CHEMISTRY REVISION QUESTIONS FORM 1 - 4
1. Identify ten substances made by application of chemistry.
2. How chemistry is applied in your community?
3.
Chemistry is an important
subject due to its wide applications in life. The knowledge and skills of chemistry are also very important in our daily lives as they are widely applied in different
areas. Explain the fact of the statement
using six (6) points.
4.
With examples of chemical
substances, explain how chemistry is commonly applied
at you home.
5. How would life
be if there was no chemistry
at all?
6. Why is it important to study chemistry? Explain with six (6) points
7.
Mpundukwa believe that chemistry is
not important subject, thus he always not like to enter the chemistry session at his school. How can you advise Mpundukwa
to attend the chemistry session by using six (6) points?
8.
Explain seven areas where chemistry is applied
9.
Fill in the following
table by giving
three (3) products
that are made by the applications of chemistry
in each at the following fields
|
FIELDS/AREAS |
PRODUCTS |
|
Agriculture |
|
|
Medicine and pharmacy |
|
|
Home care
products and cosmetics industries |
|
|
Food and beverage industries |
|
|
Construction materials |
|
|
Textile industries |
|
|
Transport |
|
|
Chemical industries |
|
10. Which chemical
substances are used at your home?
11. Why laboratory rules should be obeyed by everyone? Use three (3) points
12. Why should
chemicals in the laboratory be labeled and well closed after use?
13. Give reasons
to support each of the following statements
i.
A laboratory should
be equipped with fire extinguisher
ii.
Dangerous experiments must be demonstrated by the teacher
only. They shoud be done outside in the open space or in the
fume chamber
iii.
A laboratory should have large windows
iv.
Chemicals that are not labeled
should not be used in the laboratory
v.
Why should chemicals in the laboratory be labeled and well closed after use
vi.
Laboratory should have large space
vii.
Fume chamber
is of great important in the laboratory
viii.
Laboratory should have rough surface
ix.
Most of laboratory apparatus are made by glass.
Give four (4) reasons
x.
Never enter in the laboratory without permission
xi.
Safety signs/symbols are of great importance in the laboratory
xii.
A chemistry laboratory must have safety
measures
xiii.
Chemistry laboratory exits
like doors open outwards
xiv.
It’s important to familiarize with the laboratory apparatus
xv.
Luminous flame produce
soot
xvi.
Non luminous flame do not produce soot
xvii.
Luminous flame is used for lighting than non-luminous flame. Give two reasons
xviii.
Non luminous flame
is used in welding
or during heating
xix.
Materials should never be
thrown or put in water
sink
xx.
Fume chamber should
be built in the laboratory
xxi.
In a storey
building, the chemistry
laboratory should be on the lowest floor
xxii.
Laboratory floor should
never be polished
14. How can you help a fellow
student who has been
burnt with chemicals
in the laboratory?
15. State three advantages of having laboratory rules
16.
The following are possible
causes of accidents that occur in chemistry laboratory. State how can you avoid
them
a) Poisonous chemicals left in an unlocked cupboard
b)
A students picking up a bottle with concentrated sulphuric acid by the neck
c)
Concentrated acids are stored in the upper most shelf
of cupboard
17.
Some beakers, syringes, measuring
cylinders and troughs
are made of plastic. What are the advantages of plastic containers?
18. Most of laboratory apparatus are made up by glass.
Give five (5) points
19. Give reasons
for the following
i.
A candle may be used where the experiment does not
need heating to a high
temperature yet it’s disadvantageous.
ii.
The spirit burner flame may be soot
free but the flame is not used in many experiments.
20.
(a) Draw the warning symbol you would
expect to see on
i.
A can of petrol
ii.
A bottle of caustic soda
(b) Why are hazard signs
better than words?
21.
Your teacher may advice you on things
you should never do
in the laboratory. For each of the rules
below, write what might happen
if you never followed instructions
a) Never enter the laboratory in the absence of teacher
b) Never run around
in the laboratory
c) Never use broken apparatus
d)
Never eat or drink in
the laboratory
e) Never quarrel or fight in the laboratory
f) Never use laboratory apparatus
for drinking or storing food
g) Never throw any
solid into the sink or
waterways
h)
Wash your hands with soap before you leave a laboratory
i)
Replace the cover (stopper) after using a chemical.
22.
It is a good practice to keep a
list of laboratory rules on the wall of a chemistry laboratory. You are required
to compile a list of ten such rules. The rules should
warn students or guide them on how to
a) Take chemicals
safely from containers.
b) Avoid mixing
up of chemicals unnecessarily.
c)
Prevent blocking of the sink and waterways.
d) Discourage doing unauthorized experiments.
e) Avoid exposure to dangerous gases
f) Control the movements of people in the laboratory
g) Handle hot objects over flame
h) Keep the floor and bench top clean, dry and tidy
i)
Stop any attempt
to eat, drink or
keep any food in the laboratory
j)
Boil liquids safely
23.
(a) How would you treat
i.
A minor cut
ii.
A minor burn
(b) What would you do in case of a more serious
injury?
24.
How can you handle or take precautions/safety measures
when using the chemicals with the following chemical symbol or name
a) Flammable
b) Corrosive
c)
Irritant
d)
Oxidant
e)
Toxic
f) Harmful
g)
Explosive
25. Differentiate the flame produced
by candle and that of spirit burner
26.
A
Bunsen burner is the most commonly used source of heat in the laboratory than any other
sources of heat. Explain with five (5) reasons
27.
Why non-luminous flame is preferred most to be used as the source of heat than luminous
flame
28. Why the following
type of flame are given that name
a) Luminous flame
b)
Non luminous flame
29. What will you do if
you come into contact with the following situations in the laboratory
i.
Some chemicals come into
contact with your eyes
ii.
Corrosive chemicals like concentrated acids come into contact with your skin
iii.
Some chemicals enters into your mouth
iv.
Your hands are wet and you want to put off the electricity since you have finished the task
v.
Your friend’s clothes catch fire
vi.
Unlabeled chemicals on benches
vii.
Glass apparatus cut your skin
viii.
Your friend is on electrical shock
ix.
You want to perform experiment that
involves harmful/poisonous gases but there is
no fume chamber in your laboratory
x.
A fire starts
in your laboratory.
30. Explain the importance of giving
First Aid to victims of accidents.
31. If your family member has a burn, how can you help him/her?
32.
Explain how can you administer first aid to your classmate who has just had concentrated sulphuric acid spilled
on his/her skin.
33.
Why is important for one
to know and observe safety rules in the laboratory. Give three (3) importance
34. What are advantages
of Bunsen burner over other sources of heat?
Give five (5) reasons
35. Explain the importance of handling safely
the laboratory apparatus.
36. How will you light
a Bunsen burner?
37. What happen when a piece of white paper is
placed into a non-luminous flame?
38. How would you use a Bunsen
burner to produce different types of flame?
39. How can you adjust
or use Bunsen burner to get the following types of flame
a)
Luminous flame
b) Non-luminous flame
40. Which sources of heat are commonly
used in the laboratory?
41.
How can you differentiate a flame formed
by closing air holes
and one formed by opening the air holes of the Bunsen burner? Use seven (7) points
42.
What is burning back or sticking
back? How is it caused? What dangerous effect may occur? How to correct it?
43. Why chemistry
laboratories are not built on top or upstairs or over other laboratories
44.
Why a laboratory user should wear laboratory protective gears like goggles,
face mask and laboratory
coat
45. Why open shoes are not allowed
in the laboratory
46. Long hairs,
loose or floppy clothing are not allowed
in the laboratory. Explain
47. Explain the different causes of accident
in the laboratory. Use six (6) points
48.
Explain the preventive measures for common accident that are likely
to occur in the laboratory. Use six (6) points
49.
Chemistry laboratory apparatus are
special tools and equipment that are used in the laboratory. They are used for various purposes.
By giving example
explain the function
of different apparatus
depending on the following categories
a) Apparatus for measuring
b)
Apparatus for testing
c) Apparatus for heating
d)
Apparatus for filtering
e) Apparatus for grinding
f) Apparatus for holding
g) Apparatus for storage
h) Apparatus for scooping i) Apparatus for safety
50. Study the given Bunsen
burner flame and answer the following questions
a) Is the flame luminous
or non-luminous explain?
b)
How can you adjust
the Bunsen burner to
get this flame.
c) Which letter in the flame represents the
i.
Region of unburnt
gas?
ii.
Hottest part of the flame
iii.
Region where
all gas is burnt
with air mainly
supplied from outside
the chimney
51.
The following are the steps to
follow in lighting of the Bunsen burner. However the steps are not in correct order. Re write them in correct
sequence
i.
To extinguish the flame turn off the gas
tap to stop the gas flow
ii.
Light the gas at
the top of the barrel
with a lighted match stick.
iii.
Turn the color to
close the air hole completely
iv.
Keep your
face away from the top of the
barrel
v.
Adjust the gas tap until
the supply of gas is enough for a flame.
vi.
Turn on the gas
fully to ensure that plenty
of the gas enters the burner
52. Which part of a flame
has a lowest temperature?
53. How to light a Bunsen burner?
Give six (6) procedures
54. In what ways is a luminous
flame important?
55.
Assume that you are doing an
experimentin the laboratory at 07:30pm and suddenly the lights went off. Give two reasons to justify the fact that you would consider
luminous flame rather than non luminous
flame as an alternative source for lighting?
56. Why petrol
and diesel not recommended to be
used as fuels in the laboratory?
57. Why it is necessary to use wire gauze when boiling
liquid in a beaker? Give three(3)
points
58.
The non-luminous flame is used in different areas.
Give three (3) such areas and explain why the flame is preferred by the users in those areas.
59. (a). How is the scientific method applied in treatment of sick persons?
(b).
Explain any three problems
or facts at home or at school whose answers can be found using scientific method.
(c). Assume most students in your class fail to perform
a certain chemistry
experiment assigned by the teacher.
i.
Identify
a problem that you can investigate.
ii.
Formulate the hypothesis
iii.
List down a dependent
variable, an independent variable and a control variable in your investigation.
iv.
Design
an experiment to test your variable
60. What are the advantages of using the scientific method in doing science experiments?
61. What are the application of scientific procedures/methods in daily life
62. Explain three
factors that affect
the problem being investigated
63.
To design a suitable experiment,
you must find out the factors that affect the problem you want
to investigate.
i.
Name the
factors that affect the problem
to be investigated
ii.
Explain the three
types of factors named in (i)
above
64.
What would you do if the results
obtained do not support the hypothesis? Give three (3) points.
65. Describe the six
(6) main steps of scientific methods with vivid examples.
66. What would
happen if there were no
experiments?
67. Explain the purpose of each step in the scientific procedure
or method.
68.
Effective use of four senses of
observation is important before a chemist can make conclusion. With four points, show how the senses are used as tools of observation during
experimentation by giving one example
for each.
69.
Why stone
is said to be an example of matter?
70. State two (2) characteristics of matter.
71. Explain the differences between
evaporation and boiling.
Use five (5) points
72. Give reasons
for the following
statement
i.
Why do cold foods not smell from a distance
ii.
Smell of perfume
can be felt at any corner
of the classroom
iii.
Smell of
ether (chemical) can be detected
at different points
in the laboratory?
iv.
Why do gases expand more than solids
for the same increase in temperature?
v.
Gases expand more than solids
for the same increase in temperature
vi.
When metal such as copper is
heated, it expands. Explain what happens to the metal particles during expansion.
vii.
When a container of coffee is
opened in as room, people in different parts of the room may notice its smell.
Use the kinetic theory of matter to explain
how this happen.
viii.
Once you open a freezer,
you may find an ice on its walls. How does the ice form?
ix.
It is
easy to pour liquid
x.
A gas will completely fill any container
xi.
A solid expands
when heated.
xii.
Cooking pots, pans,
and utensils made by metals?
xiii.
Iron materials make sound when they
are hit. Explain
xiv.
When you touch a metal during cold weather you feel that it is cold, but when you touch a metal
during hot weather you feel it
is hot. Explain
xv.
Saturated solutions dissolve
more solutes when heated.
xvi.
Air pressurized water fire extinguisher (APW) not suitable for fire
classes B, C and D.
xvii.
Carbon dioxide fire extinguisher not suitable for class A fire.
xviii.
Water is not used to put off fire caused
by flammable liquids
like petrol and diesel
xix.
Is not allowed
to open the bottle with petrol or diesel for period of time
xx.
Is advised to close all flammable liquids
soon after use
xxi.
Not allowed to put flammable
liquids near the open flame
xxii.
Fires that involves
flammable liquids should be put off/out using sand or fire blanket
xxiii.
Iron sheets turn brown when exposed to wet air for a long time
xxiv.
Commodities like hand bags and camera bags for sale are packed
with silica gel
xxv.
Water is
not advised to extinguish fire classes A and B
73.
Hurricane and tin lamps are not
advised to be used
in the laboratory. Use two (2) points
74.
Why may a flame produced by a
spirit lamp not be good for heating in the laboratory? give two reasons. Name the
type of flame produced by a
spirit lamp.
75.
What are the conditions for substances to be called matter?
76. Why liquids and gases are categorized as fluids?
77. Describe gases,
liquids, and solids in terms of the following
a)
Shape
b) Volume
c)
How they
flow
d)
Density
e)
Compressibility
f) Space between
particles
g)
Movement of particles
78. What are differences between
physical change and chemical change?
Use six (6) points
79. Categorize the following as either chemical
or physical changes
i.
Ammonium carbonate is dissolved in water gradually
with stirring. The solution becomes
very cold.
ii.
Exactly 5g of copper
filings are heated
strongly in air. At the end of the reaction,
the mass is found to be 5.15g
iii.
A
small piece of sodium was dropped into water. It darted about on the water surface
and finally it burst into flames.
iv.
Copper (II) sulphate is heated strongly;
it changes from blue to white. On addition of water
to white substance, it changes back to blue
v.
When ethanol is mixed with water, a homogeneous solution is formed.
When the solution
is distilled, the two liquids
are obtained.
vi.
If
water is kept in a deep freezer,
it solidifies to ice. If the ice is kept in the sun, it liquefies
to water.
vii.
Water is added drop wise to dry
calcium oxide on a watch glass. Heat is developed, steam is formed,
the oxide cracks
and puffs up and finally
crumbles to a powder about three
times as bulky.
viii.
Burning of a candle
ix.
Decaying of meet
and teeth
x.
Freezing of juice
in a bottle
xi.
Rusting of iron
xii.
Burning of wood
xiii.
Drying of wet clothes
xiv.
Cooking food
xv.
Burning charcoal
xvi.
Rusting of iron sheets
xvii.
Souring of milk
xviii.
Dissolution of common sal in water
xix.
Sublimation of iodine from the mixture
of iodine and sand
80.
What are the importances’s of
changing from one state of matter to another? Give six (6) reasons
81.
Name the changes
of matter from one state to another
depending on the following
i.
Ice to water
ii.
Water to ice
iii.
Ice to water vapour
iv.
Water vapour to ice
v.
Water to water vapour
vi.
Water vapour
to water
82.
How can you differentiate the changes that occur when the juice
in a bottle freezes and that if wood is burnt
83. Why some elements are assigned with one letter
and other with two letters?
84.
What is the importance of having
the rules for assigning the chemical symbols? Use five (5) points
85. What are the uses of
chemical symbols? Explain with five (5) points
86.
Why some of the elements are assigned symbol
with only one letter while other bears
two letters?
87. What is significance of using chemical
symbols? Explain with five (5) points
88.
The use of chemical
symbols has made it easier
for chemists and other people.
Explain with five (5) points
89.
The following are substances that
are made up of one, two or more components: common salt,mud, juices,
milk,water, sulphur, chlorine,
iron, zinc and soft drinks.
i.
Classify the above
listed items as either compound, mixtures, metals and non-metals
ii.
Discuss each item and give reasons for classifying
it as a compound or a mixture.
90. What is the difference between metals and non-metals? Use six
(6) points
91. Why metals
can be made into wires and iron sheets but not non-metals. Explain
92. Differentiate between
compounds and elements.
93. Table salt is a mixture. Explain
with five (5) points
94. Muddy water
is a mixture. Explain with five
(5) points
95. Air is the mixture.
Explain with five points
96.
Identify various solutions available
at your home and school
and classify them into solid,
liquid and gaseous
solutions.
97.
Briefly how can you distinguish
homogeneous mixture and heterogeneous mixture just by their appearance? Use three (3) points
98. Why only fractional distillation is used to separate ethanol
from water?
99. Suggest one method for separation of each of the following
mixtures
i.
Iodine and sand
ii.
Green solution from leaves
iii.
Alcohol and water
iv.
Iron pieces
from sand
v.
Iron fillings and powdered
calcium carbonate
vi.
Sand and water
vii.
Chalk and water
viii.
Water from copper
(II) sulphate
ix.
Serum from a blood sample
x.
Water and ethanol
xi.
Sodium chloride and ammonium
chloride
xii.
Kerosene (oils) and water
xiii.
Muddy water
xiv.
Dust and salt
xv.
Ink colours
xvi.
Iodine and sand
xvii.
Crude oil
xviii.
Sand and rice
xix.
Iron fillings
and table salt
xx.
Sodium chloride and water
xxi.
Pieces of iron and copper
xxii.
Sand and salt
xxiii.
Chlorophyll from leaves
xxiv.
Iron fillings and sulphur
xxv.
Common salt and water
xxvi.
Kerosene, cooking
oil and water
xxvii.
Oil from plant
seeds
100.
Why mixtures of the same boiling points
cannot be separated
by fractional distillation?
101.
Briefly how can you distinguish
solution and suspension just by their appearance? Use three (3) points
102.
How can you differentiate the mixture of chalk with water and that of common salt with water?
Use four points
103.
How is evaporation applied at home?
104.
In which areas
can you apply the knowledge
of chromatography?
105.
Describe two examples
where simple distillation is used in daily life.
106.
How are solutions, suspensions and emulsions
used in daily life?
107.
Are the formations of homogeneous colourless solutions always physical
changes? Explain
108.
What changes do we encounter in our daily lives
that are good examples of physical changes
and chemical changes?
109.
Why can saturated sugar solution dissolve
more sugar after being heated?
110.
Air is the mixture and not compound.
Explain
111.
List any five noble gases
112.
Give an example
for the following
types of solution states:
a) Liquid
b)
Solid
c) Gas
113.
Explain how combustion can be applied
in the following areas
a) Laboratories
b)
Homes
c) Industries
d)
Transport
114.
According to the laboratory rules, what should you do in the following situations?
a)
While boiling water,
you realize that you need to get a book from the classroom.
b)
There is
unused acid left in the test tube after you finish your experiment
c)
You need to use water and there is a bottle
containing a clear liquid on the bench
but you are not sure of its content
d)
Your friend suggests that you carry apparatus out of the laboratory
e)
You need to switch off electricity
f)
You have finished
biology experiments for the day
115.
Explain effects of rusting in your community
116.
What are the four main components of air?
117.
What are differences between combustion and heating
118.
What are similarities between combustion and rusting?
119.
What are similarities between burning and rusting
120.
What are differences between burning and rusting
121.
What are differences between combustion and rusting?
122.
State the chemical composition of the extinguishing agents of each of the following portable fire extinguishers: carbon dioxide extinguisher,dry chemical
extinguisher,wet chemicalextinguisher, ABC extinguisher
and foam extinguisher.
123.
Mpundukwa is the student
at KAMBARE SECONDARY SCHOOL he performed
an experiment basing on the following procedures.
a. He measured
about 100cm3 of water and pours it in a beaker.
b. He added a spatulaful of the common salt in the beaker and stir.
c.
He
continued adding more salt to the solution
and stirring until
no more salt can dissolve
d.
He
placed the solution
on the tripod stand and heat gently with constant
stirring while heating
e. He stopped
stirring when the salt dissolves
f.
He placed the beaker with the
solution that is half-filled with cold water and allows cooling for 5 minutes. He recorded an observation
i.
What was the aim
of the experiment?
iii.
What type of solution
is obtained ate room temperature when no more salt
can dissolve? Explain with reason
124.
Why when solids are dipped into beaker with water
displaces some water?
Give two reasons
125.
Three substances A, B and C
are mixed together. Some of their properties are summarized in the table below
|
Substance |
Soluble in water |
Soluble in kerosene |
|
A |
No |
Yes |
|
B |
No |
No |
|
C |
Yes |
No |
i.
Which substance could be salt? Explain your choice
ii.
Describe how pure samples of A, B and C could
be obtained from this mixture.
126.
During the separation of ethanol and water Liebig condenser is used.
a)
What role does the
Liebig condenser play?
b)
If
you do not have a Liebig
condenser, what will you use to carry
out this simple
distillation?
127.
Fractional distillation separates the miscible liquids
with different boiling
points. Assume you are in the laboratory and you want
to separate water and ethanol which have boiling points of 100 and 72 degree of centigrade respective.
a) Which liquid
distills first and why?
b) What role does fractionating column play?
128.
Juma went to the laboratory; he accidentally mixed spirit with water. With the aid of diagram
explain how you would help Juma to separate
the mixture.
129.
Yunice was provided with the
following reagent sand, salt, distilled water and kerosene. She was asked to prepare
the mixture A, B and C from the given reagent,
substance A contain
the mixture of sand and distilled water, substance B contain the mixture
of salt and distilled water and substance C contain mixture
of kerosene and water.
a) Name the mixture found
in substance A, B and C
b) What is the suitable
method to separate
the component found
in substance A, B and
C.
c)
Contrast mixture
A and mixture
B by four points
130.
Juma went to the laboratory; he accidentally mixed cooking oil with water.
With the aid of
diagram explain how you would
help Juma to separate the mixture.
131.
Your friend dropped some salt on
the ground accidentally. The salt got mixed up with dust and sand. You are required to advise your friend on what to
do at home so as to get his salt as clean
as possible. Explain
132.
As
a chemistry taker how can you separate
the following when mixed together
with the aid of apparatus used to separate them,
cooking oil, kerosene and water with density
0.92g/dm3, 0.64 g/dm3 and 1g/dm3 respectively.
133.
Chunya village is place where most
of people complain of drinking water containing too much salt. As an expert of chemistry explain the technique with
the aid of diagram that could separate
salt from water.
134.
When water and kerosene are mixed
in the same container which one forms the upper layer of the mixture give reason?
135.
How can you separate a mixture
of salt and common salt? use flow chart to explain
136.
How can you apply the knowledge of separating
mixtures in everyday life?
137.
Answer the following questions i.Give
any four (4) causes of fire
ii. Briefly explain
any seven (7) ways
of preventing fire
iii. Give three
ways that will enable a fire to start or continue to burn and control a fire.
138.
What are conditions necessary for the following to occur
a)
Fire b) Rusting
139.
What factors accelerate to the rusting
process to occur?
Give three (3) factors
140.
Why rusting of iron is the chemical
change? Give five (5) reasons
141.
Asubuhi njema’s child was sick. When she took her to the hospital,
she was prescribed some medicine including a bottle of syrup.
The bottle was written: shake before use. What does this statement signify?
142.
A student accidentally broke a
beaker containing copper (II) sulphate crystals. He decided to separate the blue crystals from the small
pieces of glass by first dissolving the mixture and then filtering. What were his next steps?
143.
List down five elements with their corresponding chemical symbols which start with ‘C’
144. Why fire caused
by electricity is not given their own full classes of fire?
145.
Briefly explain methods
used in preventing rusting
of iron materials.
146.
Why water is not suitable
for extinguishing fires caused by flammable liquids?
147. state the burning materials in each of the following
classes of fire
a) class A
b) class B
c) class C
d) Class D
e) Class F
148.
Portable fire extinguishers should
be used in the right ways to quickly put out dangerous fire. What are main
precautions should be taken when using portable fire extinguishers.
149.
Why carbon dioxide
is used to extinguish or put off the fire?
150.
By
using locally available materials in your school, state how the fire can be extinguished in the following situations
a) Kerosene spilled
on the floor catches fire.
b) Friend’s clothes
catch fire which gets out of her control.
151.
Explain the application of
different methods/techniques used to separate mixtures in daily life.
152.
Suppose a truck carrying kerosene
gets an accident, and unfortunately fire breaks out, suggest
a) The suitable
fire extinguisher to use. Give reasons
b) The fire extinguisher not suitable for use. Give reasons
153.
(a). List down other areas where combustion is applied. (b). In each case,
mention the combustible materials.
116.
A
student was preparing
food for the family using hot oils on frying
pan. Accidentally, the pan tipped over and a huge fire spread on the kitchen floor.
a)
Which fire extinguishers would be suitable
for putting out the fire? Explain
b)
Which fire extinguishers would not be suitable for putting out fire? Explain
117. With the aid of diagram illustrate how portable fire extinguisher
should be used.
118. State what is observed
when the following simple experiments are performed
i.
Carbon dioxide gas is passed through lime water for 32 seconds
ii.
Water is added to white copper
(II) sulphate
iii.
A glowing
splint of wood is lowered
into gas jar full of carbon dioxide.
119. State the method which
will be used to protect
each of the following from rusting
a) Iron sheets
b) Bicycle
c) Metal pipes
d) Machine parts
e) fragile instruments like cameras
f) Tin cans
g) Cars
h) Taps, kettles
and car bumbers
120.
A student
wants to put out hazardous
fire whose flame
is shown in the given diagram below
i.
State which part of the flame the student should
aim to extinguish the fire. Explain
ii.
Why is it not advisable
to aim at other two positions
o0f the flame?
121. Answer the following questions
i.
Suppose your laboratory does not
have any water, mention two (2) possible dangers or accident of using it
ii.
Explain what will happen if a mixture
of sand and ammonium chloride
is heated in a flask
iii.
Explain the process that you will use to separate compound
N that boils at 343K and compound P which boils at 345K
temperatures. Which compound will be the first to be separated than the other give reason.
iv.
Why are
there laboratory rules? Give two
reasons
122. The mixture
of sand and potassium can be separated by heating. Give reason
123. Write the chemical symbols
of the following elements
a) Vanadium
b) Yttrium
c) Cobalt
d) Antimony
e) Copper
f)
gold
g) iron
h) lead
i)
Mercury
j)
Potassium
k)
Silver
l)
manganese
m)
Sodium
n)
Tin
o)
Tungsten
124. In
an experiment, two iron nails A and B were used where by 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 reasons
125.
The following are possible
causes of accidents which can occur in the chemistry
laboratory. State how can you avoid them;
a) Poisonous chemicals left in an unlocked cupboard
b) A student
picking up a bottle containing concentrated sulphuric acid by the neck
c)
Concentrated acids stored
in the upper most shelf of cupboard
126.
Why rusting occurs most in coastal
regions than in mountain regions? Give
five (5) reasons
127.
Why is not iron usually
recommended in the construction of steam pipes and boilers?
128.
Why zinc is used as a coat for
iron and not vice-versa?
129.
How does the following methods
of preventing rusting
work to prevent rust
i.
Painting
ii.
Oiling
iii.
Use of
silica gel
iv.
Tin planting
v.
Sacrificial anode
vi.
Galvanization
130.
State and give reasons whether
rust will occur
or not to each of the following
i.
Iron bar is dipped in unboiled water
ii.
Painted iron is dipped in unboiled water
iii.
Iron bar is dipped in boiling water
iv.
Oiled iron is left
outside the room over two
nights
v.
A dry iron is wrapped
with cotton wool
vi.
Silica jel is removed from camera bag
vii.
Aluminium wire is dipped in un-boiled water
viii.
Iron is put into test tube with cotton wool and anhydrous
calcium chloride
131.
There are different conditions that are necessary for rusting to take place. A form one student
at MOJA SECONDARY SCHOOL carried an experiment basing on the following set up to demonstrate the rusting of iron nails
Questions
i.
What was observed
in each test tube after three days?
ii.
Why was the water in the test
tube B boiled, and then covered with oil?
iii.
What was the function of anhydrous calcium
chloride in test tube?
iv.
From the results of the experiment, state the conditions necessary for rusting
to occur.
v.
What is the function
of the layer of oil in test tube?
132.
How can you prepare oxygen gas in the laboratory? Explain
with the aid of diagram using
two (2) ways of preparing
it.
133.
Why oxygen is collected over water? Give two (2) reasons
134.
How can you collect oxygen gas?
135.
Outline six common apparatus used
in preparation of oxygen gas using hydrogen
peroxide and potassium chlorate
136.
Name the method
or process used to collect oxygen
gas
137.
Why during preparation of gases the first few bubbles of the gas are allowed
to escape?
138.
Give reasons for the following
statement
i.
Oxygen gas is collected by downward displacement of water?
ii.
Hydrogen peroxide is preferred over
potassium chlorate in the laboratory preparation of oxygen?
iii.
Mercury oxide can be used in preparation of oxygen by heating yet it’s not
used.
iv.
Potassium permanganate can be used to prepare oxygen
gas in the laboratory however
is not commonly used.
v.
Catalyst is
used in preparation of oxygen
gas
vi.
During preparation of oxygen by decomposition potassium chlorate temperature should be regulated.
139.
Oxygen gas may be prepared in the laboratory by heating a mixture of potassium chlorate with manganese (IV) oxide. Which
of these two compounds produces the required oxygen?
Give reasons
140.
During the laboratory preparation
of oxygen, manganese (IV) oxide s used as catalyst in the decomposition reactions.
a)
What is decomposition?
b)
What is
catalyst?
c)
What is
the role of catalyst?
d)
What would happen if the
preparation of oxygen were performed
without the use catalyst?
141.
Answer the following
questions
i.
What is
the colour and smell
of oxygen gas?
ii.
What happened when the glowing splint was put in a jar of oxygen?
iii.
What do you observe when the candle
is lowered into gas jar full of oxygen gas?
iv.
What happen when the glowing splint
is put into gas jar with carbon
dioxide gas?
v.
Do oxygen burn? Give
reasons
vi.
What is the role of deflagrating spoon?
142.
How oxygen is used in the following
i.
In living things
ii.
Welding
iii.
Burning
iv.
Mining and purification of metals
v.
In rockets
vi.
Water treatment
vii.
Chemical application
143.
How can you distinguish ordinary
air from oxygen?
Give five points
144.
Most of the uses of oxygen are
related to its properties. Relate the uses of oxygen to its properties.
145.
Distinguish the meaning
of basic oxide
from acidic oxide.
146.
Oxygen is obtained
by heating a metal chlorate
in the presence of a catalyst
a)
Write the name of
metal chlorate used
b)
Write the name of product
formed other than oxygen
c)
Write the formula
and the IUPAC name of the catalyst
used
d)
Write the word equation for this reaction
e)
Draw a labelled
diagram for this laboratory preparation of oxygen.
147.
What happen when the following
occurs
a)
Metal reacts
with oxygen
b)
Non metal reacts
with oxygen
148.
How can you differentiate basic oxides and acidic
oxides using both blue and red litmus paper?
149.
Explain the industrial preparation of oxygen
gas using two methods.
150.
Draw a clearly diagram
showing the laboratory preparation of oxygen
without the application of heat?
151.
Most of oxygen
uses are dictated
by its properties. Explain
152.
A
student placed a silvery white solid on a deflagrating spoon, ignited it and then lowered
the spoon into a gas jar of oxygen. The solid burned
with a brick red flame.
a) Identify the silvery white substance
b)
Explain the nature
of the product in terms of acidic or
basic properties.
c)
Write the product
formed after burning
the silvery solid
153.
Oxygen is collected
through a downward
displacement of water
a)
Write a word equation
for the preparation of oxygen by the decomposition of hydrogen peroxide using manganese dioxide as
catalyst
b)
Is it possible
to collect pure oxygen during
its preparation? Explain
c)
Can all oxygen formed from hydrogen
peroxide be collected into gas jar? Give reasons
154.
What is
the chemical test of oxygen gas?
155.
Oxygen gas can also be prepared
by thermal decomposition of potassium chlorate
using manganese dioxide
as a catalyst.
a)
Explain the activities which will be done when preparing the gas using
this method.
b)
Draw a well labelled diagram to
show how oxygen is prepared using this method.
c) Write the word equation
for this reaction.
156.
What would you observe if;
a)
A solution of hydrogen peroxide
was added to manganese (IV) oxide?
b)
An
excess hydrogen peroxide
solution was added to a solution of potassium manganate (VII) acidified with dilute
sulfuric acid?
c) A lit candle is lowered into a gas jar containing oxygen
157.
Given a supply of hydrogen peroxide
solution, how would you use it to generate a supply
of oxygen and how would you collect the gas?
158.
What is
catalyst?
159.
How is oxygen
prepared using the following chemicals
a)
Hydrogen peroxide
b)
Potassium chlorate
160.
What would happen
if there were no oxygen in the atmosphere
161.
Hydrogen is collected
through a downward
displacement of water
a)
Write a word equation for the
preparation of hydrogen by reacting dilute acids with metals
b)
Is it possible
to collect pure oxygen during
its preparation? Explain
c)
Can all oxygen formed from hydrogen peroxide
be collected into gas jar? Give
162.
Mention four ways of preparing hydrogen in the laboratory.
163.
Give reasons for the following
a)
Hydrogen gas is collected by downward displacement of water
b)
A gas jar of hydrogen be tightly closed with a lid
c)
Hydrogen rise high in the atmosphere
164.
Hydrogen is not often found free
on its own on the earth’s surface, instead it is found
in combination with many other elements. Explain
165.
Outline six common apparatus used
in preparation of oxygen gas using hydrogen
peroxide and potassium chlorate
166.
Among the substances formed
by the combination of hydrogen
with other elements
are organic compounds. Give at
least ten examples of such
compounds.
167.
When metals and non-metals were heated in oxygen, which one burns;
a)
Vigorously? give reasons
b)
Slowly? give reasons
c)
Identify the products formed
as a result of burning the metals and non-metals in oxygen.
168.
What is observed when moist blue
and red litmus papers are placed in the test tube containing hydrogen
gas? Give reason
169.
What will be observed
when a burning splint is placed at the mouth of the test tube containing hydrogen gas?
170.
What is the chemical test of hydrogen
gas?
171.
Name the method
or process used to collect hydrogen
gas on its preparation
172.
How is hydrogen
being collected?
173.
Why hydrogen gas is used in filling weather balloons?
174.
Name the drying
agent for hydrogen
gas
175.
On laboratory preparation of
hydrogen gas, dilute sulphuric acid and hydrochloric acid react with some
metals to liberate hydrogen gas. Zinc is the
most suitable metal for the laboratory preparation of hydrogen
gas. Copper (II) sulphate can also be used in this reaction.
a) Why is it possible to collect the gas
i.
By downward displacement of air?
ii.
Over water
b)
What is the use of Copper (II) sulphate in the reaction
c)
Write the word equation for reaction generating hydrogen gas.
d)
Why nitric acid is not used in preparation of hydrogen gas?
e)
Why metals such as as potassium, sodium, lithium and calcium are not usually
used in preparation of hydrogen gas?
f)
Why zinc metal is preferably used in hydrogen
preparation compared to other metals?
g)
Why its difficult to prepare hydrogen
gas using aluminium and magnesium?
h)
Can copper metal be used instead of
zinc metal in preparing hydrogen gas by reacting with dilute
hydrochloric acid?
i)
What does it indicate
when hydrogen gas burns quietly
with blue flame and not pop sound?
j)
What does
it mean by saying hydrogen gas is neutral?
k)
What is the name of a colourles
liquid formed when hydrogen burns in air that
turns white anhydrous copper (II) sulphate blue is formed? Write the
reaction for formation of that liquid?
176.
You have three bottles
without labels, one of which contains a dilute acid. Describe how you could find out which bottle
contained the dilute acid?
177.
When a sample of dry hydrogen
in a test tube is ignited with a flame some droplets
of colourless liquid remain.
178.
When hydrogen is passed over heated lead (II)
oxide, lead is formed
a)
Write a word equation for this
reaction
b)
Use this reaction
to explain the terms oxidation and reduction
179.
Describe how a sample
of hydrogen gas could be prepared and collected from zinc granules?
180.
Hydrogen was once widely used for weather balloons
and airships. Today
weather balloons and airships
are filled with helium.
Explain
181.
Students at KIBO SECONDARY SCHOOL
did an experiment to investigate the effect of
hydrogen on copper (II) oxide basing on the following figure
of illustrations
Questions
i.
Why
is it important to drive out all the air from the combustion tube before lighting the jet?
ii.
State and explain the observation made in the combustion tube.
iii.
Why the supply of hydrogen gas continued while the apparatus cools?
iv.
Write a word equation
for the reaction between hydrogen
and copper (II) oxide.
v.
Why is excess hydrogen
burned and not allowed to escape into the air?
vi.
What is the role of anhydrous calcium chloride?
vii.
What is the use of copper (II) sulphate
in this experiment?
viii.
What would happen if anhydrous calcium chloride
was not used in
this experiment?
ix.
What is the colour
change when copper (II) oxide is heated?
x.
What was the colour of the flame of the lit hydrogen?
xi.
What other substance can be used instead
of anhydrous calcium
chloride?
182.
After collecting hydrogen
gas in the gas jar, its necessary to cover it with a lid. Explain
183.
Comment on the fact that most of
uses of hydrogen are related to its properties. Use six (6) points.
184.
Suppose there were no hydrogen
in the universe. What would happen
185.
Study the diagram
below and answer
the questions that follow:
a)
What is the colour of the solid product?
b)
Name the products
formed.
c)
What is the role of the following
chemicals?
i.
Hydrochloric acid and zinc granules
ii.
Anhydrous calcium chloride
iii.
Cobalt chloride paper
186. Briefly describe
two methods of large-scale production of hydrogen gas?
187. Hydrogen gas is a very promising energy source, yet its uses
as a major source of energy are very limited. Explain this in terms of
its storage, safety and production.
188. State what is observed
when the following
simple experiments are performed
a)
Carbon dioxide gas is passed through lime water for 30 seconds
b)
Water is added to blue cobalt chloride
paper
c)
Water is added to white anhydrous sulphate
d)
A glowing
splint of wood is lowered
into a jar full of carbon dioxide
e)
Iron bar was left
outside for two nights its
colour changed into red-brown
189. Name the two reagents used to prepare hydrogen
gas and write its
reaction.
190. Name the two reagents used to prepare oxygen gas and write its
reaction.
191.
The following figure shows a set – up for the preparation of gas Q in the laboratory
a) Identify gas Q
b) What properties of Q make it possible
to be collected as shown
on the figure?
c)
Describe the
properties of gas Q which relate
with its uses.
192. Gas L has the following properties: it is highly
flammable, readily combines
with other elements, readily reacts with other
chemical substances and is strong reducing
agent.
a) Name the gas L
b)
What method used to collect
gas L in the laboratory? Give reason
c)
Give four
uses of gas L.
193. Suppose that two gas jars: one with
gas A and another
with gas B. Gas a is used in hardening of margarine where as gas
B is used by mountain climbers.
a)
What test will you conduct
to identify each of
the two gases?
b)
Give two physical properties and three chemical
properties that can be used to distinguish gas A from gas B
194. Gas X can be prepared in the laboratory by the decomposition of hydrogen peroxide.
a)
Name gas X
b)
State three physical
properties of gas X
c)
State three chemical
properties of gas X
d)
State three
uses of gas X
195. When dilute
hydrochloric acid is reacted with zinc metal, gas Z is formed
a)
Name gas Z
b)
Mention four physical
properties of gas Z
c)
State two uses of gas Z
196. By giving
one reason, explain
the following facts
i.
Little manganese dioxide is added to hydrogen peroxide
during laboratory preparation of oxygen gas.
ii.
Fish can obtain
oxygen for respiration although they spend their
lives in water.
iii.
Oxygen gas
is used in welding
iv.
Hydrogen is used in production of oxy-hydrogen flame
v.
Hydrogen is used in manufacture of margarine
vi.
Hydrogen is manufacturing of hydrochloric acid
vii.
Hydrogen is used in manufacturing of water gas
viii.
Hydrogen is used in manufacturing of ammonia
197. What is water? Describe
it occurrence and its
nature.
198. State three chemical test for water.
199. Name the products formed
when water reacts with metals.
200. Name four physical properties of water
201. List four chemical properties of water.
202. Why do we
treat water?
203. Explain three
ways on how water can be treated
and purified at home.
204. Explain the ways with the aid of illustration on how urban water
can be treated and purified?
205. why water is important in our daily
lives
206. write short notes on water cycle
207. Explain the importance of the water cycle.
208. How can you test the
purity of the water? Give two
reasons
209. Draw a well labeled
diagram of a sand filter
210. Briefly explain
why water is referred to as
a universal solvent?
211. What colour change is observed when water come into contact
with the following
i.
Red litmus paper
ii.
Blue litmus paper
iii.
White anhydrous copper
sulphate
iv.
Cobalt (II) chloride
212. Explain the importance of the following in water cycle
i.
Evaporation
ii.
Condensation
213. Mount
Kilimanjaro is covered by a mass of ice that makes it important in different aspects. What could happen if the
temperature at the mountain increased beyond its common environmental temperature?
214. Relate the different uses of water to its properties.
215. A
form two student wanted to test the presence of water in an unknown compound using hydrated copper (II) sulphate. A
small amount of hydrated copper (II) sulphate was placed on a watch glass followed by addition of few drops of unknown
compound. There was no colour change observed.
i.
Why there was no change in colour
of hydrated copper (II) sulphate?
ii.
Name two substances that could be used in place of hydrated copper(II) sulphate to observe the required colour change.
216. With the aid of diagram, explain
the processes that take place in the water cycle.
217. Use
the following components to construct a diagram of water cycle: clouds, animal, water in the soil, rain, plants, water
spring, rivers, lakes and water vapour in the
atmosphere.
218. What could happen to living things
if there were no
water?
219. Why water is not used in preparation of oxygen gas in the laboratory although
its composed of hydrogen and
oxygen atoms and its available in larger amount than potassium chlorate
and hydrogen peroxide?
220. Differentiate water
purification and water
treatment
221. Explain five importances
of water purification and treatment.
222. Explain the importance of water
as solvent.
223. Name four types
of natural water.
224. Juma
a villager man who if facing a problem of fetching water at his village since
all water are not different from
muddy water. His friend Mr. quizzer advised him to assemble a small
water filter basing on the
following illustration
Questions
a)
Is the filtered
water different from unfiltered water?
b)
What roles do the cloth,
sand, gravel, charcoal
and beaker play?
225. Why should
drinking water be treated
and purified? Give reasons
226. Why does not
water have effect
on litmus paper?
227. What
would happen to well stoppered bottle full of water left in a deep freezer over night?
Why does this happen?
228. Explain categories of fuels according
to their occurrence with examples
229. Explain categories of fuels according to their physical
state with examples
230. Solid fuels like wood and coal are not recommended or good for use. Explain
with three reasons.
231. What are advantages
over liquid fuels over solid fuels?
Give three reasons
232. What are advantages of fuels with high ignition point?
Give three reasons
233.
Fuels can be categorized according
to their effectiveness (usefulness) or productivity and convenience for use. What are characteristics that are
considered when choosing a good fuel?
234.
Why a good fuel should have moderate (average) ignition point and not low ignition
point?
235.
Fill the following table showing categories of fuels according to their physical
states
|
Physical state |
Primary/natural |
Secondary/artificial |
|
Solid |
|
|
|
Liquid |
|
|
|
gaseous |
|
|
236.
What are environmental effects
of using charcoal
and firewood? Explain
with five points
237.
What are
effects of fossil fuels detrimental to the environment? Give five reasons?
238.
What factors that is important when choosing a fuel? Any seven
239.
What are three
classes of fuel based on their
states and efficiency?
240.
Scientists know that when we use energy, it does
not disappear; it changes
from one form to another.
Briefly explain
a) What law governs this statement?
b)
What are these forms of energy that are
a result of energy transformation?
241.
Give reasons for your answers
in each of the following:
a)
Which two fuels are most appropriate for vehicle engines?
Which other fuels
could be used?
b) Which fuel is most appropriate for space rockets?
c)
Why a coal a suitable
fuel for power station?
242.
Explain the following with examples
a)
Renewable sources of energy
b)
Non –
renewable sources of energy
243.
What do you understand by the term “energy value of the fuel”
244.
Students at YOBWE SECONDARY
SCHOOL did an experiment to determine the enery value of
methanol depending on the following
illustrations
Questions
a)
What is the use
of the calorimeter?
b)
The methanol burner should have a tight lid. Why?
c)
Why should the thermometer not touch the bottom
of the calorimeter while stiring?
245.
Calculate the following questions
246.
(a). Explain why petroleum and coal
are non-renewable sources of energy (b). Give five alternative sources of renewable energy.
247. Explain the working
mechanism of a biogas plant?
248. Describe the energy transformations that take place
in each of the following cases:
a) Energy from the sun is used to generate
electricity for lighting a house
b) Mechanical energy
from waterfalls is used to generate electricity.
c)
A
bicycle wheel is used to burn a dynamo. The electric energy
from the dynamo is used to power a
bulb to produce light.
249. Explain the following in relation to characteristics of good fuel
i.
Energy value of fuel
ii.
Ignition point
iii.
Non combustible materials
iv.
Non hazardous products of combustion
v.
Pyrometric burning
effect
vi.
Affordability
vii.
Availability
viii.
Transportation and storage
ix.
Effects in the environment
250. What are advantages
and disadvantages of gaseous fuel over
liquid and solid fuels? Give two points in each.
251. Why most of villagers at NAMANGONI village
prefer to use firewood and charcoal as the source of fuels?
252. Despite
the policy in Tanzania main land on the use of natural fuel or gas fuel for domestic
activities yet most of people use firewood and charcoal as fuels in their homes?
253. Explain the following
i.
Destructive distillation of fuels
ii.
Destructive distillation of coal (name the product)
iii.
Destructive distillation of firewood/wood (name the product)
254. Describe the properties of different kind of gaseous fuel and their uses.
255. What is matter?
256. In 1803 Dalton developed
the theory about the atom. Write down the five main points
(assumptions/postulates/ideas).
257. Summarize down the findings
of Dalton on the atomic
structure.
258. Write down the ideas of modern concepts of Dalton’s Atomic theory (modifications of
Dalton’s Atomic theory).
259. Draw the model/structure of an atom depending on the following
scientists
i.
Dalton’s model of an atom
ii.
Thomson’s plum pudding
model of an atom
iii.
Rutherford’s planetary model of the atom
260. Give all the sub-atomic particles that make up an atom
and their properties.
261. Give four differences
between the sub-atomic particles of an atom.
262.
Fill the following
table depending on the properties of subatomic particle
|
Sub atomic particle |
symbol |
location |
Charge |
Relative mass |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
263. Explain the meaning of the following terms
i.
Orbits/shells or energy levels
ii.
Orbitals
iii.
Isotopy
iv.
Isotopes
v.
Mass number/atomic mass/nucleon number
vi.
Neutrons
vii.
Protons
viii.
Electrons
ix.
Atomic number
x.
Nucleons
xi.
Electronic configuration/electron arrangement
264. Potassium atom has 19 electrons and the mass number of 39. Work out on the following
i.
Atomic number
ii.
Number of neutrons
iii.
Nucleon number
iv.
Protons number
v.
Give its nuclide
notation
vi.
Representation of the nucleus of the potassium
vii.
Draw its electronic configuration
265. Chlorine has two isotopes
which are 35𝐶𝐿(75%) and 37𝐶𝐿(25%), calculate its relative
17 17
atomic mass of chlorine.
266. Chlorine has two isotopes
which are 35𝐶𝐿(X%) and 37𝐶𝐿(Y%), calculate
its relative
atomic mass of chlorine.
17 17
267. 201𝐽, 206𝐾,207𝐿 and 𝐴𝑀 are isotopes of
element H whose abundance are 2%, 24%, 22% and X% respectively. Calculate the abundance
of X% and mass number
A of isotope M given that the relative atomic mass of
element H is 207.
268. Why relative
atomic masses of some elements
it is not a whole number?
269. Why an atom is said
to be an electrically neutral?
270. Why carbon was chosen
as the standard reference for measuring the atomic masses
of other element?
271. Each
shell can contain only a certain number of electrons, with the maximum being 2n2, what does “n” represent. Calculate
the number of electrons
to be accommodated in K, L, M and
N shells.
272. Define the term periodic
table and modern
periodic table
273. State the three laws governing the periodic table development.
274. Give the weakness or shortcomings of the following who tried to contribute to the development of periodic table.
i.
John newlands
ii.
Dimitri Mendeleev
275. Define the following
terms
i.
Period
ii.
Groups
iii.
Periodicity
276. Fill
the following table according to general trends across the period and down the group.
|
Properties |
Trends across the period |
Trends down the group |
|
Melting point |
|
|
|
Electronegativity |
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Electropositivity |
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Ionization energy |
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Electron affinity |
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Atomic size |
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Reactivity |
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Non metallic character |
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Metallic character |
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Density |
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277. What is the general
name for element
found in group
a) I
b) II
c)
VII
d)
VIII or 0
e)
Between group II and III
278. Answer
the following questions with reference to the first 20 elements in the periodic table
a) Give the chemical symbol
of element having
i.
The smallest atomic size
ii.
The larges atomic size
b) Identify the elements which are
i.
Metals having
3 shells of electrons each
ii.
Metals having
1 electron in the valence shell.
279. Give reasons
on the following
i.
Group one elements
in periodic table
are called alkali
metal
ii.
Group two elements in periodic table are called alkali
earth metal
iii.
Group seven elements
in periodic table are called
halogens
iv.
Group eight elements in periodic table are called noble gases or inert gases.
280. Consider elements
23𝑇 and35𝑄. Which of
the two elements is more electronegative?
11 17
281. What happen
when alkali earth metals burn in oxygen?
282. Write down the physical
properties of alkali
earth metals.
283. Why
thermal conductivities and electrical conductivities of elements decrease
across the periods in periodic table?
284. Give reasons
for the following
I.
Atomic size/radii increase down the
group and decrease across the periods in periodic table.
II.
Electronegativity and ionization energy
decrease down the group and increase across the periods in periodic
table
III.
Melting point decrease down the group and increases across the periods in periodic table.
IV.
Electropositivity increases
down the group and decrease
across the periods
in periodic table.
285. A particular metal reacts slowly
with water to give a strong alkaline solution. In which group
of the periodic table would
you place it?
286. (a) What are noble/gases?
(b) In which group of periodic table do the noble gases belong?
(c) What is common about
the noble gases regarding the following properties?
i.
Electronic arrangements
ii.
Chemical reactions
287. (a) Given the elements
calcium, sulphur, chlorine, helium and neon, write down their
i.
Period numbers
ii.
Group numbers
iii.
Atomic numbers
iv.
Number of electrons
in one atom
v.
Electronic configuration
(b). Which of the above
elements would you expect to have simiral
properties. Give reasons.
288. Give five examples of metalloids
289. The following
diagram represents the periodic table with four areas
denoted by 1, 2, 3, and 4
Questions
i.
Which area is most likely to contain
non-metals?
ii.
Which area is most likely
to contain elements
whose oxides dissolve in water?
iii.
Which area contains
transition elements?
iv.
Which area is most likely
to contain elements with both metallic
and non-metallic characteristics?
290. The diagram
below show the structures
of atoms of elements X and Y:
i.
Which one is stable?
ii.
Which of the two elements
conduct electricity?
iii.
Which of the two elements
is chemically more reactive? Explain
iv.
Identify elements
X and Y.
