TIME: 2:30 HOURS
INSTRUCTIONS
·
This paper consists of sections A and B.
·
Answer all questions in all section.
·
All writings must be in blue or black
ink except drawings which must be in pencil.
·
Calculators, cellular phones and any
unauthorized materials are not allowed in examination room.
·
Write your examination number on every
page of your answer sheet provided.
·
Atomic masses of some elements are as
follows:
(Al = 27, C =
12, N = 14, O = 16, H = 1 and Na =23)
SECTION
A (20 MARKS)
Answer
all questions in this section
01. For
each of the items (i) – (x), choose the most correct answer from among the
given alternatives and write its letter in the answer sheet provided.
i)
Which of the following are the main
components of a fire triangle?
a) Air,
temperature and fire b) Oxygen, temperature and fuel
c) Oxygen, heat
and fuel d) oxygen, temperature and fire [
]
ii)
The process of coating iron or steel
with zinc is known as:
a) Zinc plating b) Alloying c) Tin plating d) Galvanization [ ]
iii)
Why is the fractional distillation of
coal done?
a) To remove
oxygen in the atmosphere b) To remove
volatile matter
c) To add oxygen
in the furnace d) To add
volatile matter [ ]
iv)
Which of the following are the states of
matter?
a) Gas, liquid
and mixture b) Gas, liquid and solid
c) Elements,
compounds and mixtures d) Elements,
mixture and gas [ ]
v)
The electronic configuration of Argon
is:
a) 2:8:6 b) 2:7:5 c) 2:8:7 d)
2:8:8 [ ]
vi)
The percentage composition of nitrogen
in NH4NO3 is ____ %.
a) 28.70 b) 25 c)
35 d) 14.50 [ ]
vii)
The empirical formula of a certain
compound is CH3. Its molecular mass is 30 g. what will be its
molecular formula?
a) C4H12
b) C2H8
c) C2H4 d) C2H6 [ ]
viii)
Which of the following is not true about
hydrogen?
a) It is lighter
than air b) It is
odourless
c) It burns with
a blue flame c) It supports
combustion [ ]
ix)
What happen when iron metal surface
under goes rusting?
a) Fe is
oxidized
b) Fe is reduced c) Fe is anodized d) Fe is electrolysed [ ]
x)
Water is:
a) Acidic b) Basic
c) Neutral d) Both acidic and basic [ ]
02. (a)
Match each item in LIST A with a correct response in LIST B by writing the letter
of the correct response below the corresponding item number in your answer
sheet.
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LIST
A |
LIST
B |
|
i)
It occurs between two ions with
opposite charges ii)
It involves the sharing of electrons
between atoms iii)
Shows the simplest ratio of atoms or
ions in a compound iv)
Shows the actual number of each atom
in a molecule v)
A force of attraction that holds atoms
together to form a molecule |
A.
Cation B.
Anion C.
Valency D.
Electrovalent bond E.
Covalent bond F.
Empirical formula G.
Molecular formula H.
Chemical bond |
02. (b)Fill in
the blank spaces with the correct answer.
i)
A chemical process that occurs in steel
and iron in the presence of air and water is knowns as _________________
ii)
Oxygen, heat and fuel are the three
components that make _________________
iii)
The process of extinguishing harmful
fire is _________________
iv)
A solution which can dissolve no more
solute at a given temperature is called _________________
v)
Group two elements of the periodic table
are called _________________
SECTION
B (80 MARKS)
Answer
all questions in this section
03. (a)
Give five (5) importance of Fist Aid
(b) Give three
(3) reasons to why, Bunsen burner is the most used source of heat in the
laboratory.
04. (a)
Define the following terms
(i)
Element ii)
Compound
(b) Identify
whether the following is a physical or chemical change:
i) Cutting
aluminium foil into pieces ________________________
ii) Lighting a
match __________________________
(c) How can you
separate the following mixtures?
i) Water and
kerosene ii)
Salt and water
iii) Ethanol and
water iv)
sand and Iodine
05. (a)
Write fours sources of energy used for cooking in most Tanzanian societies.
(b) List any
four characteristics of a good fuel
06. (a)
Define the following terms
i) Valency ii)
Anion
iii) Oxidation
state iv)
Cation
(b) Calculate
the oxidation state of the underlined elements in the following radicals:
i) NH4+
ii) SO42-
iii) ClO3-
07. (a) Define
the following terms
i) Empirical
formula ii)
Molecular formula
(b) A compound
consists of 40% carbon, 6.67% hydrogen and 53.3% oxygen. If its relative
molecular mass is 60, calculate:
i.
Empirical formula
ii.
Molecular formula
08. (a)
Using a large well labelled diagram, show the laboratory preparation of
hydrogen from zinc granules and dilute hydrochloric acid.
(b) Write a word
and chemical equations for the reaction taking place in 8(a) above.
(c) Give four
uses of hydrogen gas
09. (a)
Write the chemical formula of each of the following compounds
i) Iron (II)
sulphate
ii) Magnesium phosphate
iii) Sodium
hydrogen carbonate iv)
Ammonium sulphate
(b) Write two
chemical properties of water.
10. Study
the table below and answer the questions that follow:
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A |
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B |
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C |
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D |
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E |
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QUESTIONS:
i)
Write letters for the elements called
Alkali metals ____________
ii)
Write electronic configuration for the element
represented by letter D _______
iii)
Which letter represents zero group
element?
iv)
In which group and period does the
element represented by letter E belong?
