KIMIA SET 4 Perfect Score

Set 4 Chemistry Perfect Score Module 2007

1

PAPER 2 : STRUCTURESECTION A

1 The diagram shows the chemical reaction of propanol.

D E

II

I

III

Heat gently with ethanoic acid andIV concentrated sulphuric acid

(a) (i) Name process reaction I

………………………………………………………………………………………………………….[ 1 mark ]

(ii) Write the general formula of compound E.

………………………………………………………………………………….................................[ 1 mark ]

(b) (i) Name process II.

………………………………………………………………………………….................................[ 1 mark ]

(ii) What is the catalyst used in process II?

…………………………………………………………………………………..................................[ 1 mark ]

(c) Describe a chemical test to distinguish compound D and E.

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….[ 3 marks ]

(d) (i) Name a chemical used in process III to convert the propanol to propanoic acid.

…………………………………………………………………………………………………………..

[ 1 mark ](ii) What is the observation in process III?

…………………………………………………………………………………………………………..[ 1 mark ]

(iii) Propanoic acid can reacts with magnesium. Write the chemical equation for the reaction.

…………………………………………………………………………………..................................[ 1 mark ]

C3H8 C3H6

Y

Propanol Propanoic acid


2

(e) (i) A compound Y is formed in process IV. Name the compound Y

..........…………………………………………………………………………………..................................[ 1 mark ]

(ii) What is the function of concentrated sulphuric acid in process IV?

…………………………………………………………………………………………………………………..

[ 1 mark]

2 The diagram below shows the flow chart for the conversion of an organic compound to othercompounds through process I, II ,III and combustion of compound L.

IIIAcidified potassium dicromate(VI) solution

I II

Complete combustion in air

(a) (i) Name the homologous series to which L belong.

………………………………………………………………………………….................................[ 1 mark ]

(ii) Name gas X.

…………………………………………………………………………………..................................[ 1 mark ]

(iii) Write a balanced equation for the combustion of L in air

…………………………………………………………………………………..................................[ 2 marks ]

(iv) 0.5 mole of L burn completely in the air. Calculate the volume of gas X released.(1 mole of gas occupies 24 dm

3at room temperature and pressure)

[ 2 marks ]

(b) What is the observation on acidified potassium dichromate(VI) solution in reaction III?

…………………………………………………………………………………………………………..[ 1 mark ]

Compound JC2H6O

Compound KC2H4O2

Compound LC2H4

Gas X + H2O


3

Reflux with compoundX and concentratedsulphuric acid

(c) Compound J reacts with compound K to form compound M.

(i) Name compound M.

…………………………………………………………………………………………………[ 1 mark]

(ii) Draw the structural formula of M.

[ 1 mark ](iii) State one special characteristic of compound M.

…………………………………………………………………………………………………[ 1 mark ]

(d) Draw the set up of apparatus used in process II.

[ 2 marks ]

3 The diagram below shows the chemical reaction of compound X.

IPorous pot chips

Acidified potassium manganate (VII)solution II

III

as

(a) Name compound X.

…………………………………………………………………………………………………………..[ 1 mark ]

Compound X,C2H6O

Compound Y,C2H4O2

Gas Q

Compound Z + water


4

(b) (i) Name gas Q.

…………………………………………………………………………………………………[ 1 mark ]

(ii) What is the use of porous pot chips in process I?

….................................................................................................................................[ 1 mark]

(c) (i) What is the observation on potassium manganate(VII) solution in process II?

…………………………………………………………………………................................[ 1 mark ]

(ii) Draw the structural formula of Y.

[ 1 mark](d) The mixture of compound X, Y and concentrated sulphuric acid are heated under reflux in

process III.

(i) What is the use of concentrated sulphuric acid?

…………………………………………………………………………………………………[ 1 mark ]

(ii) Write a balanced chemical equation for the reaction.

…………………………………………………………………………………………………[ 1 mark ]

(iii) State one special characteristic of compound Z.

…………………………………………………………………………………………………[ 1 mark]

(iv) X is replaced with butanol. Name the product formed.

…………………………………………………………………………………………………[ 1 mark ]


5

4 The diagram below shows the flow chart for the conversion of C2H4 and C3H7OH to other compounds.

a) Name process I.

………………………………………………………………

b) Draw the structural formulae of C2H4 and compound Ppolymerisation of C2H4.

.

c)(i) Name process 2.

………………………………………………………………

(ii) Acidified potassium dichromate(VII) solution is used inchange of acidified potassium dichromate(VI) solution.

…………………………………………………………………

d) Name the product formed from the dehydration of C3

……………………………………………………………………

e) The products from process 1 and process 2 react to f

(i) Name the process for the formation of the compound.

………………………………………………………………

(ii) Draw the structural formula of the compound.

(iii) Name the compound.

………………………………………………………………

C2H5OH

C2H4

Compound P

Process 1

Polymerization

Polymerisation

C2H4

C2H5 COOH

C3 H7OH

Process 2

……

in

……

proc

……

H7O

…

orm

……

……

…………

the equat

…………

ess 2. St

…………

H

……………

a sweet s

…………

…………

C 3 H6

Com

……………………………...........[ 1 mark]

ion below to represent the

[ 2 marks]

………………………………........[ 1 mark]

ate the observation on the colour

…………………………………....[1 mark]

…………………………………[1 mark]

mell compound.

…………………………………[1 mark]

[ 1 mark]

……………………………………[1 mark]

pound P


6

f) C3 H6 in the above diagram undergoes polymerisation. Name the polymer formed.

…………………………………………………………………………………………………………………[1 mark]

g) The boiling point of C3H6 is higher than C2H4. Explain why.

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………..

…………………………………………………………………………………………………………………[3 marks]

5 The diagram shows an industrial preparation of compound X from suphuric acid and ammonia.

(a) (i) Sulphur dioxide is produced at the stage I of contact process.Name the reactants for the formation of sulphur dioxide.

……………………..…………………………………………………………………...........[1 mark]

(ii) Write a chemical equation for the reaction in (a) (i)

……………………..…………………………………………………………………...........[1 mark]

(b) In Contact Process, oleum is produced.

(i) Write the chemical equation for the formation of oleum.

………………………………………………………………………………..........................[1 mark]

(ii) How is sulphuric acid produced from oleum?

……………………………………………………………………………............................. [1 mark]

(c) Name the catalyst used in Contact Process.

………………………………………………………………………………………………………….[1 mark]

Contact Process Suphuric acid

Compound XReaction A

Haber Process Ammonia

Set 4 Chemistry Perfect Score Module 2007(d) (i) Write the chemical equation for the formation of ammonia in Haber Process

....................................................................................................................................[1 mark]

(ii) State the temperature, pressure and catalyst used in the Haber Process.

....................................................................................................................................[1 mark]

(e) In the above diagram, sulphuric acid reacts with aqueous ammonia to form compound X.

(i) Name the reaction A.

...................…………………………………………………………………........................[1 mark]

(ii) Write the chemical equation for reaction A.

……………………………………………………………………………............................[1 mark]

(iii) What is the use of compound X in daily lives?

………………………………………………………………………....................................[1 mark]

6.

(a) Name the main

…………………

(b) What type of p

…………………

(c) Draw an arran

(i) Pu

Bronze and pewter are two example of an alloy.Bronze is made up of copper as a major component and otherelements.

7

element added to copper to form bronze.

………………………………………………………………………………………………….[1 mark]

articles is present in pure copper?

…………………………………………………………………………………………………[1 mark]

gement of the particles in

re copper

[1 mark]

Bronze is harder than pure copper.


8

(ii) bronze

[1 mark]

(d) Explain why is bronze is harder than pure copper?

..............................................................................................................................................................

..............................................................................................................................................................

..............................................................................................................................................................[3 marks]

(e) (i) Name the major component of pewter.

...............................................................................................................................................................[1 mark]

(ii) Beside hardness, state another purpose of alloying to produce pewter.

..............................................................................................................................................................[1 mark]

7 The table shows the examples and uses of four types of manufactured substances in industry.

Type of manufacturedsubstance

Example Component

P Reinforced concrete Cement, sand, small pebbles andsteel.

Alloy Brass Copper and zinc

Polymer S Vinyl chloride

(a) (i) Name the type of substance P.

………………………………………………………………………………………….......…………………[ 1 mark]

(ii) Concrete in an important component in construction. Suggest how the strength of concrete isincreased to be used as a pillars of building.

………………………………………………………………………………………………………………..[ 1 mark]


9

(b) The diagram shows the structure of S.

H H H H H

C C C C C H Cl H Cl H

Draw the structural formula for monomer S.

[1 mark

]

(c) The diagram below shows an industrial preparation of sulphuric acid by the Contact Process.

(i) Name compound X and Y.

Compound X :.............................................................................................................

Compound Y : ...............................................................................................................[ 2 marks]

(ii) Write the chemical equation for the reaction between sulphur and oxygen to produce sulphur dioxide.

.......................................................................................................................................[1 markah]

Sulphur Sulphurdioxide +oxygen

Sulphur trioxide

Compound YSulphuric acid

Compound X, 1 atm

450oC – 500

oC

500oC

ConcentratedH2SO4


10

8 Diagram A shows the structural formula of a detergent and a soap.

Part P Part Q Part P Part Q

Detergent Soap

(a) Name part P and part Q of the detergent and soap molecules.

…………………………………………………………………………………………………………..[ 1 mark]

(b) Differentiate the detergent and soap molecule the aspect of:

Detergent SoapName of part Q

Sources

Effectiveness in hard water

[ 3 marks]

(c) Some of detergent are not biodegradable .What is meant by not biodegradable?

…………………………………………………………………………………………………………..[ 1 mark]

9 Soap, detergent, food additive and modern medicine are important chemicals for consumer.

a) The diagram shows the structural formula of a soap

i) State the property of hydrophobic and hydrophilic p

.................................................................................

……………………………………………………………

ii) Detergent is more effective cleaning agent in hard w

……………………………………………………………

……………………………………………………………

……………………………………………………………

O//

CO- Na+

CH 2

CH3

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2 CH2

Hydrophobic

C-O- Na+

||
O
art of soap molecule.

.......................................................................

………………………………..........................[2 mark]

ater than soap. Explain why.

…………………………………………………..

…………………………………………………..

………………………………………………..…[2 marks]

Hydrophilic


11

b) Preservative and antioxidant are two types of food additive.i) State the function of antioxidant

………………………………………………………………………………………………………………..[ 1 mark]

ii) Give one example of food preservative.

………………………………………………………………………………………………………………..[ 1 mark]

c) What is the type of medicine should be given to a patient who is stress and depressed .Give an example of the medicine.

i) Type of medicine:

………………………………………………………………………………………………………………..[1 mark]

ii) Example of medicine:

………………………………………………………………………………………………………………..[1 mark]


12

ESSAY SECTION B

10 (a)

(i) Explain the cleansing action of soap on greasy stains.[6 marks]

(ii) Explain why detergent is more effective than soap as a cleansing agent in hardwater. [5 marks]

(b)

(i) What is meant by `analgesic`? [1 mark]

(ii) State two examples of analgesics besides aspirin. [2 marks]

(iii) Discuss four uses of aspirin and two side effects on health of using aspirin.[6 marks]

11 (a) Alcohol Q contains 52.2% carbon, 13.0% hydrogen and 34.8% oxygen by mass.(i) Determine the empirical formula and molecular formula of alcohol Q if the

molar mass of alcohol Q is 46 gmol-1

.Relative atomic mass of H=1, C=12 dan O=16 [6 marks]

(ii) Draw the structural formula of alcohol Q. [1 mark]

(b) Describe how you could produce alcohol Q from glucose, C6H12O6.[8 marks]

(c) Describe how you could produce an acid from alcohol Q in the laboratory. In your answer,include the chemical equation for the reaction involved.

[5 marks]

Soap and detergent are two cleansing agents that we used in ourdaily life.

Aspirin is an example of analgesic that should never be givento children.

Set 4 Chemistry Perfect Score Module 2007ESSAY SECTION C

12 (a)

(i) State three uses of sulphuric acid. [3 marks]

(ii) Describe the process of producing sulphuric acid in industry. [7 marks]

(b) .

Describe how you could compare the rate of rusting between iron, steel and stainless steel.Your answer should include tabulation of data and conclusion.

[10 marks]

13 Diagram below shows the convertion of organic compound X to Z and organic compound X

to Y.

a) Compound X ca

(i) Wha

(ii) Draw

b) Gas Y can be ob

Describe how yo

(i) a lab

(ii) nam

(iii) a tes

c) Compound X ca

(i) Name c

(ii) Write th

(iii) Name th

State two

Sulphuric acid is an example of manufactured substance in industry that hasmany uses in our daily life.

Steel and stainless steel are examples of alloys and their major metal is iron.

Z

13

Oxidation

n form a few isomers.

t is meant by `isomer`?

the structural formulae and name all the isomers of compound X.

[5 marks]

tained from compound X through dehydration reaction.

u could produce gas Y from compound X. In your answer, include

elled diagram to show the set-up of apparatus

e of gas Y

t to confirm the presence of gas Y.

[10 marks]

n be oxidized to compound Z. Compound X can react with Z to produce an ester.

ompound Z.

e chemical equation for the oxidation of compound X.

e ester that is formed from reaction betwen X and Z.

physical properties of the ester.

[5 marks]

X(C3H7OH)

GasY

Dehydration


14

Paper 3

14 The diagram below shows the apparatus set-up for an experiment to compare the elasticity properties ofvulcanised rubber and unvulcanised rubber.

An experiment is carried out using weights of 10g, 20g and 30g to get the increase in length of thevulcanised rubber and the unvulcanised rubber.The table below shows the results obtained from the experiment.

Types of rubber Vulcanisedrubber

Unvulcanisedrubber

Weights (g) 10 20 30 10 20 30

Initial length, l1 (cm) 8 8 8 8 8 8

Length after stretching, I2 (cm) 10 12 11 12 16 20

Increase in length, I2 –I1 (cm)

Increase in length after weight is removed. (cm) 8.5 9 9.5 10 12 14

a) Complete the table above based on the above experiment.[3 marks]

b) State one hypothesis for this experiment.

…………………………………………………………………………………………………

………………………………………………………………………………………………....

…………………………………………………………………………………………………[3 marks]

Rubber strip

Clip

Weight

Ruler


15

c) Based on the information above, complete the following table.

Name of variables Action to be taken(i) Manipulated variable:

……………………………………..

……………………………………..

(i) The way to manipulate variable:

………………………………………..

………………………………………...

(ii) Responding variable:

……………………………………

……………………………………

(ii) What to observe in the responding variable:………………………………………..

………………………………………..………

(iii) Controlled variable:

……………………………………..

……………………………………..

(iii) The way to maintain the controlled variable:

………………………………………

………………………………………

[6 marks]

d) i) Based on the experiment above, which rubber strip is more elastic?

…………………………………………………………………………………………………………..[3 marks]

ii) Explain your answer in (d) (i).

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..[3 marks]

e) Give the definition of vulcanised rubber?

…………………………………………………………………………………………………………………….

…………………………………………………………………………………………………………………….[3 marks]

15

Referring to the above situation, plan an experiment in the laboratory to investigate the effect of alloyingtowards the hardness of pure metal.Your planning should include the following:(i) Statement of the problem(ii) Hypothesis(iii) Variables(iv) List of substances and apparatus(v) Procedures(vi) Tabulation of data [17 marks]

Copper wire in an electric cable can be bent with our bare hands. One cent shilling made fromthe alloy of copper with tin and zinc cannot be bent easily.


16

Sample Answer

1(a) (i) Dehydration 1

(ii) CnH2n+2 1(b) (i) Hydrogenation / addition with hydrogen

(ii) Nicel/Platinum 1(c) Add bromine water and shake 1

E decolourises the brown colour of bromine water.D does not change the brown colour of bromine water. 1

(d) (i) Acidified potassium manganate(VII)/ Acidified potassium dichromate(VI) 1(ii) Purple to colourless / orange to green. 1(iii) C2H5COOH + Mg (C2H5COO) 2Mg + H2

(e) (i) Propyl ethanoate 1(ii) Catalyst

2 (a) (i) Alkene 1(ii) Carbon dioxide 1(iii) C2H4 + 3O2 → 2CO2 + 2H2O 1+1(iv)

1 mol C2H4→2 mol CO2 //0.5 mol C2H4 → 1 mol CO2 1

Volume of gas X / CO2 = 1 x 24 dm3

// 24 dm3

1

(b) Orange to green 1( c) (i) ethyl ethanoate 1

(ii) O//

CH3-C – O – C2 H5 1

(iii) sweet smell 1

(d) Functional diagram 1Label 1

12

3 (a) ethanol 1(b) (i) ethane 1

(ii) Functional diagram 1Label 1

(c) (i) Purple to colorless 1(ii)

H O

H - C - C-O-H 1

H(d) (i) catalyst 1

(ii) CH3CH2OH + CH3COOH CH3COOCH2CH3 + H2O 1(iii) sweet smell 1(iv) butyl ethanoate 1

10


17

4a) Hydration

b)

1c) (i) Oxidation 1

(ii) Orange of to green 1d) Propane 1e) (i) Esterification 1

(ii)

1(iii) Ethyl propanoate 1

f) Polypropane 1g) The size of propane molecule is larger than ethane molecule 1

The intermolecular forces between propane molecules stronger than ethane 1More energy is needed to overcome the forces between propane. 1

5 a(i)(ii)

b (i)(ii)c

d (i)ii)

e (i)

(ii)

(iii)

Sulphur and oxygen gasS + O2 SO2

SO3 + H2SO4 H2S2O7

Dissolve SO3 in concentrated sulphuric acidVanadium(v) oxide

3H2 + N2 2NH3

[450oC], [200 atm], Iron

Neutralization

H2SO4 +2 NH4OH (NH4)2SO4 +2H2O

Fertilizer

11

111

11

1

1

1

6(a) Tin(b) Atom(c) (i) (ii)

(d) 1. Atoms of pure copper metal are the same size, they arranged orderly in layered pattern.2. Layers of atoms are easily slide over each other when external force is applied on them.

3. Foreign atoms in alloy disrupt the orderly arrangement of metal atoms

Copper atomCopper atom

Tin atom

n

n

C C

H H

H H

C C

H H

H H

C O H

O

C C

H H

H H

H


18

4. Layers of metal atoms are prevented from sliding each other when external force is applied.

(e) (i) Tin

(ii) Improve appearance / prevent corrosion.

7 a) (i) Composite material(ii) Add steel

b) H H

C=C

H Cl

f) (i) X : vanadium (v) oxide

Y : Oleum

(ii) S + O2 SO2

11

1

1

1

1

1

6

8 (a) hydrocarbon/ hydrophobic 1(b)

Soap DetergentName of part Q Carboxylate Sulphonate

Sources Oil petroleum

Effectiveness in hard water Not effective Effective

1+1+1

(c) Cannot decomposed by microorganism 11

9 a)i) Hydrophobic dissolve in organic solvent

Hydrophilic dissolve in waterii) Soap forms scum with the presence of magnesium ion and calcium

ion.Detergent does not form scum in hard water.

iii) Not biodegradable.

b) (i) Prevent food from being oxidized by oxygen in the oxygen in the air.(ii) sodium benzoate

c) (i) Antidepressant(ii) Tranquilizer / Barbiturate

111

11

1

1

11

9


19

SECTION B

10 (a) (i) 1. Soap anion consists of hydrophilic and hydrophobic. 12. Hydrophilic dissolves in water. 13. Hydrophobic dissolves in oils/grease. 14. Soap reduces surface tension of water. 15. Hydrophobic emulsify oil or grease. 16. During rinsing, soap will remove the grease 1….6

(ii) 1. Hard water contains calcium ions/Ca2+

and magnesium ions/ Mg2+

12. Soap anions react with calcium ions/Ca

2+or magnesium ions/

Mg2+

to form scum 13. Scum is insoluble in water 14. Waste soap 15. Detergent does not form scum 1....5

(b) (i) Medicine used to relieve pain without causing numbness oraffecting consciousness 1…1

(ii) Paracetamol 1Codeine 1…2

(iii) 1. Relieves pain caused by headache, toothache2. Reduces fever3. Treat arthritis /reduce inflammation of the joints4. Reduces blood clotting / prevents stroke / prevents heart

attacksa. Reduces inflammation caused by infection or injury

(any four) 1+1+1+1....4

1. Causes internal bleeding of the stomach / Ulceration2. Causes brain / liver damage if given to children3. Overdose causes death

(any two) 1+1....220

11(a) Element C H O

1. Number of moles 52.2 13.0 34.8 1of atoms 12 1 16

=4.35 =13.0 =2.1752. Ratio 2 6 1 1

3. Empirical formula of Q is C2H6O 1Relative molecular mass of (C2H6O) n = 46

4. 2n(12) + 6n(1) + n(16) = 46 146n = 46

5. n = 1 16. Molecular formula of Q is C2H6O / C2H5OH 17. Structural formula is

H H

H - C - C -OH H H 1....7


20

(b) 1. Add glucose into a conical flask. 12. Add water. 13. Add yeast. 14. Close the conical flask 15. Leave the flask for 1 to 3 days. 16. Filter the content 17. Distille the filtrate 18. Collect the fraction that boils at 78 -80

0C 1....8

(c) 1. Add alcohol Q in a test tube. 12. Add acidified potassium manganate (VII) solution 13. Heat the solution. 14. The purple colour of the solution turns colourless 15. [Chemical equation] 1....5

20

SECTION C12 ( a)(i) 1. Manufacture fertilisers

2. Manufacture detergents

3. As an electrolyte in car batteries

4. Manufacture paint pigments

5. Synthetic fibres

6. Plastics

7. Clean metals

8. Pesticides

[any 3 above] 1+1+1....3

(ii) 1. Sulphur is burnt in the air // Zinc sulphide is burnt to produce sulphur

dioxide // Equation

S + O2 SO2 //

2ZnS + 3O2 2ZnO + 2SO2 1

2. Sulphur dioxide react with oxygen to produce sulphur trioxide // Equation

2SO2 + O2 2SO3 1

3. Catalyst: vanadium(V) oxide 1

4. Temperature: (400 – 500oC) 1

5. Pressure: 1 atm 1

6. Sulphur trioxide reacts with concentrated sulphuric acid to produce

oleum // Equation:

SO3 + H2SO4 H2S2O7 1

7. Oleum is diluted with water to produce sulphuric acid // Equation

H2S2O7 + H2O 2H2SO4 1..7

b) 1. Material: iron nail, steel nail, stainless steel nail, jelly solution, potassiumhexacyanoferrate(III) solution 1

2. Apparatus: Test tubes, test tube rack 1

3. Put iron nail in test tube A, steel nail in test tube B and stainless steel intest tube C 1

4. Add jelly solution and a few drops of potassium hexacyanoferrate(III)solution into the test tubes 1

5. Pour the jelly solution until the nails are fully immersed 16. Leave the test tubes for 2-3 days 1


21

7. Observation 1

Test tube Intensity of blue colour

A (Iron nail) High

B (Steel nail) Low

C (Stainless steel nail) Nil

8. Potassium hexacynoferrate(III) solution to detect iron(III) ions 1

9. The higher the intensity of the blue colour, the higher the rate of rusting 1

10. Rate of rusting of iron is the highest follow by steel and stainless steel

does not rust 1..10

20

13(a) Isomers are molecules/compounds which have same molecular

formulae but different structural formulae.

H H H H OH H│ │ │ │ │ │

H─C─ C ─ C─ OH H – C─ C ─ C ─ H│ │ │ │ │ │H H H H H HPropan-1-ol Propan-2-ol

1

1+11+1..5

(b) 1. Functional set-up of apparatus2. Label3. Place the glass wool in a boiling tube. Add propanol/C3H7OH to the

glass wool.4. Place the porcelain chips in the tube.5. Heat the porcelain strongly.6. Heat the glass wool.7. Collect gas Y using test tube.8. Gas Y is propene.9. Add bromine water (acidified potassium manganate(VII) solution) to

the test tube.10.Brown colour of bromine decolourised (purple colour of potassium

manganate(VII) decolourised)

11

111111

1

1..10

(c) (i)(ii)

X –propanoic acidC3H7OH + 2[O] → C2H5COOH + H2O

11

(iii) Ester –propyl propanoate

Sweet pleasant smell (fruity smell)Less dense than waterInsoluble in waterColourless liquidVolatile(any two)

1

1+1..520


22

Paper 3

14 (a) To measure using numbersScore Explanation3 Able to record all the six readings correctly.

Suggested answerVulcanised rubber: 2, 4, 6Unvulcanised rubber: 4, 8, 12

1(b) To make hypothesisScore Explanation3 Able to relate between the manipulated variable and the responding variable.

Suggested answerVulcanised rubber is more elastic than the unvulcanised rubber// Unvulcanised rubber isless elastic than the vulcanised rubber

1(c) To control variableScore Explanation

6Suggested answer

Variable Action to be taken(i) Manupilated variable

Vulcanized and unvulcanizedrubber// Mass of weight

(i) The way to manupilate variableRepeat by replacing vulcanized rubber withunvulcanized rubber//Use weights withdifferent masses

(ii) Responding variableIncrease in length of rubberstrip//elasticity

(ii) What to observe in the responding variable

To measure length of rubber strip

(iii) Fixed variableInitial length of rubber strip

(iii) The way to maintain the controlled variable

Use the same length of vulcanized andunvulcanized rubber strips

1(d) To make inferenceScore Explanation3 Able to make the correct inference

Suggested answer:(i) Vulcanized rubber(ii) Presence of the sulphur cross links between the chain of rubber polymers in

vulcanized rubber makes the small increase in length and can return to itsoriginal length after stretching.

1(e) Operational definition:Score Explanation3 Able to make an operational definition correctly:

Suggested answer:Rubber that can stretch a bit and returns to its original length when not stretched.


23

15Rubric Scor e

(i) [Able to give the correct problem statement.]Suggested answer:How does alloying affects the hardness of metal?//What is the effect ofalloying towards the hardness of metal?

3

(ii) [Able to state all the variables correctly]Suggested answer:Manipulated variable: metal and its alloy//copper and brass/bronze// iron

and steel

Responding variable: size/diameter of dentFixed variable : Mass of weight//height of weight//type of metal of

ball bearing// size of ball bearing

3

(iii) [Able to list completely the substances and apparatus]Example:Metal (named), its alloy(named)Steel ball bearing, weight, ruler, rope/thread, retort stand

3

(iv) [Able to state the procedures correctly]Example:

1. Put a ball bearing on a metal block/its alloy.2. Hang a weight until (50-100 cm) above the metal block/its alloy3. Let the weight fall.4. Measure and record the diameter of the dent formed.5. Repeat the activity a few more times6. Repeat steps 1 – 5 by replacing the metal with its alloy// alloy wits

metal

3

(v) [Able to show the correct tabulation of data]Table with the following elements:

1. 4 colums and 3 rows2. Titled metal (named), its alloy (named), diameter (with unit),

Average (with unit)Example

Diameter (cm) Average(cm)1 2

Metal (named)Alloy(named)

3

KIMIA SET 4 Perfect Score

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Transcript of KIMIA SET 4 Perfect Score