CHEMISTRY NECTA GUIDING 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
QUESTIONS
i.
What was the aim of the experiment?
ii.
What type of solution is formed when a spatulaful of
table salt was dissolved in 100cm3?
Explainwith reason
iii.
What type of solution is obtained ate room temperature
when no more salt can dissolve? Explain with reason
iv.
What name is given to the final solution? 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
266. Chlorine
has two isotopes which are
267.
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
|
|
|
|
Electropositivity
|
|
|
|
Ionization
energy |
|
|
|
Electron
affinity |
|
|
|
Atomic
size |
|
|
|
Reactivity
|
|
|
|
Non
metallic character |
|
|
|
Metallic
character |
|
|
|
Density
|
|
|
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
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
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.
