AKUEB SSC-II Chemistry Paper II Composite '08

8/9/2019 AKUEB SSC-II Chemistry Paper II Composite '08

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AGA KHAN UNIVERSITY EXAMINATION BOARD

SECONDARY SCHOOL CERTIFICATE

COMPOSITE EXAMINATION 2008

Chemistry Paper II

Time allowed: 2 hours 20 minutes Marks 55

Candidate Name

School

INSTRUCTIONS

Please read the following instructions carefully.

1. Check your name and school information. Sign that it is correct.

2. Write the number of the seat in which you are sitting.

3. RUBRIC. There are NINE questions. Answer ALL NINE questions. Questions 7, 8 and 9 offer

choices, answer any one choice from each.

4. When answering the questions:

Read each question carefully.

Use ONLY black ink.

Do not use staples, paper clips, glue or correcting fluid.

DO NOT write outside the answer box.

Complete your answer in the allocated space only.

5. The marks for the questions are shown in brackets ( ).

6. You may use a simple calculator if you wish.

I agree that this is my name and school.

Candidate's signature


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Q.1. (Total 7 Marks)

a. OH2OH2 222 +

i. What do we call hydrogen and oxygen in the above chemical equation? (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

ii. How many coefficients are there in the above chemical equation? (1 Mark)

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___________________________________________________________________________________

b. Fluorine combines with hydrogen and potassium separately to form two different compounds.

(1) HF (Hydrogen Fluoride)(2) KF (Potassium Fluoride)

Classify the compounds as either ionic or covalent giving reasons. (2 Marks)

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___________________________________________________________________________________

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PLEASE TURN OVER THE PAGE

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c. (3 Marks)

0

10

20

30

40

50

60

70

80

90100

1 2 3 4 5 6 7 8 9 10

Time (min)

Temperature(C)

i. What is the melting point of the substance? (1 Mark)

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___________________________________________________________________________________

ii. Explain the change in temperature when the substance is melting? (1 Mark)

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___________________________________________________________________________________

iii. Explain the change in temperature when the substance is completely melted? (1 Mark)

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a. Why has the mole fraction no unit? (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

b. Draw the Lewis model of HCl and .NH3 (2 Marks)

Space for diagram

c.

What is the mass number? (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

Ip

2n

e


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a. Complete the flow chart (Chemical reaction) for the preparation of sodium silicate. (2 Marks)

2SiO

+

?

+

b. A gas jar contains a greenish yellow gas. When a green leaf was brought near the gas jar the leaf

bleached and lost its colour.

i. Identify the gas present in the gas jar. (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

ii. Write down the chemical reaction for the laboratory preparation of this gas. (2 Marks)

___________________________________________________________________________________

___________________________________________________________________________________

iii. Write any two uses of hydrochloric acid. (2 Marks)

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

Na2SiO3 ?


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c. The diagram below shows a model of a methane molecule.

i. Describe a methane molecule. (2 Marks)

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___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

ii. How can you conclude that methane is a fuel? (1 Mark)

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___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

H

C

HH

H


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a. Define international system. Give any one importance of S.I units. (2 Marks)

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

b. When a piece of sodium is dropped in water from a storage bottle containing oil it vigorously

reacts producing a gas.

i. Why was the sodium kept in oil? (2 Marks)

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

ii. What gas was given off during the reaction? (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

pair of tongs

Sodium

water


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c. One metal can be coated with another by setting up electrodes and electrolytes. The process is

called electroplating.

i. Identify the electrode to be plated (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

ii. What is meant by an electrolyte? (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

iii. Write down the reactions at the cathode for both copper and nickel plating. (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

Cathode

BeakerAnode

Electrolyte


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a. OHCOKCldilHClCOK 2232 2)(2 +++

When potassium carbonate powder is added to dilute HCl acid in a beaker the mixture fizzes up and

feels cold.

i. Is this a physical or chemical change? Is this reaction exothermic or endothermic?

(1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

ii. Draw an energy graph for this reaction (1 Mark)

Space for diagram


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b. The diagram below shows the fractional distillation of air. Air is liquefied by compressing

and cooling it, then it is allowed to warm up. Different gases are collected at different

boiling points. (2 Marks)

How is air liquefied? (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

c. Complete the balanced equations (2 Marks)

+

+

KS

NaS 2

Nitrogen

Oxygen

XenonAir

Kyrpton

Argon -186C -196C

-183C

Pure-152C


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a. Ions are charged particles formed when an atom loses or gains an electron.

Na loses an electron Becomes ion.Na 1+

i. What particular names are given to the positive and negative ions? (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

ii. Why do some atoms have different neutron numbers as compared to their correspondingprotons? (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

Nae

Na+1


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b. The diagram below shows a method for obtaining pure copper from impure copper.

i. Identify the place A, B, C, D or E where (3 Marks)

a. the impure copper is placed at.____________________________________________

b. the solid impurities collect at. ____________________________________________

c. pure copper is formed at. ________________________________________________

One of the reactions which takes place in the process is represented by the equation:

)(2)(2

)( anodeateCuCu aqs +=+

Why is the reaction described as oxidation? (1 Mark)

___________________________________________________________________________________

___________________________________________________________________________________

Impure

copper

(A)

Cathode

Copper

sulphate

solution

(B)

Refining of copper

(C)

Mud

(E

CuSO4

(D)

Anode

- +


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EITHER

a. Define solubility. Describe the factors that influence the solubility of a substance.

OR

b. What are salts? How many types of salts are there? Describe with the help of examples.

___________________________________________________________________________________

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___________________________________________________________________________________

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EITHER

a. Write the balanced chemical equation for the laboratory preparation of chlorine gas.

Describe what happens when chlorine reacts with

i. Hydrogenii. Sulphuriii. Sodiumiv. Potassium iodideSupport your answer with balanced equations.

OR

b. Define a homologous series. State any FOUR characteristics of a homologous series.

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

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END OF PAPER

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EITHER

a. Write the main points of Daltons atomic theory (at least FIVE points).

OR

b. Define soap and explain its FOUR types.

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

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___________________________________________________________________________________

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AKUEB SSC-II Chemistry Paper II Composite '08

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