8/2/2019 Fajar MYE05 5068 S3 Ans

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Fajar Secondary SchoolAns Key End of Year Exam 2005Sec 3 Express Chemistry

Section A 30 marks

1 B 6 C 11 A 16 B 21 C 26 A

2 C 7 C 12 C 17 D 22 D 27 D

3 B 8 B 13 C 18 C 23 C 28 C

4B/D

9 D 14 A 19 B24 C 29 C

5 D 10 A 15 D 20 D 25 C 30 D

Section B

marks total

1 (a) It is the end line, which shows the distance moved bythe solvent 1

(b) Spot A 3/12 = 0.25Spot B 9/12 = 0.75Spot C 11/12 = 0.92

Three correct [2]Two correct [1]One correct [0]

2

(c) No, ink from the note contains 2 other spots which aredifferent from the felt pen.

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2 (a) (i) It means solid ammonium chloride turns into a vapourwithout becoming a liquid.

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(ii) The solid sublimes and condenses as a white solid onthe cooler parts of the test tube.

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(b) (i) 132 C 1

(ii) Liquid and solid

2 correct [1]

(iii) During freezing, heat energy lost by the liquid particlesis used to form force of attraction between them sothat they take up fixed and orderly arrangement.

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2

(c) Diffusion takes place.When the perfume vaporises, its gas particles movefreely to fill up the available spaces between the air

particles / the perfume particles moves from a highconcentration region to a low concentration region.

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8/2/2019 Fajar MYE05 5068 S3 Ans

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3 (a) Movement cannot move, vibrate in fixed positionArrangement packed close together in an orderlyarrangement

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(b) On heating, the solid particles gain heat energy andvibrate faster.Eventually the solid particles have sufficient energy to

overcome the forces holding them to become a liquid.The liquid particles are then slightly further apart (butstill close packed) in a disorderly arrangement.They are able to move throughout the liquid.

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4 (a) Q 1

(b) R 1

(c) U 1

(d) Atoms of element(s) combined together by sharingelectrons

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(e) Because P has a giant macromolecular structurewhere the atoms are joined together by strongcovalent bonds.The rest have simple molecular structure where themolecules are held by weak intermolecular force of

attraction.

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5 (a) Sodium atom 11 11 12Calcium ion 20 18 20Chloride ion 37 17 18

111

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(b) (i)1

(ii) Y2O3 1

6 A CB AC FD D

1111

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13 p14 n

8/2/2019 Fajar MYE05 5068 S3 Ans

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Cl H

7 (a) X - 4Y - 6Z - 1

111

3

(b) XH4

HY2ZH

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Section C

8 (a) (i) 2

(ii) 2

(b) In solid rubidium chloride, the ions are held in fixedposition by strong ionic bond.A large amount of energy is required to break thesestrong forces of attraction to pull the ions apart.Rubidium chloride thus has a high melting point andboiling point and therefore is a solid at roomtemperature

Hydrogen chloride has a simple molecular structure.

The molecules are held together by weakintermolecular force of attraction.A small amount of energy is required to break theseweak forces of attraction to pull the molecules apart.Hydrogen chloride thus has a low boiling point and istherefore a gas at room temperature.

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(c) This element must be an isotope of rubidium as it hassame number of protons but different number ofneutrons as rubidium.Isotopes have similar chemical properties and undergo

similar chemical reactions.

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RbCl

-+

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9 (a) (i) Group I, becauseit is soft and has a silvery appearanceit is extremely reactive with water and air

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(ii) 2Za + 2 H2O 2ZaOH + H2

Obsn:Zarium floats and melts on water/ flame seenZarium reduces in sizeThe alkaline solution (ZaOH) turns Universal indicatorblue.

Any two observations

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(b) (i) Transition elements 1

(ii) Form coloured compounds,

e.g iron (II) chloride solution is pale green in colour /Has variable oxidation state,e.g iron has oxidation states of +2 and +3

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(c) When chlorine gas is bubbled into colourlesspotassium iodide, it turns brown due to the formation

of iodine / Cl2 + KI (aq) 2KCl + I2This happens because chlorine, being more reactive,displaces iodide from its aqueous solution.

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10 (a) (i) Oxygen is a substance that is made up of only onetype of atoms (i.e oxygen atoms)Water is a substance that is made up of two type ofatoms (i.e oxygen and hydrogen atoms) chemicallycombined together.

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(ii) Air has no fixed composition of water vapour andcarbon dioxide, they varied from places to places.Water has a fixed composition of oxygen andhydrogen, no matter where it is .

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(iii) Air can be separated into its components usingphysical method such as fractionally distillation.Water cannot be separated into its components usingphysical method. It can only be separated usingchemical method such as electrolysis.

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(b) (i) C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (l)

Correct balancing [1] Correct state symbols [1]

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8/2/2019 Fajar MYE05 5068 S3 Ans

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(ii) 3HNO2 (aq) HNO3 (aq) + 2NO (g) + H2O (l)

Correct balancing [1] Correct state symbols [1]

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