Name :

Class :

SMK CONVENT, ALOR SETAR

KEDAHMID YEAR EXAMINATION 2011

Form 4

CHEMISTRY

Paper 2

Two hours and thirty minutes

This question paper consist of 11 printed pages

Section A[60 marks]

Answer all questions in this section.

The time suggested to complete Section A is 90 minutes

Section B (20 marks)Answer any one questionThe time suggested to complete Section B is 30 minutes.

8.

(a)Explain why 16 g of oxygen occupies the same volume as 22 g of carbon dioxide at room condition.

[ 4 marks ]

(b)Based on the information above,

Determine the empirical formula and molecular formula of caffeine.

[8 marks]

(c)Calculate the percentage of nitrogen by mass in each of the three fertilizers given above and hence determine the best fertiliser a farmer should used for his plants.

[ 8 marks ]

Section C (20 marks)Answer any one question.

The time suggested to complete Section C is 30 minutes.

9(a)(i)Table 8.1 shows the atomic radii and melting points of part of group 18 elements.

Jadual 8.1 menunjukkan jejari atom dan takat lebur sebahagian unsur18

kumpulan .

Group 18 Elements

Unsur Kumpulan 18 Physical Properties

Sifat FizikAtomic radius/ nm

Jejari atom / nm

Melting Point / oC

Takat Lebur /oC

Helium

Helium0.050

-270

Neon

Neon0.070

-248

Argon

Argon0.094

-189

Krypton

Krypton0.109

-156

Table 8.1By referring to the table, describe and explain the trend of change in the physical properties of the Group18 elements as we down the group in the Periodic Table.

[6marks]

(ii)Give the uses of the Group 18 elements in table 8 in our daily life.

[4marks]

(b)(i)

Explain why Group 18 gases are monoatomic whereas Group 17 gases are diatomic.

[3marks]

(ii)

Describe briefly the chemical reactivity of group 17 elements as we go down the group in the Periodic Table.

[4marks]

(iii)

Draw the electron arrangement of the compound formed when chlorine reacts with sodium and name the chemical bond in this compound.

[ Proton Number : Na ; 11, Cl ; 17 ]

[3marks]

10 (a)

Explain the above statement.

Given that relative molecular mass of carbon dioxide = 44 g mol 1,

relative molecular mass of oxygen = 2 g mol 1

[3 marks]

(b)(i)What is meant by empirical formula?

[ 1 mark](ii) Describe an experiment in the laboratory to determine the empirical formula of magnesium oxide. Your answer should consist of the following.

Procedures of the experiment

Calculation involved

Precautions need to be taken

Given that relative atomic mass of Mg = 24, O = 16

[13 marks]

(c)Magnesium can reduced copper oxide to copper.Explain why the empirical formula of the copper oxide cannot be determined by heating the mixture of copper oxide and magnesium powder.

[ 3 marks]

**********************************Good Luck****************************

PREPARED BY,

(PN NORZAWATI BT NOORDIN)CHECKED BY,

(PN SHAKINA BT SHAMSUDDIN)Head of Science Panel,

SMK Convent, Alor Setar, Kedah

4541/2

Mid Year Exam

2011

Paper 2

2 hours

SectionQuestionFull

MarksMarks

ObtainedA11121135410510613B720820C9201020Total

DO NOT OPEN THE QUESTION PAPER UNTIL YOU ARE TOLD TO DO SO

[ 4 marks]

[ 2 marks]

4.

5.

6.

[ 2 marks]

7.

3 marks

1 mole of any gas occupies 24 dm3 at room condition.

Caffeine is one of the substances in coffee. 0.97 g of caffeine consists of 0.48 g carbon, 0.05 g hydrogen, 0.28 g nitrogen and 0.16 g oxygen. The molar mass of caffeine is 194 g mol 1.

Fertilisers usually have a high content of nitrogen. Nitrogen is needed to increase the growth of plants such as vegetables. The following substances are the examples of fertiliser which are used by farmers .

Ammonium suplhate, (NH4)2SO4

Urea, CO(NH2)2

Hydrazine, N2H2

The volume of 2.2 g of carbon dioxide gas is less than the volume of 2.2 g of hydrogen at the same temperature and pressure.

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