.C.S.E Chemistry Q & A-MODEL 2018.PP1.Q N.19

25/11/2020

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

(a) Give the symbols of the o charged particles emitted by a radioactive isotope.

mass number
atomic number:

ANSWERS

K.C.S.E Chemistry Q & A-MODEL 2017.PP2.Q N.7

23/11/2020

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

The decay rates of a sample of a radioisotope of bismuth at different time intervals is indicated in the following table.

(a)(i) Draw a graph of disintegration rate against time.
(ii) Determine the half-life of bismuth.
(iii) What would be the effect on the curve if half the amount of sample of bismuth were used.
(b) Radioactivity has several applications. State one application of radioactivity in:
(i) Medicine
(ii) Agriculture
(iii) Tracers
(iv) Nuclear power station
(c) State two dangers associated with radioactivity.

ANSWERS

(ii) It would have no effect on the curve as the quantity of bismuth does not affect half-life.
(b)(i)Applications in medicine
Sterilizing surgical instruments.
Destroying cancerous tissues during radiotherapy.
Provide power to the heart pace setters.
(ii) Applications in agriculture
Monitor photosynthesis and other related processes.
Preservation of foodstuffs, by exposing
Micro-organisms to gamma rays.
Rate of absorption of a fertilizer by the plant.
(iii)Applications in Tracers
Detecting leakages in underground water or oil pipes.
(iv)Applications in Nuclear power stations.
To generate electricity.
(d) Dangers of radioactivity
Long term exposure causes genetic mutation;
Radioisotopes can be used as weapon of mass
Destruction;
Causes skin cancer;
When tested causes environmental pollution.

K.C.S.E Chemistry Q & A - MODEL 2017.PP1.QN.2

22/11/2020

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

Calculate the values of X and Y in the following nuclear equation.

ANSWERS

X=231
Y= 90

K.C.S.E Chemistry Q & A - MODEL 2016.PP1.QN.11

19/11/2020

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

a)Complete the nuclear equation below:

(c)Give one harmful effect of radioisotopes.

ANSWERS

Instant / cause death
Cause cancer
Cause gene mutation

KCSE Chemistry Q & A - MODEL 2019.PP1.QN.22

19/11/2020

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

The diagram in Figure 6 Shows radiations emitted by a radioactive sample.

(a) Identify radiations:
- (i) M …………….(1 mark)
- (ii) N ……………...(1 mark)
(b) Explain what would happen when a sheet of paper is placed in the path of the two radiations. (1 mark)

Expected Response

K.C.S.E Chemistry Q & A - MODEL 2015.PP1.QN.19

17/11/2020

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

A radioactive substance weighing M kg took 1900 years for the original mass to reduce to 15 kg. Given that the half life of the radioactive substance is 380 years;
(a) Determine the original mass of the radioactive substance.
(b) State two uses of radioactivity in medicine. .

ANSWERS

K.C.S.E Chemistry Q & A - MODEL 2014.PP1.QN.8

15/11/2020

KCSE Chemistry 2014 Topical Questions and Answers

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

ANSWERS

(b) (i) Cobalt 60 is used to detect the activity of the thyroid gland.
(ii) To sterise equipment/treatment of cancer/radio active Na for disorders in blood circulation/Barium meal for ulcers/detect fractures in bones.

K.C.S.E Chemistry Q & A - MODEL 2013.PP2.QN.6

13/11/2020

KCSE Chemistry 2013 Topical Questions and Answers

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

(a) distinguish between a neutron and proton
(b) What is meant by a radioactive substance?
(c) State two dangers associated with radioactive substance in the environment

(i) What is the atomic
a. Mass of Y
b. Number of Y
(ii) What name is given to the type of reaction undergone by the isotopes of hydrogen?
(e)(i) What is meant by half-life of a radioactive substance
(ii) 288 g of a radioactive substance decayed to 9 g in 40 days. Determine the half-life of the radioactive substance

ANSWERS

(a)A proton has a +ve charge while a neutron has no charge
(b)Substances undergo radioactive decay or disintergration.
(c)- causes genetic mutation
- can cause death
- prone to cancer
(d)(i)I Atomic mass of a = 4
IIAtomic number of b = 2
(ii)Fusion

K.C.S.E Chemistry Q & A - MODEL 2013.PP1.QN.8

11/11/2020

KCSE Chemistry 2013 Topical Questions and Answers

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

Draw a labeled diagram to illustrate how alpha, beta and gamma radiations can be distinguished from each other.

ANSWERS

KCSE Chemistry Q & A - MODEL 2001.PP1.QN.1

9/11/2020

KCSE Chemistry 2001 Topical Questions and Answers

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

Study the nuclear reaction given below and answer the questions that follow

Expected Response

KCSE Chemistry Q & A - MODEL 2000.PP1.QN.13

4/11/2020

KCSE Chemistry 2000 Topical Questions and Answers

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

A radioactive isotope X₂ decays by emitting two alpha (a) particles and one beta (β) to from

214 Bi

83

(a) What is the atomic number of X₂?

(b) After 112 days, 1/16 of the mass of X₂ remained. Determine the half life of X₂

Expected Response

K.C.S.E Chemistry Q & A - MODEL 2012.PP1.QN.9

1/11/2020

KCSE Chemistry 2012 Topical Questions and Answers

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

120g of iodine - 131 has a half life of 8 days and decays for 32 days. On the grid provided, plot a graph of the mass of iodine - 131 against time.

ANSWERS

KCSE Chemistry Q & A - MODEL 1999.PP1.QN.26

30/10/2020

KCSE Chemistry 1999 Topical Questions and Answers

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

The graph below shows the mass of a radioactive isotope plotted against time

(a) Using the graph, determine the half – life of the isotope
(b) Calculate the mass of the isotope present after 32 days

Expected Response

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