Kimia P1 Sbp Mid Year Spm 2008

SULIT SULIT 4541/1 Kimia Kertas 1 Mei 2008 1¼ jam

4541/1

BAHAGIAN SEKOLAH KEMENTERIAN PELAJARAN MALAYSIA ______________________________________________ PEPERIKSAAN PERTENGAHAN TAHUN 2008 TINGKATAN 5

KIMIA Kertas 1 Satu jam lima belas minit

JANGAN BUKA KERTAS SOALAN INI HINGGA DIBERITAHU 1. 2. 3. 4. 5. 6. 7.

Kertas soalan ini mengandungi 50 soalan. Jawab semua soalan Jawab dengan menghitamkan ruangan yang betul pada kertas jawapan Bagi setiap soalan hitamkan satu ruangan sahaja Sekiranya anda hendak menukar jawapan, padamkan tanda yang telah dibuat. Kemudian hitamkan jawapan yang baru. Rajah yang mengiringi soalan tidak dilukiskan mengikut skala. Anda dibenarkan menggunakan kalkulator saintifik yang tidak boleh diprogramkan.

Kertas soalan ini mengandungi 23 halaman bercetak

SULIT

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SULIT INFORMATION FOR CANDIDATES 1

This question paper consists of 50 questions.

2

Answer all questions.

3

Answer each question by blackening the correct space on the answer sheet.

4

Blacken only one space for each question.

5

If you wish to change your answer, erase the blackened mark that you have made. Then blacken the space for the new answer.

6

The diagrams in the questions provided are not drawn to scale unless stated.

7

You may use a non-programmable scientific calculator.

SULIT

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SULIT 1

After making observations, a chemist should try to A B C D

2

collect data make inference make hypothesis identify problems

The diagram shows a model of an atom. Electron Shell Nucleus that contains proton and neutrons

Who introduced this model? A B C D

3

What is the relative molecular mass of hydrated magnesium sulphate, MgSO4.7H2O? [Relative atomic mass: Mg, 24; S,32; O,16; H,1] A B C D

SULIT

Neils Bohr J.J Thomson James Chadwick Ernest Rutherford

145 246 305 356

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SULIT 4

The table shows the properties of element Q. Element Q

Properties   

Non-flammable Used as carrier gas in gas-liquid chromatography Filled in electric light bulbs

Which of the following elements is Q? A B C D

5

Sodium Helium Argon Silver

The table shows the electron arrangement for elements M, N, P and Q. Element M N P Q

Electron arrangement 2.4 2.8.2 2.6 2.8.7

Which of the following elements react to form an ionic compound? A B C D

6

M and P P and Q M and Q P and N

The diagram shows the electrolysis of molten lead(II) bromide using carbon electrodes.

Carbon Lead(II) bromide

heat What are the products at the anode and the cathode?

A B C D SULIT

Anode Bromine Oxygen Bromine Oxygen

Cathode Lead Hydrogen Hydrogen Lead 4

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SULIT 7

Which of the following is a weak alkali? A B C D

8

Which of the following salts is prepared through precipitation process? A B C D

9

Lithium hydroxide Aqueous ammonia Cooper(II) hydroxide Potassium hydroxide

Lead(II) chromate(VI) Ammonium chloride Potassium carbonate Barium chloride

The diagram shows the formation of ammonia through Haber process. Nitrogen

Hydrogen

Catalyst X Temperature Y Pressure Z

Ammonia Which of the following represent catalyst X, temperature Y and pressure Z?

A B C D

10

Temperature Y, oC 550 450 200 450

Pressure Z / atm 200 100 450 200

Which of the following is the meaning of activation energy? A B C D

SULIT

Catalyst X Vanadium(V) oxide Platinum Iron Iron

The maximum energy that the particles need to produce effective collision The amount of energy used by the particles during a collision The amount of kinetic energy of molecules during a collision The minimum amount of energy that particles must have in order to react

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SULIT 11

Which of the following structural formulae shows an unsaturated hydrocarbon?

A

B

C

D

12

The diagram shows the atomic symbol of element X. 7

X 3 Which of the following is true about the sub-atomic particles of element X?

A B C D

SULIT

Proton Number 7 7 3 3

Number of neutron 7 7 4 4

6

Number of electron 10 7 3 2

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SULIT 13

What is the number of oxygen atom in 0.1 mole of water? [Avogadro constant: 6.02 x 1023 mol-1] A B C D

14

6.02 x 1022 6.02 x 1023 60.2 x 1023 3.01 x 1023

X is an element that has the following properties;  Soft solid  Reacts with cold water to form alkaline solution  Store in paraffin oil Among elements A, B, C and D in the Periodic Table of elements, which element represent X?

15

The diagram shows the electron arrangement of a compound formed between atoms P and Q. 2+

P

2-

Q

Which of the following statements is true about the compound? A B C D

SULIT

There is strong intermolecular force between particles P and Q The compound is formed by sharing the electrons The compound conduct electricity in molten state It is an covalent compound

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SULIT 16

The diagram shows the set-up of the apparatus used to electrolyses 0.1 mol dm-3 of copper(II) chloride solution by using carbon electrodes.

Carbon Copper(II) chloride solution What is observed at the anode? A B C D

17

18

Which of the following equations shows the neutralization process? I II III IV

CuO + H2SO4  CuSO4 + H2O Zn + 2HCl  ZnCl2 + H2 NH3 + HNO3  NH4NO3 CaCO3 + H2SO4  CaSO4 + H2O + CO2

A B C D

I only II and IV only I and III only I, II and IV only

Which of the following ions form a white precipitate that does not dissolves in excess sodium hydroxide solution but no change occur in aqueous ammonia solution? A B C D

SULIT

Colourless gas bubbles released Greenish yellow gas evolved Brown solution produced Brown solid deposited

Mg2+ Pb2+ Ca2+ Al3+

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SULIT 19

The diagram shows the lead crystal glass.

What are the major components used in the making of lead crystal glass? A B C D

20

Copper(II) oxide and lead(II) oxide Aluminium silicate and silicon dioxide Silicon dioxide and lead(II) oxide Iron(III) oxide and boron oxide

Chemical equation shows the reaction between zinc and sulphuric acid.

H2SO4(aq) + Zn(s) 

ZnSO4(aq) + H2(g)

Which of the following factors increases the rate of reaction? A B C D

21

Increases of volume of sulphuric acid Use of lower concentration of sulphuric acid Addition of small amount of copper(II) sulphate Use bigger size of zinc

The diagram shows the cooking gas cylinder.

Which of the following gasses is filled in the gas cylinder? A B C D

SULIT

Methane Ethene Propene Butane

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SULIT 22

The graph shows the cooling curve of acetamide. Temperature/ oC S

T

U V Time/ s

Which of the following statements are true about the particles in acetamide from S to V?

23

I II III IV

Heat energy is released by particles The kinetic energy of the particles increase The particle are closer to one another The movement of the particles becomes slower

A B C D

I and III only III and IV only II, III and IV only I, III and IV only

The chemical equation shows the burning process of ethene in excess air.

C2H4(g) + 3O2  2CO2(g) + 2H2O(l) What is the maximum volume of carbon dioxide gas evolved when 0.5 mole of ethene burns completely? [1 mole of gas occupied 24 dm3 at room temperature and pressure] A B C D

SULIT

12 dm3 24 dm3 36 dm3 48 dm3

10

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SULIT 24

The diagram shows the structure of atoms Q and R.

Atom Q

Atom R

Which of the following is true about atoms Q and R? A B C D

25

The electron arrangement of atom J is 2.6 and atom G has 4 valence electrons. What type of bond and the chemical formula of the compound formed between atoms J and G?

A B C D

26

Q exists as a diatomic molecule Q and R have the same chemical properties R reacts with Q to form an ionic compound Q reacts with water to release hydrogen

Type of bond Ion Ion Covalent Covalent

Chemical formula JG2 GJ2 GJ2 JG2

The diagram shows the set-up of apparatus for the electrolysis of silver nitrate solution.

Silver

Silver Silver nitrate solution

What is formed at the cathode? A B C D

SULIT

Silver atoms Oxygen gas Hydrogen gas Silver ions

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SULIT 27

The distilled water is added to 20 cm3 of 1.0 mol dm-3 sodium hydroxide solution to produce 250 cm3 of sodium hydroxide solution. What is the concentration of the sodium hydroxide solution produced? A B C D

28

Ammonium sulphate is used as a chemical fertilizer. This fertilizer can be prepared in the laboratory through the reaction between A B C D

29

0.02 mol dm-3 0.04 mol dm-3 0.06 mol dm-3 0.08 mol dm-3

aqueous of ammonia solution and dilute sulphuric acid aqueous of ammonia solution and sulphur dioxide ammonia gas and sulphur and oxygen ammonia gas and sulphur trioxide

The diagram shows the arrangement of atoms in steel. Iron atom X atom

What is X? A B C D

SULIT

Tin Zinc Carbon Copper

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SULIT 30

The graph shows the maximum volume of carbon dioxide gas evolved when calcium carbonate react with hydrochloric acid. Volume of CO2 gas/ cm3

35

Time/ s 120 What is the rate of reaction at 120 s? A B C D

0.00 cm3 s-1 0.15 cm3 s-1 0.29 cm3 s-1 0.35 cm3 s-1

31 Compound X

Steam/Catalyst

Compound Y

Process A

Acidified potassium dichromate (VI)

CH3COOH

What could be the organic compounds X and Y, Catalyst and Process A in the diagram? Compound X A B C D

SULIT

Ethene Ethane Ethane Ethene

Compound Y Ethanol Ethene Ethene Ethanol

13

Catalyst Phosphoric acid Nickel Nickel Phosphoric acid

Process A Oxidation Hydrogenation Oxidation Hydrogenation

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SULIT 32

The table shows the melting point and boiling point for substances P, Q, R and S. Melting point/ oC 79 -180 -95 -160

Substance P Q R S

Boiling point/ oC 108 -120 69 -90

Which of the substances exists as a liquid at room temperature? Q A R B S C P D

33

The equation shows the reaction of the extraction of iron from iron(III) oxide. 2Fe2O3



4Fe + 3O2

What is the mass of iron which can be extracted from 10.0 g of iron(III) oxide? [Relative atomic mass: Fe,56; O,16] A B C D

34

3.5 g 4.5 g 6.0 g 7.0 g

The table shows the proton number for element M and N. Element N is more electronegative than element M because Element M N A B C D

SULIT

Proton number 8 9

atomic size of N is smaller atom N releases electrons easier atom N has less valence electron atom N has larger number of neutron

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SULIT 35

The diagram shows the information of elements X and Y 7

16

X

Y

3

8

Which of the following is the diagram of electron arrangement for the compound formed when element X reacts with element Y?

A

B

C

D

SULIT

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SULIT 36

The diagram shows the voltaic cell.

Copper

Magnesium

Copper(II) chloride solution

Magnesium nitrate solution

Which of the following half-equations represent the reaction at the negative terminal and positive terminal?

37

Negative Terminal

Positive terminal

A

Mg  Mg2+ + 2e

Cu2+ + 2e 

B

Mg2+ + 2e  Mg

Cu  Cu2+ + 2e

C

Cu2+ + 2e 

Mg  Mg2+ + 2e

D

Cu  Cu2+ + 2e

Mg2+ + 2e  Mg

Which of the following solutions has the highest concentration of hydrogen ion? A B C D

38

Cu

Cu

50 cm3 of 1.0 mol dm-3 H2SO4 solution 50 cm3 of 2.0 mol dm-3 H2SO4 solution 100 cm3 of 1.0 mol dm-3 H2SO4 solution 150 cm3 of 1.0 mol dm-3 H2SO4 solution

The reaction between lead(II) nitrate and potassium iodide solution is represented by the equation below Pb(NO3)2 (aq) + 2KI (aq)  PbI2 (s) + 2KNO3 (aq) 10.0 cm3 of 1.0 mol dm-3 potassium iodide solution is mixed with 20.0 cm3 of 1.0 mol dm-3 lead(II) nitrate solution. What is the maximum mass of lead(II) iodide produced in this reaction? [Relative atomic mass: I ,127 and Pb, 207]

SULIT

A

3.34 g

B

4.61 g

C

6.68 g

D

9.22 g

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SULIT 39

The diagram shows a structural formula of a polymer. H

H

C

C

H

Cl

n

Which of the following is the monomer of the polymer?

A Cl

Cl

B

Cl

C

D

SULIT

Cl

Cl

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SULIT 40

The graph shows the volume of carbon dioxide gas released against time for the reaction between 25 cm3 of hydrochloric acid with excess marble. CaCO3 + 2HCl  CaCl2 + CO2 + H2O

Volume of CO2/ cm3

180

Time/s What is the concentration of acid used? [Molar volume: 24 dm3 mol-1 at room temperature] A B C D

41

0.3 mol dm-3 0.4 mol dm-3 0.5 mol dm-3 0.6 mol dm-3

 

3.0 g of carbon reacts with 0.5 g of hydrogen gas to form compound X. Relative molecular mass of compound X is 42.

What is the molecular formula of compound X? [Relative atomic mass: C,12; H,1] A B C D

SULIT

CH2 C2H4 C2H6 C3H6

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SULIT 42

Magnesium ribbon reacts with element Q from group 17 in Periodic Table. Which of the following chemical equations is correct? A B C D

43

44

SULIT

Mg + Q Mg + Q2 2Mg + Q2 Mg + 2Q

→ → → →

MgQ MgQ2 2MgQ MgQ2

Which of the following pairs show the correct uses of the isotopes?

I II III IV

Isotope Cobalt-60 Carbon-14 Iodine-131 Sodium-24

A B C D

I and II only II and IV only I,II and III only I, II, III and IV

Uses To destroy bacteria in food To estimate the age of artifacts To detect the location of tumour To detect leaks in underground petroleum piping

Sulphur dioxide gas, SO2 causes environmental pollution. Which of the following environmental pollutions is affected by sulphur dioxide, SO2? I II III IV

pH of the soil increases Lakes and rivers become acidic Salts are leached out of the top soil Buildings and metal structures will corrode

A B C D

I and II only I and III only II, III and IV only I, II, III and IV

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SULIT 45

Which of the following diagrams is used to electroplate an iron spoon with silver?

A

Silver strip

Iron spoon

Silver chloride

B

Silver strip

Iron spoon

Silver nitrate

C Silver strip

Iron spoon

Silver chloride

D

Iron spoon

Silver strip Silver nitrate

SULIT

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SULIT 46

What is the volume of 0.2 mol dm-3sulphuric acid solution required to completely neutralize 50 cm3 of 0.2 mol dm-3 potassium hydroxide solution? 25 cm3 30 cm3 45 cm3 50 cm3

A B C D

47

The diagram shows the structural formula of compound X.

Compound X Which of the following is an isomer of X? A

B

C

D

SULIT

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SULIT 48

49

SULIT

Which pair of the organic compounds below can be distinguished by using acidified potassium manganate(VII)? A

C2H6 and C3H8

B

C2H5OH and C3H6

C

CH3CH2COOH and CH3CHCHOH

D

CH3CH2CH2CH3 and CH2CHCH2CH2CH3

Which of the following reactions represent the precipitation reactions? I II III IV

Pb(NO3)2 Ba(NO3)2 Pb(NO3)2 Ca(NO3)2

+ + + +

Na2SO4 2KCl 2KCl Na2SO4

A B C D

I and III only I, II and III only I, III and IV only 1, II, III and IV

→ → → →

22

PbSO4 + 2NaNO3 BaCl2 + 2KNO3 PbCl2 + 2KNO3 CaSO4 + 2NaNO3

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SULIT 50

The diagram shows the graph of volume of oxygen gas against time. Curve I is obtained from the decomposition of 20 cm3 of 0.2 mol dm-3 hydrogen peroxide solution. Volume of oxygen /cm3

2V

II

V

I

Time/s Which of the following solutions will produce curve II? A B C D

40 cm3 0.1 mol dm-3 hydrogen peroxide solution 20 cm3 0.4 mol dm-3 hydrogen peroxide solution 30 cm3 0.2 mol dm-3 hydrogen peroxide solution 40 cm3 0.4 mol dm-3 hydrogen peroxide solution

END OF QUESTION PAPER

SULIT

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SULIT 4541 Chemistry Marking Scheme Mei 2008

4541/1/2/3

BAHAGIAN SEKOLAH KEMENTERIAN PELAJARAN MALAYSIA ______________________________________________ PEPERIKSAAN PERTENGAHAN TAHUN 2008

FORM 5 CHEMISTRY MARKING SCHEME FOR PAPER 1, 2 AND PAPER 3

Peraturan pemarkahan ini mengandungi halaman bercetak.

1

PAPER 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

B C B C D A B A D D D C A A C B C C C C

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

2

D D B A C A D A C A A B D A C A D B B D

41 42 43 44 45 46 47 48 49 50

D B D C B A B D C B

PAPER 2-SECTION A No. 1

Rubric a

Mark

G

1

Has stable /octet electron arrangement//8 valence electron

1

2A + 2H2O  2AOH + H2

1

Use a small pieces//use a forcep// use a google

1

c

G,E,D, A,J,L

1

d

Has same valence electron// valence electron is 1

1

e (i)

DE2 r: E2D

1

b (i) (ii)

(ii)

[can draw the diagram of electron arrangement correctly] - Correct structure of atoms - Correct ratio of atoms=1:2

2

Has (neutral ) molecule

1

TOTAL

10

a

T1

1

b(i)

PQ: solid + liquid

1

RS: liquid

1

Heat energy absorbed

1

is used to overcome the forces of attraction between particles

1

(iii)

2

(ii) c

// Heat is absorbed to overcome the intermolecular forces r: ion/atom (1+1) d

The particles / molecules move faster

1

e (i)

Iodine/I2//napthalene/C10H8

1

(ii)

Copper/ Cu

1

(iii)

Ion

1

Diffusion

1

TOTAL

10

3

3

a (i)

3H2 + N2  2NH3

1

(ii)

( Extract from ) air

1

Neutralization

1

H2SO4+ 2NH3  (NH4)2SO4

1

b (i) (ii)

//H2SO4+ 2NH4OH  (NH4)2SO4 + H2O (iii) c (i)

Fertilizer

1

Tin

1

(ii)

Copper atom

Tin atom

Copper atom

(1+1) 

d

In pure copper the layer of atom are easily slide over each other when external force is applied on them.



1

The different size of foreign atoms in allloy are prevent the layers of atom from slide each other when external force is

1

applied.

4

a

TOTAL

10

1 Diagram of set up of apparatus complete and functional

1

2 Label (Anode) – impure copper and (cathode )– pure copper

1

3 ( Electrolyte) – copper (II) sulphate / copper (II) chloride // copper (II) nitrate solution

1

a: chemical formula

b(i)

(ii)

1 become thinner // decrease in mass

1

2 become thicker // increase in mass

1

1 ( Remain )unchanged

1

2 Number of Cu2+ ions produced at anode same as number of copper atoms produced at cathode // the rate of formation of Cu2+

4

ions at the anode is the same as the rate of discharge of Cu2+ at cathode.

c (i) (ii)

d

5

1

(Anode ):Cu  Cu2+ + 2e (Cathode ): Cu

2+

1

+ 2e  Cu

1

Electroplating of metals/ Extraction of reactive metals

1

TOTAL

10 

a

2H2O2

b

Number of mole of H2O2 = 20 x 2/1000= 0.04

O2 + 2H2O

1

1

2 mol of H2O2 produce 1 mol of O2 // Number of mole of O2 = 0.04/2 = 0.02

1

Volume, O2 = 0.2 x 24dm3 = 4.8 dm3 c (i) (ii)

1

Rate of reaction in experiment II is higher than experiment I 

The concentration/number of molecule per unit volumeof hydrogen peroxide in II is higher

d

1 1 1



The frequency of collision between H2O2 molecule is higher



The frequency of effective collision is higher

1

Volume of gas/cm3

II I

Time(s) Label Y axes and X axes Correct curve and label I and II

1 1

10

TOTAL

5

6

A compound that contain element of carbon and derive from living

a

1

organisms.

C2H4

1

(ii)

ethene

1

(iii)

double bond between carbon atoms

1

b (i)

(a: C=C ) c (i)

Acidified potassium manganat (VII) // Acidified potassium

1

dicromate (VI) (ii)

Oxidation

1

(iii)

Purple to colourless // orange to green

1

C2H4 + H2O  C2H5OH

1

(ii)

Alcohol

1

(iii)

Temperature 300 oC // Pressure 60 atmosphere // concentrated

d (i)

phosphoric acid

1

TOTAL

10

6

SECTION B No. 7

Rubric a (i)

Mark

Compound that form when non metal atom gain/receive/accept electron that release/lose/donate by metal atom to achieve stable /octet/duplet electron arrangemen

1

(ii) Compound that form between non metal atom by sharing their valence electron to achieve stable/octet /duplet electron

1

arrangement

b

Between P and Q  

Atom X has 1 valence electron

1 +

Atom X loses/donates/transfers 1 electrons to form X ion //

X X+ + e- and attain stable octet electron arrangement 

Atom Y has 7 valence electrons



Atom gains/receives/accept 1 electron to formY- ion//

1 1 1

Y + e-Y

attain the stable /octet electron arrangement



The two oppositely-charged ions// the X+

1

and Y- ion are

bonded together by a strong electrostatic force 

To form a ionic compound with the formula XY// diagramn

X Y

Max 7

7

1 1

(ii)

Between Y and Z 

Atom Z has 4 valence electrons and atom Y has 1 valence

1

electrons 

One atom Z contributes 4 electrons and (each) atom Y 1

contributes one electron for sharing . 

Atom Z shared 4 pairs of electron with 4 atoms Y



to attain a octet /stable electron arrangement respectively



diagram

1 1 1

Y

Z

Y

Y

Y

(iii) 

Magnesium oxide is an ionic compounds



Strong electrostatic force of attraction exists between

1

1

Mg2+ and O2 -// the oppositely-charged magnesium ions and oxide ions in Magnesium oxide are held together by strong ionic bonds 

A lot of heat energy // high of energy is required to break the strong forces

1



Tetrachloromethane is a covalent compound

1



Weak intermolecular forces //held together by weak (Van der

1

Waals) force of attractions between molecule 

little heat energy //low energy is needed to overcome the weak forces

8

1

8

a

TOTAL 20 Empirical formula- Formula shows simplest ratio of atoms of each 1 element in the compound Molecular formula- Formula shows actual number of atoms of each element in the compound

b

Molecular Formula = ( Empirical formula )n = ( CH2 )n Relative Molecular Mass ( CH2 )n = 70 12n + 2n= 70 14n=70 n=5 Molecular Formula C5H10

c(i)

1

1

1 1

1. Metal Z is cleaned using sand paper

1 2. A crucible and its lid are weighed and the mass is recoded 1 3. Metal Z is palced in the crucible. The crucible,lid and its content is weighed and the mass is recorded.

1

4. The crucible with its content is heated strongly without lid.

1

5. When metal Z start burn, the crucible is covered by its lid

1

6. the covered is raise a little at intervals

1

7. When there is no more reaction, the lid is removed and the crucible is heated strongly for a few minutes. 8. Cool the crucible and weigh the crucible,its lid and its

1 1

Content and record the mass. 9. The process of heating, cooling and weighing is repeated

1

until constant is obtained. 10. (Precaution step ); Close the crucible immediately to prevent loss of

9

1

Element

Z

O

Mass(g)

1.30

0.32

1

1 mol

1.30/65=0.02

0.32/16=0.02 1

Simplest ratio

1

1 1

Empirical Formula ZO

1

TOTAL

20

10

PAPER2 –SECTION C Rubric

No 9

Mark

Sample answer :

a

Zn + HNO3 

Zn(NO3)2 + H2O

ZnCO3 + HNO3  Zn(NO3)2 + H2O + CO2 ZnO + HNO3  Zn(NO3)2 + H2O

b (i)

(ii)

c(i)

Any two

2



Methanoic acid partial ionizes in water

1



produce low concentration of hydrogen ion

1



Glacial ethanoic acid has (neutral) molecule

1



Methanoic acid aqueous ionizes in water

1



to produce free moving ion

1

Procedure : 1 100 cm3 of 0.1 moldm-3 sulphuric acid is poured into a beaker

1

and heated slowly. 2 zinc carbonate is added into the sulphuric acid until in excess/no longer dissolves.

1

3 Stir the solution and filtered.

1

4 The filtrate is poured into an evaporating dish and heat until saturated

1

5 The hot saturated salt solution is allowed to cool 1 6 The crystals formed are filtered out, rinsed with distilled water 7 dried between sheets of filter paper.

11

1

(ii)

ZnCO3 + H2SO4  ZnSO4 + H2O + CO2

1

Number of mole , H2SO4 = 0.1( 100 )/1000 = 0.01

1

1 mol of H2SO4 produce 1 mol of ZnSO4 1

Mole of ZnSO4 = 0.01 Mass of ZnSO4 = 0.01 X 161 = 16.1 g Sample answer :

d

1 ammonium chloride as a fertilizer 2 copper (II) sulphate as a pesticide 3 hydrated calcium sulphate to make plaster casts 4 sodium chloride food additive Any 2 suitable anwers(1+1) TOTAL 10a

1

(i) (ii) (iii)

1 1

20

catalyst

1

esterification

1

CH3COOH + C3H7OH  CH3COOC3H7 + H2O

1

Correct reactant Correct product

1

(iv)

Ethyl propanoate Sweet smell/fruity smell/fragrant smell //insoluble in water/soluble in organic solvent //colourless //less dense than water

2

any two properties (1+1) (v)

2

12

 b

(i)

Bacteria will produce lactic acid/H+ ions which neutralize negatives charge of the protein membrane/ rubber molecules



The rubber molecules will be collide with each other and cause protein membrane broken



1 1

Rubber polymer are released and lump together 1



Hydroxide ions/OH- from ammonia solution will neutralise H+ produced by acid



The protein membrane remains negatively charged



The rubber particles repel each others/ the rubber polymers cannot combine and coagulate

(ii)



1 1

The presence of cross-linkage of sulphur atoms between the rubber molecule



1

1

When vulcanized rubber is stretched and release, the crosslinkage will pull the chain back to their original arrangement

1



Diagram



Improves the elasticity and strength of the rubber / make

1

vulcanized rubbers more resistant to heat /organic solvent 1

 or Resistant to oxidation : 

The presence of cross-linkage of sulphur atoms between the rubber molecule

1



Diagram



C=C in vulcanized rubber is less than C=C in the

1

unvulcanized rubber, 

1

so vulcanize rubber is more resistant to oxidation 1 TOTAL 20

13

PAPER 3 1 (a) KK0503 – Measuring and using numbers EXPLANATION [Able to write all the times with units accurately] Suggested answer:

SCORE 3

t1 55.0 s, t2 48.0 s , t3 42.0 s , t4 37.0 s , t5 33.0 s [Able to record all the times accurately but without units / no decimal place] t1 55.0 , t2 48.0 , t3 42.0 , t4 37.0 , t5 33.0 // // t1 55 s , t2 48.0 s , t3 42 s, t4 37s, t5 33s

2

[Able to write at least 3 readings of the times accurately]

1

No response given / wrong response

0

1 (b) KK0501- Observation EXPLANATION [Able to state the colour of sulphur and the rate of it is formed] Suggested answer:

SCORE 3

Pale / light yellow precipitate is slowly formed [Able to state the colour of sulphur] Pale / light yellow precipitate is formed. [Able to state the formation of precipitate] A precipitate is formed. No response given / wrong response

2 1 0

1 (c) KK0506 – Communicating EXPLANATION [Able to construct a table correctly containing three labeled columns with correct units and record all the time and 1/time accurately ]

SCORE

Suggested answer: Temperature, o C Time , s 1 / time , s-1

30

35

40

45

50

55.0 0.018

48.0 0.021

42.0 0.024

37.0 0.027

33.0 0.030

3

[Able to construct a table correctly containing three labeled columns with correct units and record all the time and 1/time but not accurately]

2

[Able to write at least 3 readings of the times accurately]

1

No response given / wrong response

0

1 (d) (i) KK0506 Communicating 14

EXPLANATION [Able to draw a graph accurately that consists of the following aspects] Suggested answer:

SCORE 3

1. Both axes labeled and units ( Y axis - temperature , X axis – 1/ time ) 2. All points transferred correctly 3. Uniform scale, graph size covers at least half of the graph paper. 4. Straight line/ best fits drawn [Able to draw a graph that consists of the following aspects] 1. Both axes labeled / units ( Y axis - temperature , X axis – 1/ time ) 2. At least three points transferred correctly 3. Uniform scale, graph size covers at least half of the graph paper. 4. Straight line/ best fits drawn

2

[Able to draw a graph that consists of the following aspects] 1. Both axes labeled and units ( Y axis - temperature , X axis – 1/ time ) 2. Draw a line

1

No response given / wrong response

0

1(d)(ii) KK0509 – To define Operationally EXPLANATION [Able to interpret the relationship between the rate of reaction and the temperature of sodium thiosulphate solution from graph accurately] Suggested answer: The rate of reaction is directly proportional to the temperature of sodium thiosulphate solution // As the temperature of sodium thiosulphate increases the rate of reaction increases. [Able to interpret the relationship between the rate of reaction and the temperature of sodium thiosulphate solution from graph ] The rate of reaction is proportional to the temperature // the temperature is proportional to the rate of reaction // the rate of reaction increases when the temperature increases. [Able to state an idea of hypothesis The temperature affects the rate of reaction. No response given / wrong response

SCORE 3

2

1

0

15

Temperature /oC

50

X

45

X

40

X

35

X

30 X 0.015

0.020

0.025

16

0.030

1/time , s-1

1(e) KK0510 - State variables EXPLANATION [Able to state three variables and three action to be taken] Suggested answer: Variable Manipulated: Temperature

Action to be taken Heat the sodium thiosulphate solution at different temperature // Use different temperature. Record the time taken for “X” mark to disappear from view.

SCORE

3

Responding: Rate of reaction / time taken for “X” marks to disappear from view. Controlled : Use the same concentration and Concentration and volume of H2SO4, volume of H2SO4 /sodium concentration and volume of sodium thiosulphate solution // Use same thiosulphate solution, size of conical size conical flask. flask. [Able to state any two variables and any two action to be taken]

2

[Able to state any one variables and any one action to be taken]

1

No response given / wrong response

0

2 (a) KK0506 Communicating EXPLAINATION [Able to write the correct overall ionic equation] Suggested answer: Mg + Cu2+  Mg2+ + Cu Mg + CuSO4  MgSO4 + Cu Mg  Mg2+ + 2e // Cu2+ + 2e  Cu No response given / wrong response

SCORE 3

2 1 0

2(a)(i) KK 0504 – Making inference EXPLANATION [Able to state the correct inference] Suggested answer: Magnesium atom releases/donate/loses electrons to produce magnesium ion // Magnesium is corrode. Magnesium becomes thinner // mass of magnesium decreases Magnesium dissolves No response given / wrong response

17

SCORE 3

2 1 0

2(b) KK 0505 - Predicting EXPLANATION [Able to state the voltage value] 0.65 V 0.63 – 0.64 V // 0.66 – 0.67 V < 0.64 V // > 0.67 V No response given / wrong response 2(c)KK 0508 – Interpreting Data EXPLANATION [Able to arrange the position of all metals in an ascending order based on tendency to release electrons correctly] Copper > Lead > Iron > Zinc > Magnesium

SCORE 3 2 1 0

SCORE 3

[Able to arrange the position of all metals in descending order based on tendency to release electrons] Magnesium > Zinc > Iron > Lead > copper

2

[Able to arrange the position of at least four metals in ascending order based on tendency to release electrons correctly]

1

No response given / wrong response

0

2(d) KK0509 – Operational definition EXPLANATION [Able to state the correct and complete operational definition] Suggested answer:

SCORE 3

The further the metal is from copper in the electrochemical series, the greater is their voltage reading. // [Able to give incomplete relationship] Suggested answer:

2

The further apart the metal is in the electrochemical series, the greater the potential difference / voltage reading. [Able to state an idea] Suggested answer:

1

The position of metal influence the voltage reading // Type of metal influence the voltage reading. No response given / wrong response

0

18

3.(a) KK051021 – Statement of problem EXPLANATION [Able to make a suitable statement of problem] Suggested answer: How to differentiate between magnesium nitrate solution and calcium nitrate solution // How to differentiate between magnesium ion and calcium ion [Able to make a suitable aim] Suggested answer:

SCORE 3

2

To differentiate the presence of magnesium ion and calcium ion by using aqueous ammonia solution. [Able to state an idea of statement of problem or aim]

1

No response given / wrong response

0

3(b) KK051202 – Stating hypothesis EXPLANATION [Able to state the relationship between manipulated variable and responding variable correctly] Suggested answer: If the addition of aqueous ammonia solution forms white precipitate which is insoluble in excess ammonia aqueous solution, then the solution tested is magnesium nitrate. // If aqueous ammonia solution is added and no change occur then the solution tested is calcium nitrate. [Able to state the relationship between manipulated variable and responding variable] [Able to state an idea of the hypothesis] No response given / wrong response

SCORE 3

2 1 0

3 (c) KK051202 – Stating variables EXPLANATION [Able to state all the three variables correctly] Suggested answer: Manipulated variable : magnesium nitrate and calcium nitrate // Mg2+ and Ca2+ Responding variable: formation of white precipitate Controlled variable : aqueous ammonia solution [Able to state any two of the variables correctly] [Able to state one of the variables correctly or state idea regarding variable] No response given / wrong response

19

SCORE

3(d) KK051205 – List of substances and apparatus EXPLANATION [Able to state the list of substances and apparatus correctly and completely] Suggested answer: Test tube, dropper, test tube rack 0.5 mol dm-3 magnesium nitrate solution, 0.5 mol dm-3 calcium nitrate solution, aqueous ammonia solution. [Able to state the list of substances and apparatus correctly but not completely] Suggested answer: Test tube 0.5 mol dm-3 magnesium nitrate solution, 0.5 mol dm-3 calcium nitrate solution, aqueous ammonia solution. [Able to state an idea about the list of substances and apparatus] Suggested answer: Test tube magnesium nitrate, calcium nitrate No response given / wrong response

SCORE 3

2

1

0

3(e) KK051204 – Technique /Precedure EXPLANATION [Able to state a complete experimental procedure] Suggested answer: 1. 2 cm3 of solution A is poured into a test tube. 2. A few drops of aqueous ammonia solution are added into the test tube using a dropper and the test tube is shaken well. 3. If the precipitate is formed, aqueous ammonia solution is added continuously until no further change occurred / until excess 4. The mixture is shaken well. 5. The changes occur is recorded in a table. 6. Steps 1 to 4 are repeated using solution B.

SCORE 3

[Able to state a complete experimental procedure] 1,2,3,4,5

2

[Able to state a complete experimental procedure] 1,2,3,5 No response given / wrong response

1

20

0

3(f) Tabulation of data EXPLANATION [Able to exhibit the tabulation of data correctly ] Reagent

SCORE

Observation Test tube/Solution A Test tube/Solution B

Aqueous ammonia solution

3

[Able to exhibit the tabulation of data less accurately ] Reagent Aqueous ammonia solution

Test tube /Solution A

2 Test tube/Solution B

[Able state an idea about the tabulation of data]

1

No response given / wrong response

0

END OF MARKING SCHEME

21