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SEKOLAH MENENGAH KEBANGSAAN
JALAN ARANG
KUCHING
CHEMISTRY FORM FOUR
PEPERIKSAAN AKHIR TAHUN
2011
MARKING SCHEME
PAPER 1
PAPER 2
PAPER 3
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Answers for Chemistry Paper 1
1 A 2 B 3 A 4 C 5 C
6 B 7 A 8 C 9 C 10 D
11 D 12 A 13 D 14 C 15 C
16 A 17 A 18 D 19 B 20 B
21 A 22 C 23 D 24 C 25 D
26 B 27 A 28 C 29 D 30 B
31 B 32 A 33 B 34 A 35 B
36 A 37 A 38 B 39 C 40 B
41 C 42 A 43 A 44 C 45 D
46 C 47 D 48 C 49 D 50 A
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3
Paper 2 Section A
1 (a) 13 1
(b) 20// 21 1(c) (i) Atoms of the same element which have same proton
number but different number of neutron
1
(ii) B & E 1
(d) (i) correct number of neutron(ii) correct number of proton(iii) correct number of shell and electron
1
11 3
(e) (i) D 1
(ii) A 1
(f) 2.8 1
10
2 (a) The metal oxide burns / glows // droplets of a colourless
liquid formed
1
(b) Anhydrous calcium chlorideto dry the hydrogen gas
11 2
(c)
M O
Mass (g) 92.02 42.34= 49.68
95.86 92.02= 3.84
No. of mol 49.68/ 207 =
0.24
3.84/ 16 =
0.24Simplest
mol ratio
1 1
Empirical formula is MO
1
1
1
1 4
(d) (i) correct reactant(ii) correct product
MO + H2 M + H2O
1
1 2
9
3 (a) (i) Group 1, Period 4 1+1 2
(ii) G 1
(b) (i) D2L 1
(ii) Soluble in water // High melting/ boiling point // Can
conduct electricity in molten or aqueous state
1
(c) (i) E 1
(ii) Nuclei attraction towards valence electrons is weaker in E 1
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4
Thus, it is easier for atom of E to release an electron to
form a positively charged ion 1 2
(d) (i) L / M 1
(ii) Covalent bond 1
10
4 (a) XY3 1
(b) (i) Covalent bond 1
(ii) 2.5 1
(iii) X: Group: 15 , Period : 2
Y: Group : 17 , Period : 2
1
1 2
(c) Low melting and boiling point//cannot conduct
electricity// dissolve in organic solvent
1
(e) (i) correct reactant(ii) correct product(iii) balance equation
X2 + 3Y2 2XY3
1
1
1 3
9
5 (a) P : - , Q : + 1
(b) o allow the ion to flow through 1
(c) - from chemical energy to electrical energy 1
(d) Iron / P is more electropositive than copper / Q // iron is
placed higher than copper in the electrochemical series 1
(e) (i) Intensity of the blue solution decrease 1
(ii) Cu2+
+ 2 e Cu 1
(f) (i) copper electrode / R becomes thicker // a brown solid
deposited
1
(ii) R : - , S : + 1(g) (i) voltage in Figure 5.2 is higher than in Figure 5.1I / more
than 1.2 V
1
(ii) he distance between zinc and copper in the electrochemical
series is further than that between iron and copper
1
10
6 (a) Strong acid is an acid which ionizes completely in water
to produce high concentration of hydrogen ions.
1
1 2
(b) Neutralisation 1
(c) (iv) correct reactant(v) correct product(vi) balance equation
2NaOH + H2SO4 Na2SO4 + 2 H2O
1
1
1 3
(d) Pink to colourless 1
(e) From the equation in (c).
1 mole of H2SO4 reacts with 2 moles of NaOH
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5
1.0x 20.00 = 1MNaOH x 25.00 2
MNaOH = 1.6 moldm-3
1
1 2
(f) 2.0 moldm-3 1
(g) Twice / 50.00 cm3
1
(h) Ammonium sulphate 1
12
Section B
7 (a) (i) Bond which formed when two or more atom share thevalence electron
to achieved the stable electron arrangement
1
1 2
(ii) Ionic bond:
1. Between atom B and C
2. Atom B has electron arrangement 2.8.1
3 .Atom B will donate 1 valence electron4 .to achieve the stable electron arrangement
5 .and become positively charged ion// B B+ + e
6. Atom C has 6 valence electron7. accept 2 electron and become negatively charge ion//
C + 2e
C2-
8. 2 atom B will donate1 electron each to 1 atom C
9 The force of attraction between ions are very strong
Covalent bond:
10. Between atom C and D
11. To achieve the stable electron arrangement12. One atom D will share 4 electron with 2 atom C
13. Force of attraction between molecules are weaker
1
1
11
1
1
11
1
1
11
1 13
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6
(iii)Type of
Compound
Ionic compound Covalent
compound
Melting point &
Boiling point
Higher Lower
Electric
Conductivity
Can conduct
electricity in
molten state oraqueous
solution
Cannot conduct
electricity
Solubility
Dissolve in
water but
cannot inorganic solvent
Dissolve in
organic solvent
but cannot inwater
1
1
1
3
(b) Atom L has 2 valence electron,Donate 2 electron to achive the stable electronarrangement
11 2
20
8 (a) Alkali A sodium hydroxide/ barium hydroxide /
potassium hydroxidestrong alkali
ionises completely in water to produce high concentration
of OH-
Alkali B ammonia solutionWeak alkali
Ionizes partially in water to produce low concentration of
OH-
11
1
11
1 6
(b) (i) X : methylbenzene/ tetrachloromethane/ any organic
solventsY : water
1
1 2
(ii) Hydrogen chloride ionizes completely in waterto form H+, so solution X shows acidic properties .
Without water, hydrogen chloride exists as molecules
There are no H
+
present, so solution Y does not showacidic properties
11
1
1 4
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(c) Calculation2.0x Volume acid = 1.0 x 100
Volume acid = 1.0 x 100 //
2.0= 50 cm3
1. Use a pipette to draw up 50 cm3 2.0 moldm-3sulphuric acid .
2. Transfer the acid to a 100 cm3 volumetric flask.3. Add distilled water to bring the level of solution
until the calibration mark.
4. Stopper the flask and shake well.
1
1
1
1
1
1 6
(d) Add powdered lime/ lime stone / ashes of burnt wood
Reason weak alkali, can neutralize acidity in the soil
1
1 220
Section C
9 (a) Salt is an ionic compound formed when the hydrogen ionin an acid is replaced by a metal ion or an ammonium ion 1
(b) Material
2 mol dm-3
nitric acid, copper (II) oxide powder
Apparatus
250 cm3
beaker, glass rod, filter funnel, retort stand andclamp, Bunsen burner, 250 cm3 conical flask, filter paper,
evaporating dish, 50 cm3 measuring cylinder, spatula.
Procedure
1.
Pour 50 cm
3
of 2 mol dm
-3
nitric acid into a beaker.2. Warm the acid.3. Add copper(II) oxide powder bit by bit into the
acid.
4. Stir the mixture .
1
1
11
1
1
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5. Add copper(IIl) oxide until some of it no longerdissolve.
6. Filter the mixture.7. Heat the filtrate until it become saturated.8. Let it cool9. Filter out the crystals.10.Dry the crystal using the dry filter paper.
Chemical equation:
2 HNO3 + CuO Cu(NO3)2 + H2 O
1
1
1
1
1
1
113
(c) (i) Acid + alkali salt + waterExample:
HCl + NaOHNaCl + H2O
(ii) Acid + metal salt + hydrogenExample :2HNO3 + MgMg(NO3)2 + H2
(iii) Acid + base salt + waterExample:H2SO4 + CuO CuSO4 + H2O
(iv) Acid + metal carbonate salt + water + carbondioxide.Example:
2HCl + CaCO3 CaCl2 + H2O + CO2
1
1
1
1
1
1
1
1
Max
6
20
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10 (a) Solid sodium chloride consists of ions which are held in
fixed positions by strong ionic bonds and are not freely
moving.In aqueous sodium chloride, the ionic bonds are broken
and the ions move freely.
1
1 2
Materials : 0.1 mol dm-3
silver nitate solution, woodensplinter, sandpaper
Apparatus: Batteries, carbon electrodes, silver
lectrodes,
electrolytic cell, connecting wires with crocodile clips,ammeter, test tube and switch.
[ or labelled diagram of set-up of apparatus]
Procedure :
1. An electrolytic cell is half-filled with 0.1 mol dm-3silver nitrate solution.
. The electrodes are connected to batteries and anammeter with connecting wires.
. A test tube filled with silver nitrate solution isinverted over the anode.
. The switch is turned on and electric current is allowedto flow for 15 minutes.
.
Observations at anode and cathode are recorded.. Steps 1- 6 are repeated using silver electrodes in place
of carbon electrodes..Observations:
Observation
Electrode Anode Cathode
Carbon
Bubbles of
colourless gasreleased, relights a
glowing woodensplinter.
A shiny, grey
solid deposited.
Silver
Silver electrode
becomes thinner.
A shiny, grey
solid deposited //cathode becomes
thicker
1
1
1
1
1
1
1
1
1+1
1+1
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ilver nitrate solution consists of Ag +, NO3- , H + ,
H-
ions .
When carbon is made the anode , OH-ions are selectively
ischarged because they are lower than NO3-
ions in the electrochemical series to produce oxygen gas
/
4 OH- O2 + 2 H2O + 4 e
At the cathode, Ag + ions are lower than H + ions in the
lectrochemical series and are selectively discharged toorm silver metal //
Ag + + e Ag
When silver is made the anode, silver atoms ionise to
form Ag
+
ions. The silver anode dissolves //Ag Ag + + e
At the cathode, Ag + ions are lower than H + ions in the
lectrochemical series and are selectively discharged to
orm silver metal //Ag + + e Ag
1
1
1
1
1
17
(ii) Type of electrode// Concentration of electrolyte//
position of ion in Electrochemical Series.
1
20
END OF MARKING SCHEME
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SULIT 4541/32
MARKING SCHEME
CHEMISTRY 3 , 4541/3
Question Rubric Score
1(a)
Able to state all the voltmeter readings accurately with correct unit and
one decimal point.
Sample answer:
Mg and W : 2.0 V
Mg and X : 0.6 V
Mg and Y : 1.4 V
Mg and Z : 2.5 V
3
Able to state all the voltmeter readings accurately without unit.
Sample answer:
Mg and W : 2
Mg and X : 0.60
Mg and Y : 1.4
Mg and Z : 2.5
2
Able to state at least two readings correctly without unit 1
No response or wrong response 0
Question Rubric Score
1(b )
Able to construct a table to record the voltmeter reading for each pair of
metals that contain:
1. Correct titles
2. Readings
Sample answer:
Pairs of metals Voltage / V
Mg and W 2.0
Mg and X 0.6
Mg and Y 1.4
Mg and Z 2.5
3
Able to construct a less accurate table that contains:1. Titles
2. Readings
2
Able to construct a table with at least one title / reading 1
No response or wrong response 0
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SULIT 4541/33
Question Rubric Score
1(c )
Able to give the hypothesis accurately
Sample answer:
The further the distance between two metals in the electrochemical series,
the higher the potential difference / voltage
3
Able to give the hypothesis almost accurately
Sample answer:
The further the distance between two metals, the higher potential
difference/voltage // vice versa
2
Able to state an idea of hypothesis
Sample answer:
Different metals affects the potential difference
1
No response or wrong response 0
Question Rubric Score
1(d )
Able to state all the three variables correctly
Sample answer:
Manipulated variable: Pair of metal
Responding variable: Voltmeter reading/voltage
Constant variable: magnesium/negative electrode, sodium
Chloride solution//electrolyte
r: volume of sodium chloride/electrolyte
3
Able to state any two variables correctly 2
Able to state any one variable correctly 1
No response or wrong response 0
Question Rubric Score
1(e)
Able to arrange in ascending order of all the metals
Sample answer:
Z, W, Y, X, Mg
3
Able to arrange any four metals in correct ascen ding order 2
Able to arrange any three metals in correct ascending order 1No response or wrong response 0
Question Rubric Score
1(f)
Able to predict the value of voltage accurately with unit.
Answer:
1.9 V
3
Able to predict the value of voltage accurately without unit.
Answer:
1.9
2
Able to give an idea the value of voltage.
1.4 < V < 2.5
1
No response or wrong response 0
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SULIT 4541/34
Question Rubric Score
2(a)
Able to state the observation and corresponding infences correctly
Sample answer:
Test tube Observation Inference
A - No reaction
B Bubbles of gas
produced
Hydrogen gas releases
3
Able to state any two answer correctly 2
Able to state any one answer correctly 1
No response given / wrong response 0
Question Rubric Score
2(b)
Able to give the meaning of acid correctlySample answer:
Substance that produced hydrogen gas when reacts with zinc.
3
Able to give the meaning of acid.
Sample answer:
Substance that ionize/dissolve in water to produce hydrogen ion //
substance that produce bubbles when reacts with zinc.
2
Able to give an idea of acid
Sample answer:
Substance that change blue litmus paper to red // substance that has pH
value lower than 7.
1
No response given / wrong response 0
Question Rubric Score
2(c)
Able to explain the role of water correctly
Sample answer:
Water can ionise/dissociate acid to form hydrogen ion.
3
Able to explain the role of water less accurately
Sample answer:
Water can ionise/dissociate acid // water can produce hydrogen ion.
2
Able to give an idea of the role of water.
Sample answer:To show the acidity of acid.
1
No response given / wrong response 0
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SULIT 4541/35
Question Rubric Score
2(d)
Able to write the name of any two products correctly
Sample answer:
1. Zinc ethanoate
2. Carbon dioxide3. water
3
Able to write the name of any one product correctly or any two products
less accurately
Sample answer:
1. zinc ethanoate // carbon dioxide // water
2. CO2 and H2O//(CH3COO)2Zn and CO2//(CH3COO)2Zn and H2O
2
Able to state an idea of the product.
Sample answer:
(CH3COO)2Zn // CO2 // H2O
1
No response given / wrong response 0
Question Rubric Score
2(e)
Able to classify all the acids correctly
Sample answer:
Strong acid Weak acid
Hydrochloric acid. HCl
Nitric acid, HNO3Sulphuric acid, H2SO4
Phosphoric acid, H3PO4Carbonic acid, H2CO3Methanoic acid, HCOOH
3
Able to classify any four acids correctly 2
Able to classify any two acids correctly or give opposite heading
Sample answer:
Weak acid Strong acid
Hydrochloric acid. HCl
Nitric acid, HNO3Sulphuric acid, H2SO4
Phosphoric acid, H3PO4Carbonic acid, H2CO3Methanoic acid, HCOOH
1
No response given / wrong response 0
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Question Rubric Score
3(a)
Able to give the problem statement of the experiment correctly
Sample answer :
Does an acid/glacial ethanoic acid need water to show its acidicproperties? //
Is water needed for an acid/ glacial ethanoic acid to show its acidic
properties?
3
Able to give the problem statement of the experiment incorrectly
Sample answer :
To investigate/study the role of water in showing the properties of
an acid.
2
Able to state an idea of problem statement of the experiment
Sample answer :
Water is needed to show the properties of acid. 1No response or wrong response 0
Question Rubric Score
3(b)
Able to state All variables correctly
Sample answer :
Manipulated variable : Presence of water
Responding variable : Acidic properties // Gas produced
Constant variable : Acid // glacial ethanoic acid // magnesiumr : Volume of acid
3
Able to state any two variables correctly 2
Able to state any one variables correctly 1
No response or wrong response 0
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SULIT 16 4541
Question Rubric Score
3(d)
Able to give the list of the apparatus and materials correctly
and completely
Sample answer :
Apparatus : dry test tube
Material : Glacial ethanoic acid, water, magnesium ribbon,
wooden splinter
3
Able to give the list of the apparatus and materials correctly
but not completely
Sample answer :
Dry test tube
Glacial ethanoic acid, water, magnesium ribbon
2
Able to give an idea about the list of the apparatus and
substances correctly
Sample answer :
Test tube and any one substance
1
No response or wrong response 0
Question Rubric Score
3(c)
Able to give the hypothesis correctly
Sample answer :
Water is needed for an acid to show its acidic properties //
Presence of water is essential for an acid to show its acidicproperties.
3
Able to give the hypothesis almost correct
Sample answer :
Ethanoic acid/An acid shows its acidic properties when water is
present //The presence of water influence the acidic properties
of acid
2
Able to state an idea of the hypothesis
Sample answer :
The water affect the properties of acid
1
No response or wrong response 0
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SULIT 17 4541
Question Rubric Score
3(e)
Able to state all procedures correctly
Sample answer :
1. Glacial ethanoic acid is poured into two different dry testtube labeled A and B.
2. Distilled water is added into glacial ethanoic acid in testtube B.
3. A piece of magnesium ribbon is put into test tube A and B.4. A lighted wooden splinter is placed at the mouth of both test
tubes.
5. The observation is recorded.
3
Able to list down steps 1, 2 and 3 2
Able to list down steps 1 and 3 or 2 and 3 1
No response or wrong response 0
Question Rubric Score
3(f)
Able to exhibit the tabulation of data that includes the following
two information correctly
1. Heading for the manipulated variable2. Heading for the responding variable
Sample answer :
(Test tube) //
(Condition of acid)
Observation
Test tube A //Glacial
ethanoic acid
Test tube B
//Ethanoic acidsolution /in water
2
Able to exhibit the tabulation of data less accurately
Tabulation of data has the following elements :
1. Heading for the manipulated variable2.
Heading for the responding variable3. One condition of acid listed
Sample answer :
Acid/test tube Effect//Result
Glacial ethanoic acid
1
No response or wrong response 0
END OF MARKING SCHEME