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PAPER ONE TYPE OF QUESTIONS
1. Which changes, A, B, C or D can involve both
condensation and freezing?
5. A mixture of two sugars was compared with 4
2. Three substances have the following properties
different sugars using chromatography.
The results are shown in the figure below

Substance 1 is brittle

Substance 2 melts at 5°C and boils at 250°C

Substance 3 has a high melting point of 800°C
What is the state of each substance at room
temperature and pressure?
Subst 1
Subst 2
Subst 3
A. Gas
Liquid
Solid
B. Solid
Gas
Solid
C. Solid
Liquid
Solid
Which two sugars does the mixture contain?
D. Solid
Gas
Gas
A. 1 and 2
B. 1 and 4
C. 2 and 3
D. 2 and 4
3. The diagram below shows apparatus being used to
distil sea water. At which point is the temperature
100°C?
6. The diagram below shows a chromatogram which
was prepared using spots of five different inks.
How many different dyes were used to make the
five inks?
A. 3
4. The diagram shows a mixture of water alcohol
B. 4
being separated by distillation.
C. 5
Where are the molecules furthest?
D. 12
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7. Which of the following gases diffuses fastest under
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11. Which diagram below shows the arrangement of
the same conditions of temperature and pressure?
particles inside a balloon filled with a mixture of
A. Chlorine
helium and argon?
B. Carbon dioxide
C. Methane
D. Sulphur dioxide
8. Which method is used to obtain pure water from a
solution of sugar?
A. Chromatography
B. Crystallization
C. Distillation
D. Filtration
9. Bromine has a melting point of –2°C and a boiling
point of 59°C.
At which temperature is bromine a liquid?
12. Liquid X and liquid Y can be separated by
fractional distillation . Which of the following can
be deduced from this statement? The liquids
10. A student titrated 25.0 cm3 of an alkali with an
acid.
The figure below shows the acid level in the burette
at the start and end of the titration.
A. Are immiscible
B. Have covalent bonds
C. Have different boiling points
D. Have different densities
13. The diagram shows some laboratory apparatus.
What volume of acid was added from the burette?
A. 25.8 cm3
B. 26.6 cm3
C. 27.4 cm3
D. 28.2 cm3
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Which apparatus are needed to produce and
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17. Which of the following statements about
collect pure water from seawater?
endothermic reactions are correct?
A. 1, 2 and 4
B. 1, 4 and 5
(i)
Energy is released to the surroundings.
C. 2 and 5
D. 3 and 5
(ii)
Energy is absorbed from the surroundings
(iii)
The temperature of the surroundings rises.
(iv)
The temperature of the surroundings falls.
14. Which piece of apparatus is used to measure
exactly 22.5 cm3 of a liquid?
A. (i) and (ii)
B. (ii) and (iii)
C. (i) and (iv)
D. (ii) and (iv)
18. What is always produced during photosynthesis?
A. Carbon dioxide
B. Methane
C. Oxygen
D. Water vapour
15. Which piece of apparatus would be most suitable
19. The formation of liquid water from hydrogen and
to measure accurately the volume of acid needed
oxygen occurs in THREE stages.
to neutralize 25.0 cm3 of an alkali?
STAGE 1: 2H2 (g) + O2 (g) → 4H (g) + 2O (g)
STAGE 2: 4H (g) + 2O (g) → 2H2O (g)
STAGE 3: 2H2O (g) → 2H2O (l)
Which stages are endothermic?
A. 1 only
B. 2 only
C. 3 only
D. 1, 2 and 3
20. The table shows information about ions Q and R.
16. Potassium nitrate crystals can be separated from
ion
Protons
neutrons
electrons
Q
16
16
18
R
17
18
18
What are ions Q and R?
sand by using the processes shown.
A. negative ions of different elements
What is the correct order for the processes?
B. negative ions of the same element
first
A Filter
B Dissolve
C Dissolve
D Dissolve
→
last
Dissolve
Evaporate Crystallize
Evaporate Crystallize Filter
Evaporate Filter
Crystallize
Filter
Evaporate Crystallize
C. positive ions of different elements
D. positive ions of the same elements
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21. The table shows the number of protons, neutrons
and electrons in four ions. For which ion is the data
correct?
ion
A
40
20
Ca 2
protons
20
B
19
9
F-
9
10
8
C
18
8
O 2-
10
8
12
D
23
11
11
12
10
Na

neutrons
20
electrons
20
22. A substance contains the ions X4+ and Y2–. What is
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26. The atoms
31
15
P and
32
16
S have the same
A. nucleon number
B. number of electrons
C. number of neutrons
D. number of protons
27. The nuclei of the atoms
64
29
Cu and
65
30
Zn have the
same
A. nucleon number (mass number)
the simplest formula of the compound containing the
B. number of electrons
ions X4+ and Yˉ?
C. number of neutrons
A. XY2
D. proton number(atomic number)
B. X2Y
28. It is now known that one form of carbon has
C. X2Y4
molecules of formula C60. What is the relative
D. X4Y2
molecular mass, Mr, of these molecules?
23. The elements X and Y form the compound X2Y.
A. 12
What is the correct electronic configuration of the
B. 60
atoms X and Y?
C. 360
Electronic Configuration
Atom of X
D. 720
Atom of Y
A. 2, 1
2, 7
B. 2, 2
2, 7
C. 2, 1
2, 6
D. 2, 2
2, 6
29. The figure shows the arrangement of electrons in
the outer shells of the atoms in the compound YZ2.
24. Two of the isotopes of oxygen are 16O and
18O.The
difference between these two is in the
number of …
A. electrons
B. neutrons
Which pair of elements could be Y and Z?
C. protons
Y
D. shells
25. An atom of argon has 18 electrons. Which of the
following ions does not have 18 electrons?
A. Ca2+
B. Cl–
C. K+
D. O2–
Z
A. calcium
fluorine
B. carbon
sulphur
C. oxygen
hydrogen
D. sulphur
chlorine
30. Which diagram shows the structure of a 73 Li atom?
key: p=protons; n=neutrons; e=electrons
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A graph of the balance readings against time was
plotted. Which curve was obtained?
31. Which of the following is not a covalent compound?
A. methanol
B. zinc chloride
C. ammonia
D. carbon tetrachloride
32. What is the mass of oxygen contained in 72g of
pure water?
A. 16g
35. Two experiments were carried out using the
apparatus shown in the figure below.
B. 32g
C. 64g
D. 70g
33. Iron and nitrate ions combine to form iron (III)
nitrate. The formula of the compound formed is ...
A. Fe(NO3)3
B. Fe2(NO3)3
C. Fe3NO3
D. Fe3(NO3)2
34. The experiment shown was set up and the balance
was read in intervals.
In experiment 1, dilute hydrochloric acid was used.
In experiment 2, concentrated hydrochloric acid
was used.
All other conditions were the same and in both
experiments all the marble chips had completely
reacted. Which one of the graphs below shows the
results obtained?
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B. 4.000 g
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C. 4.600 g
D. 3.200 g
39. 40g of magnesium oxide were obtained by
burning 24g of magnesium in excess oxygen as
shown in the reaction equation below. How much
oxygen was used in the reaction?
2Mg + O2 → 2MgO
A. 16g
B. 32g
Key
_________ Experiment 1
-------------- Experiment 2
36. Substance P
C. 48g
D. 80g
40. How many tonnes of aluminium oxide, Al2O3, are
(i)
has a high melting point
required to produce 27 tonnes of aluminium?
(ii)
is a good conductor of electricity
A. 54.0
(iii)
is malleable
B. 27.0
What could P be?
C. 51.0
A. graphite
D. 102
B. iron
C. silicon (IV) oxide
D. sodium chloride
41. Which of the following contains the same number of
molecules as 9g water?
A. 2g of hydrogen gas
37. The maximum number of electrons in a shell whose
B. 14g of nitrogen gas
position from the nucleus is numbered ‘n’ is
C. 32g of oxygen gas
determined by the formula…?
D. 44g of carbon dioxide
A. n2
B. 2n
42. What is the ratio of the volume of 2g of hydrogen
C. 2n2
to the volume of 16g of methane, both at r.t.p?
D. 2n - 2
A. 1 to 1
B. 1 to 2
38. Magnesium burns in oxygen according to the
following equation.
C. 1 to 8
D. 2 to 1
2Mg(s) + O2(g) → 2MgO(s)
If 2.4 g of magnesium burns completely in oxygen,
what mass of magnesium oxide will be produced?
A. 40.00 g
43. The equation for the reaction between calcium
carbonate and hydrochloric acid is shown below:
CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O + CO2(g)
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How many moles of calcium carbonate will give 24
cm3 carbon dioxide measured at r.t.p. when
48. Which atom forms an ion with a charge of 2+?
reacted with an excess of the acid?
atomic number
A. 1.00 mol
A.
6
B. 0.10 mol
B.
8
C. 0.01 mol
C.
12
D. 0.001 mol
D.
15
44. An 8g sample of oxygen contains the same number
49. In a chemical reaction , a catalyst increases the rate
of atoms as 16g of element X. What is the relative
of reaction by …
atomic mass of X?
A. Lowering the energy barrier
A. 4
B. Increasing frequency of collisions between
B. 8
particles
C. 16
C. Raising the energy of activation
D. 32
D. Making the reaction exothermic.
45. The equation shows a chemical reaction between
sodium and water. The equation is not balanced.
50. Copper (ii) oxide is changed to copper according
xNa + yH2O → 2NaOH + H2
to the equation below.
What are the values of x and y?
CuO + H2 → Cu + H2O
x
y
In this reaction …
A. 1
1
A. Copper (ii) oxide is oxidized.
B. 1
2
B. hydrogen is the oxidizing agent.
C. 2
1
C. Copper (ii) oxide is reduced.
D. 2
2
D. hydrogen is reduced.
46. Which molecule contains double covalent bonds?
A. Carbon dioxide
PAPER THREE TYPE OF QUESTIONS
B. Chlorine
1. Paper chromatography was used to investigate a series
C. Hydrogen Chloride
of dyes A, B, C, D, E, F and G. The resulting
D. Methane
chromatogram is shown below:
47. Which pair of properties is typical of a covalent
compound?
Melting
Conductivity of aqueous
Point/°C
solution
A
120
does not conduct
B
120
conducts
C
1610
does not conduct
D
1610
conducts
(a) Suggest the name of a suitable solvent
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(b) Which dyes are pure substances?
(c) Which two dyes are the same?
(d) Which dye is a mixture of C and E?
2. A sample of water contains salt as an impurity. The
apparatus below is used to produce pure water from
the sample.
(a) (i) Draw a labeled diagram of apparatus that can
be used in the laboratory to separate the pieces of
crushed cane from the sugar solution.
(ii) Explain why the sugar in solution is not
separated out by the apparatus described in (i).
(iii) For the sugar to be crystallized, the solution is
concentrated. How can the solution be
concentrated?
(a) (i) Name the method of purification.
(ii) Suggest the purpose of the water jacket.
(b) If the pure sugar is dissolved in water, mixed with
yeast and left to react, ethanol is formed.
(b) What would be the approximate reading on the
thermometer during the purification?
(c) Draw a cross (×) on the figure where the salt would
(i)
What is the name of this process?
(ii)
What observation shows that a chemical
reaction is taking place?
be left after purification is complete
(iii)
boiled?
3. Some countries grow sugar cane from which sugar is
extracted. The sugar can be extracted on a laboratory
Why must the reacting mixture not be
(c) The solution from (b) contains ethanol and water.
scale by cutting the cane into pieces, crushing it and
Name the process used to separate these
stirring it with water to dissolve as shown in the figure
substances.
below.
4. The figure below shows four compounds K, L, M and N.
compound
state at
approx.
electrical
20°C
B.P. /°C
conductivity of
molten compound
K
Gas
–25
poor conductor
L
Solid
5000
poor conductor
M
Solid
1500
good conductor
N
Liquid
25
poor conductor
(a) Particles of solids behave differently from particles
of gases. Give three differences in behaviour.
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(b) Write the letters of two compounds in the table
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substance
above that
diagram
(i) are gases at a temperature of 30°C
A–F
copper
gas
mixture
hydrogen
water
(ii) consist of simple molecules
(c) (i) Suggest how the atoms are bonded in compound 7. Suggest why
(a) a solid has more mass than the same volume of gas;
M and compound N.
(ii) Suggest why compound M has a higher boiling
(b) a gas is easier to compress than a solid;
point than compound N.
(c) a gas, at constant pressure, increases greatly in
volume when it is gently heated, but a solid does
not;
5. The table below shows some properties of several
(d) a liquid takes the shape of its container but a solid
different substances.
substance
A
B
C
D
melting
point/°C
-259
1083
808
decomposes
solid
substance
conducts
electricity
no
yes
no
no
liquid
substance
conducts
electricity
no
yes
yes
no
does not;
(e) a liquid perfume can be smelled at some distance
from the liquid.
8. Use your knowledge of the kinetic particle theory to
suggest a reason for each of the following:
(a) wet clothes dry more quickly on warm days than
Which one of the substances in the table consists of:
cold days.
(a) ions
(b) solid ice loses its shape when it melts.
(b) small, covalently bonded molecules
(c) sugar dissolves faster in hot water than in cold
(c) macromolecules
water.
(d) metal atoms
(d) when salt is dissolved in a glass of water without
stirring, all of the water soon tastes salty.
6. The drawings below represent particles in six different
substances at room temperature and pressure.
9. Some properties of four solids, I, J, K and L are given in
the table below.
solid
%
composition
by mass
solid
conducts
electricity
strong heat
in air
I
constant
no
decomposes
J
varies
no
burns
K
varies
Yes
melts
L
constant
yes
oxides to
Complete the table below to show which one of the
one
drawings A to F, best represents each of the following
substance
element
or mixture
or
compound
substances.
You may use each letter once, more than once or not
at all.
10. (a) Uranium is used in nuclear reactors. A sample of
uranium is found to consist of two isotopes.
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Study hard
(i)
Define isotopes
decomposition of sodium azide.
(ii)
The table below describes two isotopes of
uranium. Complete the table.
Isotopes
No. of
protons in
each atom
92
No. of
neutrons in
each atom
143
Symbol
of
isotope
reactor. Naturally occurring boron contains atoms
represented by the symbols
(i)
(b) In a crash an air-bag fills 72cm3 of nitrogen at room
temperature and pressure.
Uranium
– 235
233
Uranium
92 U
– 233
(b) Boron is used to make control rods for a nuclear
10
5
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What mass of sodium azide is needed to provide the
nitrogen?
(c) Sodium azide, NaN3, reacts with dilute hydrochloric
acid to give sodium chloride and a compound nitrogen
hydride.
Construct the equation for the reaction between sodium
azide and dilute hydrochloric acid.
11
5
B and B
Draw a diagram of the electronic structure of a
13. (a) Atoms with two electrons in their outermost shell can
boron atom.
(ii)
Suggest why the relative atomic mass of
combine with atoms with seven electrons in their
naturally occurring boron is not a whole
outermost shell. Draw ‘dot and cross’ diagrams to show
number.
such a combination. Name the atoms and the compound
formed.
2
11. An atom of calcium, 40
.
20 Ca , forms a calcium ion, Ca
The ion contains protons, neutrons and electrons
(a) Complete the table below to describe the particles
in the calcium ion.
particle
number in one
proton
positive charge
neutron
molten ionic compounds will conduct
electricity.
(ii)
Solid ionic compounds will not conduct
electricity.
14. When non-metals such as hydrogen and chlorine
combine, they form covalent bonds.
(a) What are covalent bonds?
electron
(b) Why do some covalent compounds have low boiling
(b) How does the formation of calcium ion show that
calcium is a metal?
(c) How will another isotope of calcium
(ii)
(i)
electrical charge
Ca2+ ion
(i)
(b) Explain why
differ from
40
20
Ca ?
be the same as
40
20
Ca ?
12. Many cars are fitted with air-bags which inflate in an
accident. Air-bags contain the solid azide, NaN3, which
decompose rapidly to form sodium and nitrogen. The
nitrogen formed fills the air-bag.
(a) Construct the equation, including state symbols, for the
points?
15. A metal, lithium reacts with air and water.
(a) Suggest how lithium should be stored.
(b) A student reacted lithium with water using the
apparatus shown below.
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(ii) What ions, present in this solution, cause this
change?
16. Sodium sulphate forms a colourless, neutral solution
when mixed with water.
(a) Describe how this solution can be prepared in the
laboratory from a named acid and alkali. Write a
chemical equation including state symbols for the
reaction.
The student measured the volume of gas at
intervals of 30 seconds. The results are shown in the
table below.
time/s
0
30
60
90
120
150
volume/cm3 0
40
60
74
86
96
Plot a graph of these results on the grid below. Use
(b) Sodium sulphate crystals have the formula
Na2SO4.10H2O.
Calculate
(iii)
the relative molecular mass of sodium
sulphate crystals.
(iv)
the percentage by mass of water in the
crystals.
the vertical axis to plot volume
17. Germanium, Ge, is extracted from germanium (IV)
oxide by heating with hydrogen. This is the unbalanced
chemical equation for the reaction.
GeO2 + H2 → Ge + H2O
(a) Balance the above chemical equation
(b) During this reaction hydrogen removes oxygen from
germanium (IV) oxide. What is the name given to
(c) Tick in the box below to show when the rate of
reaction was greatest
at time/s
the change of germanium (IV) oxide to germanium?
(c) Using the appropriate atomic masses
5
35
65
95
125
(i)
greatest rate of reaction
(d) How can the student find the time taken for the
calculate the percentage by mass of
germanium (IV) oxide
(ii)
reaction to stop?
Calculate the smallest mass of germanium
(IV) oxide needed to produce 300 g
(e) The temperature of the water increased during the
germanium by this reaction.
reaction. How would you classify the reaction?
(f) (i) Name the gas liberated in this reaction.
18. Potassium superoxide, KO2, is an ionic solid. It can be
(ii) Describe a test to confirm the presence of this
used in spacecraft to supply oxygen according to the
gas.
following equation.
(g) (i) Universal Indicator is added to the solution in the
trough at the end of the experiment. What colour
will you see?
4KO2(s) +2H2O→4KOH(s) +3O2 (g)
The potassium hydroxide formed removes carbon
dioxide.
(a) Show that 1.0g of potassium superoxide will supply
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Study hard
about
0.25dm3 of
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oxygen at room temperature and 20. (a) What is meant by molar gas volume and what is
pressure.
(b) (i) Name the compound formed when carbon
dioxide reacts solid potassium hydroxide.
(ii) Give the equation for the formation of this
compound.
(c) Supplies of oxygen in hospitals are stored in
cylinders.
(i) State one other use of oxygen.
its value for carbon monoxide at r.t.p.?
(b) Hydrogen gas burns in oxygen gas to form water.
Construct an equation for the reaction and calculate
(i)
the volume
(ii)
the mass
of oxygen needed to burn 24 dm3 of hydrogen, all
volumes being measured at room temperature and
pressure.
(ii) Describe briefly how oxygen is obtained from
air.
21. (a) Copper (II) sulphate solution acts as a catalyst in the
reaction of zinc and dilute sulphuric acid. A gas is
produced by the reaction.
19. Details of the chlorides of elements in period 3 of the
periodic table are shown in the table below:
group
no. of
I
II
III
IV
V
VI
element
formula
of
NaCl CaCl2 Al2Cl6 SiCl4 PCl5 S2Cl2
chlorides
approx.
melting
810 780
180
–70 160 –80
point/°C
(a) (i) Name the chloride in Group II.
(i)
What gas is produced?
(ii)
What is meant by a catalyst?
(iii)
How will the presence of a catalyst affect
the time it takes for the reaction to stop?
(iv)
Give a reason for your answer to (iii)
above.
(b) The apparatus in the figure below is used to
investigate how the changes in temperature affect the
activity of the catalyst in the above reaction.
(ii) How many atoms of chlorine are present in a
molecule of silicon tetrachloride?
(iii) Write down the formulae of the chlorides in the
table above which are not solids at 20°C.
(iv) Write down the formulae of the chlorides in the
table above which are ionically bonded. Use the
data in the table to explain why you believe that
they are ionically bonded.
(b) (i) Chlorine has a proton number of 17. Sodium has
a proton number of 11. Draw a ‘dot and cross’
diagram to show the electronic structure of sodium
chloride.
Complete the figure above to show how to
(ii) Explain why molten sodium chloride conducts
(i) add a solution of the catalyst to the flask,
electricity.
(ii) collect the gas being produced and measure its
volume.
(c) Why is the water bath needed?
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Study hard
(d) List three measurements you would take.
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(iii) Heat the solution using the hot water bath until half
The End
its volume and cool the hot saturated solution to
obtain sugar crystals.
POSSIBLE SOLUTIONS TO THE PROBLEMS
(b) (i) Fermentation
(ii) Effervescence occurred; bubbles of colourless
Paper one type of answers
1
C
11
A
21
D
31
B
41
B
2
C
12
C
22
A
32
C
42
A
3
B
13
B
23
C
33
A
43
D
4
B
14
B
24
B
34
D
44
D
5
D
15
A
25
D
35
C
45
D
6
B
16
D
26
C
36
B
46
A
7
C
17
D
27
C
37
C
47
A
8
C
18
C
28
D
38
B
48
C
9
B
19
A
29
D
39
A
49
A
10
B
20
A
30
A
40
C
50
C
Paper three type of answers
gas evolved forming a layer of foam on the
surface of the solution.
(iii) Boiling denatures enzyme zymase (in yeast)
and kills the yeast cells.
(c) Fractional distillation
4. (a)
1.
in a closed packed structure.
2.
(c) Substance B and G
(d) Substance D
The particles in a solid can only vibrate in a
fixed position and cannot move randomly in
1. (a) Ethanol
(b) Substance A and F
The particles in a solid are arranged orderly
all directions.
3.
The spaces between particles in a solid are
negligible. They are in close contact
compared to gas particles which are far
apart from each other.
2. (a) (i) Simple distillation
(ii)To condense steam distilling over into water.
(b) 100°C
(b) (i) gas K and gas N
(ii) gas K and gas N
(c) (i) M: ionic bond, transfer of electrons from metal to
(c) The cross should be drawn at the bottom of the flask.
non-metal to form positive and negative ions.
That is where the salt would be left after purification.
N: covalent bonds, sharing of electrons between
two or more non-metal atoms.
3. (a) (i)
(ii) Compound M has strong electrostatic forces of
attraction between the opposite charged ions that
are regularly arranged in the ionic lattice. A large
amount of energy is required to break these strong
forces of attraction before the ions can move out of
its fixed position and melt to form a liquid.
Compound N has weak intermolecular forces of
attraction between its molecules. Less energy is
required to break these weak forces of attraction.
(ii) Sugar dissolves in water. Sugar molecules are small
enough to pass through the pores of the filter
paper.
5. (a) substance C
(b) substance A
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Study hard
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(c) substance D
attraction giving its shape. When ice melts, the water
(d) substance B
molecules break away from the regular closed packed
structure, mover further apart and move randomly
throughout liquid water.
6.
substance
Copper
gas
mixture
hydrogen
water
(c) The heat in the hot water provides more energy
diagram
A–F
A
E
F
E
C
required for the intermolecular forces of attraction in
7. (a) In a solid, the particles are held very closely
together in a regular pattern whereas in a gas, the
particles are widely separated and move randomly at
great speeds. Thus, there are many more particles
packed into a solid compared to the same volume of
gas
(b) A gas consists of particles that are widely
the sugar molecules to break faster and occupy the
spaces between water molecules.
(d) Sodium chloride crystals dissolve to form sodium ions
and chloride ions. These ions move from a region of
higher concentration (region surrounding salt crystals) to
a region of lower concentration (the rest of the water)
by diffusion, until all the ions are uniformly distributed
throughout the solution.
separated compared to the closely packed particles in
a solid. Applying a pressure on a gas causes the gas
9. I ─ compound
particles to move closer together, reducing the space
J ─ mixture
between the particles resulting in a decrease in the
K ─ mixture
volume.
L ─ element
(c) When gas particles are heated, they absorb energy
and move faster because they possess more kinetic
10. (a) (i) Isotopes are atoms of the same element with the
energy. The gas particles move farther apart and
same atomic number but different number of neutrons,
become more widely separated than before. Thus, the
hence different mass numbers.
same number of gas particles occupies a larger volume
(ii)
when heated.
Isotopes
(d) In liquids, the particles are packed more closely
together than in a gas but they are free to move
randomly throughout the liquid and spread out to fill
any container it is poured in.
(e) Liquid perfume, a volatile liquid, forms vapour
Uranium
– 235
Uranium
– 233
(b) (i)
No. of
protons in
each atom
92
No. of
neutrons in
each atom
143
Symbol of
isotope
235
92
U
92
141
233
92
U
readily in air. The perfume molecules collide with the
air molecules and move throughout the air. They diffuse
from a region with a higher concentration of perfume
molecules to a region of lower concentration.
(ii) The relative atomic mass of an element is the
8. (a) The rate of evaporation of water increase with
weighted average of the masses of the atoms
higher temperatures.
(isotopes) in a naturally occurring sample of the
(b) The water molecules in ice are closely packed in a
element.
regular lattice with strong intermolecular forces of
- 16 -
Study hard
Ar boron=
(% of
10
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B  10)  (% of B  11)
100
11
11. (a) See the table below
number in one Ca2+ ion
electrical charge
proton
20
positive charge
neutron
10
no charge
electron
18
negative charge
(b) (i) Molten ionic compounds contain free mobile ions
to conduct electricity.
(ii) In solid state, ionic compounds have strong
electrostatic forces of attraction between the
opposite charged ions that are regularly arranged
(b) Calcium atom lost 2 valence electrons to form
in fixed positions in the ionic lattice. Therefore,
Ca2 ions. Metal atoms have 1, 2 or 3 valence electrons
there are no free mobile ions to conduct electricity.
and have a tendency to lose their valence electrons to
achieve a stable configuration.
14. (a) Covalent compounds are formed when non-metallic
(c) (i) Number of neutrons.
atoms achieve stability by sharing a pair of electrons in
(ii) Same number of protons and electrons.
their outer shells, one from each atom.
(b) Covalent compounds generally have weak
12. (a) 2NaN3(s)→2Na(s) +3N2(g)
intermolecular forces of attraction between their
molecules. Only a small amount of energy is required to
(b) 1 mole of nitrogen → 24dm3
break these weak forces of attraction
3 moles of nitrogen → 72dm3
Mole ratio from equation in (a)
2mole NaN3
X
X
_______ 3moles
______
==
15. (a) Lithium metal is stored in oil.
N2
(b) See the graph below!
3moles N2
2moles NaN3
Mass = mole x molar mass
=2molesx65g/mol
=130g.
(c) NaN3 + HCl→ NaCl +N3H
13. (a) The atom with two valence electrons must be a
metal from Group II. It could be magnesium metal. The
atom with seven valence electrons is a non-metal from
Group VII (halogens) e.g. chlorine. Ionic bonds are
formed when magnesium atom transfers its 2 valence
electrons to 2 chlorine atoms. Ionic bonds are strong
electrostatic forces of attraction between the
magnesium and chloride ions.
(c) the greatest rate of reaction is during the 5th second. So
the tick should be placed in the column for 5th second.
(d) The time taken for the reaction to stop is the period from
the start of the experiment to the time when the volume of
hydrogen gas collected remained constant i.e. when the
graph levels off or when the graph has a zero gradient.
(e) Exothermic reaction
(f)
(i) Hydrogen
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Study hard
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(ii) Place a lighted splint on the mouth of the test
tube of the gas collected. The lighted splint burns
with a ‘pop’ sound
(g)
19. (a) (i) calcium chloride
(i) The universal indicator turned blue.
(ii) hydroxide ions, OH

(ii) 4 chlorine atoms
(iii) SiCl4 and S2Cl2
(iv) Formulae: NaCl and CaCl2
16. Acid : dilute sulphuric acid.
Explanation: They are ionic compounds with very
Alkali :sodium hydroxide
high melting points. A lot of energy is required to
An indicator e.g methyl orange.
break the strong electrostatic attraction between
The above substances are reacted according to the
metal ions and chloride ions in the crystal lattice
(b) (i)
following equation:
2NaOH(aq)  H2 SO4 (aq)  Na2 SO4 (aq)  2H 2O(l)
The indicator changes from yellow to orange .The
resultant mixture is heated until saturated and cooled to
allow crystallization. The crystals are removed by
filtration.
(ii) Molten sodium chloride contains free, mobile
(b) (i) R.M.M. 2(23)  4(16)  10(18)  322 g/mol
sodium and chloride ions that conduct electricity.
(ii) % of water 
10(18)
 100  55.9%  56%
322
20. (a) Molar gas volume is the volume occupied by one
mole of gas. At room temperature and pressure (r.t.p.),
17. (a) GeO2 (s)  2H 2 (g)  Ge(s)  2H 2 O(l)
(b) Reduction
73
(c) (i)
 100  69.5%
73  2(16)
100
(ii) 300 
 432 g
69.5
18. (a) mass of KO2 =71g. mass of 4moles of KO2=284g
which will give 3 moles x 24dm3 =72dm3 of O2 at
r.t.p
the molar gas volume of carbon dioxide is 24dm3 or
24000 cm3
(b) (i) Equation for reaction: 2H2(g) + O2(g) → 2H2O(l)
From the equation, 1 mole of O2 reacts completely
with 2 moles of H2 gas, therefore, volume of O2
required to burn 24cm3 of H2 (i.e. 1 mol H2) is
1
 24 dm3  12 dm3
2
(ii) R.M.M. of O2=32
Mass of O2 required =
284g KO2 ______ 72dm3 O 2
1.0g
12
 32  16 g
24
________ X
X = 0.25dm3 hence shown.
(b) (i) Potassium carbonate
(ii) CO2(g) + 2KOH(s)→ K2CO3(s) + H2O(l)
(c) (i) combined with acetylene in welding.
(ii) Oxygen is obtained by fractional distillation of
liquid air.
21. (i) Hydrogen
(ii) A catalyst is a substance that speeds up a chemical
reaction but itself remain unchanged at the end of the
reaction. [Please note that a catalyst can sometimes be
used to slow down the speed of a chemical reaction]
(iii) Shorter time is required for the reaction.
Study hard
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(iv) Copper (II) sulphate speeds up the reaction
between zinc and dilute sulphuric acid.
(c) To maintain a constant temperature of the contents in
the flask.
(d) (i) The volume of gas produced with time.
(ii) Time taken for all the zinc to react completely.
(iii) The temperature of the water bath.
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