F.4/Chemistry/ Suggested Solutions/1st term/12-13/Page 1 of 4
SKH LAM KAU MOW SECONDARY SCHOOL
CHEMISTRY
F.4 FIRST TERM EXAMINATION (2012-2013)
Suggested Solutions
Section A: Multiple Choice Questions (25 marks)
1
2
3
4
5
D
D
C
D
A
6
7
8
9
10
D
D
B
A
A
11
12
13
14
15
C
A
B
B
A
16
17
18
19
20
D
D
D
C
C
21
22
23
24
25
A
C
C
B
D
Section B: Conventional Questions (50 marks)
1. a) 2,8,7
2,8,8,1
1 mark
1 mark
b) i)
1 mark
ii)
1 mark
c) Compound Y has a higher melting point than compound X.
It is because Y is a giant ionic structure, ions are held together by
strong ionic bond while X is a simple molecular structure,
molecules are held together by weak Van der Waals’ forces.
A lot of energy is required to overcome the ionic bond and
little energy is required to overcome Van der Waals’ force.
2. a) Distillation
1 mark
1 mark
(7 marks)
1 mark
b) Condenser/Water condenser
c) 
1 mark
1 mark
The thermometer bulb should be placed at the junction of the adaptor.

The collecting flask should be open.

The direction of water flow should be from the bottom.

A few anti-bumping granules should be added. (any three)
3 marks
(5 marks)
P.1
F.4/Chemistry/ Suggested Solutions/1st term/12-13/Page 2 of 4
3. a) CaCO3
b) i)
Flame test can be performed to show the presence of calcium in coral.
ii)
c) i)
ii)
1 mark
1 mark
A brick red flame is observed.
Bubble the gas into lime water. The gas turns lime water milky.
Ca(OH)2(aq)
/CaCO3(s)
+
+
CO2(g) 
CaCO3(s)
+
H2O(l)

CaCl2(aq)
+
H2O(l)
2HCl(aq)
1 mark
1 mark
1 mark
+
CO2(g)
(5 marks)
4. a) Charcoal / Carbon Powder
1 mark
b)
Marks will be given only if the setup is workable.
2 marks
c) Magnesium oxide
Magnesium oxide is too stable to be reduced / extracted by heating with carbon.
1 mark
1 mark
d) Electrolysis should be employed in the extraction.
1 mark
e) The extraction of copper is carried out a high temperature.
The hot copper metal reacts with oxygen is air and form black copper(II) oxide again.
1 mark
1 mark
(8 marks)
5. a) i)
1 mark
ii)
1 mark
b) i)
XY / NaCl
1 mark
P.2
F.4/Chemistry/ Suggested Solutions/1st term/12-13/Page 3 of 4
ii)
1 mark
iii)
6. a) i)
ii)
Z conducts electricity in aqueous and molten state but not in solid state.
The ions in solid states are not free to move but the ions become mobile
in aqueous and molten state.
1 mark
(6 marks)
Dust, water and carbon dioxide. (any TWO, -½ for each wrong answer)
1 mark
They must be removed as they will solidify and block the passage.
1 mark
b) Air is liquefied by compressing it at a very high pressure and then cooling it.
The compressed air is then expanded quickly in an expansion chamber.
This compressing and expanding cycle is repeated until the air temperature
becomes -200oC or the air is completely liquefied.
c) It is because they have different boiling point. (-½ if melting point is also mentioned)
7. a) i)
1 mark
They both have 7 outermost shell electrons
ii) They have different numbers of occupied electron shells.
b) Carbon, Phosphorus or Sulphur. (any ONE)
c) It is because they have fulfilled the Octet or Duplet Rule,
their electronic arrangements are very stable.
P.3
1 mark
1 mark
1 mark
(5 marks)
1 mark
1 mark
1 mark
1 mark
(4 marks)
F.4/Chemistry/ Suggested Solutions/1st term/12-13/Page 4 of 4
8. a) Physical property:
Lead is a good conductor of heat and electricity but sulphur is not. (or melting point )
1 mark
Chemical property:
Sulphur burns in air when it is heated with a Bunsen flame but lead does not.
1 mark
b) i)
The magnesium strip burns rapidly with a bright flame,
and white ash is formed after the reaction.
1 mark
The copper strip glows slowly in air (copper won’t burn),
and the surface becomes black after the reaction.
1 mark
+ O2(g)

2MgO(s)
2Cu(s) + O2(g)

2CuO(s)
ii) 2Mg(s)
1 mark
(5 marks)
9. a) Hydrogen burns with a 'pop' sound
1 mark
b) Reactivity : Z < Y < X
1 mark
Y is more reactive than Z as Y can displace Cu from CuSO4(aq) but Z cannot.
1 mark
X is more reactive than Y as X can react with cold water but Y cannot
(or, oxide of Y cannot be reduced by carbon but oxide of Y can).
1 mark
c) X is a reactive metal. It reacts with water in the copper(II) sulphate solution and
the colourless gas liberated is hydrogen.
P.4
1 mark
(5 marks)