BaptistLuiMingChoiSecondary School
Name: ______/ F.6 Mock Examination (2012-13) / Date: 20/2/2013Class: ______( ) / Combined Science - Chemistry / Time:8:40–10:20a.m.
INSTRUCTIONS
1. / There are TWO sections, A and B, in this Paper. Section A carries 24 marks and Section B carries 56 marks. You are advised to finish Section A in about 30 minutes.
2. / Section A consists of multiple-choice questions in this question book, while Section B contains conventional questions printed separately in Question-Answer Book B.
3. / Answers to Section A should be marked on the Multiple-choice Answer Sheet while answers to Section B should be written in the spaces provided in Question-Answer Book B. The Answer Sheet for Section A and the Question-Answer Book for Section B must be handed in separately at the end of the examination.
4. / A Periodic Table is printed on the back of the Question-Answer Book B. Atomic numbers and relative atomic masses of elements can be obtained from the Periodic Table.
5. / An asterisk (*) has been put next to the questions where one mark will be awarded for effective communication.
SECTION A (MULTIPLE-CHOICE QUESTIONS)
1. / The following diagram shows an experimental set-up for collecting a gas produced in a certain reaction.Which of the following actions can prevent‘sucking back’ of water?
(1) Take the delivery tube away from water before removing the flame.
(2) Remove the flame before taking the delivery tube away from water.
(3) Decrease the amount of water in the trough.
A (1) only
B (2) only
C (1) and (3) only
D (2) and (3) only
P.T.O.
Form 6 / Combined Science - Chemistry / P.22. / The table shows the melting points and boiling points of four substances at 1 atm pressure.
Substance / Melting point (°C) / Boiling point (°C)
W / –60 / –5
X / –189 / –55
Y / –40 / 60
Z / 5 / 58
Which substance exists as a liquid at –50°C and 1 atm pressure?
AW / BX / CY / DZ
3. / The atomic mass of element X is 114.8. X has two isotopes, 113X and aX, and the relative abundance of 113X is 10.0%. What is the value of a?
A112 / B114 / C115 / D116
4 / Hydrogen and sulphur react to give hydrogen sulphide. Which of the following diagrams can represent the particles in a sample of hydrogen sulphide at room temperature and pressure?
5. / Which of the following combinations is correct?
Substance / Attraction between particles in substance
(1) / Carbon dioxide / Covalent bond
(2) / Silicon dioxide / Covalent bond
(3) / Lead(II) oxide / Ionic bond
A(1) and (2) only
B(1) and (3) only
C(2) and (3) only
D(1), (2) and (3)
To be continued
Form 6 / Combined Science - Chemistry / P.36. / Substance / Melting point (°C) / Electrical conductivity
solid state / molten state
W / 1 565 / non-conductor / conductor
X / 1 610 / non-conductor / non-conductor
Y / 40 / non-conductor / non-conductor
Z / 1 670 / conductor / conductor
Which of the following statements is correct?
AW is malleable.
BX is soluble in heptane (a non-aqueous solvent).
CY is a liquid at room temperature and pressure.
DThe compound formed between Z and chlorine conducts electricity in molten state.
7. / Aluminium is used to make foils used in food packaging because
(1)it is impermeable to gases.
(2)it is the most abundant metallic element in the Earth’s crust.
(3)it is non-poisonous.
Which of the above statements are correct?
A(1) and (2) only
B(1) and (3) only
C(2) and (3) only
D(1), (2) and (3)
8. / Consider the electrolytic cell in the right used to obtain aluminium from aluminium oxide. Colourless gas bubbles are given off from electrode X.
Which of the following statements are correct? /
(1)The electrodes are made of graphite.
(2)X is the positive electrode.
(3)The aluminium ore is dissolved in molten cryolite to increase the strength of aluminium obtained.
A(1) and (2) only
B(1) and (3) only
C(2) and (3) only
D(1), (2) and (3)
P.T.O.
Form 6 / Combined Science - Chemistry / P.49. / Consider the following chemical equation:
5H2S + 2KMnO4 + xH2SO4yS + zH2O + 2MnSO4 + K2SO4
Which of the following combinations is correct?
x / y / z
A / 2 / 5 / 4
B / 3 / 5 / 8
C / 3 / 10 / 4
D / 4 / 10 / 8
10. / X and Y are two different metals.
Which of the following shows that X is more reactive than Y?
AY forms an ion with a charge of +1 while X forms an ion with a charge of +2.
BThe oxide of X can be reduced by carbon but the oxide of Y cannot.
CX can displace Y from an aqueous solution of a salt of Y.
DY reacts with dilute hydrochloric acid but X does not.
11. / A solid mixture of iron(II) nitrate and iron(II) carbonate contains 2.0 moles of nitrate ions and 2.4 moles of iron(II) ions. How many moles of carbonate ions are present in the mixture?
A1.0 mol / B1.4 mol / C1.7 mol / D2.0 mol
12. / Propane (C3H8) can be used as a fuel.
It reacts with oxygen according to the following equation:
C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(l)
22.0 g of propane are allowed to react with 57.6 g of oxygen. What is the mass of carbon dioxide produced?
A22.0 g / B39.8 g / C47.5 g / D66.0 g
13. / One method for extracting zinc from zinc sulphide ore involves first roasting the ore in air and then reducing the oxide obtained to metal with carbon. The process can be represented by the overall equation:
2ZnS(s) + 3O2(g) + C(s) 2Zn(s) + 2SO2(g) + CO2(g)
In a certain plant, the percentage yield of zinc is 86%. What is the amount of zinc that this plant produces per tonne of the zinc sulphide ore? [1 tonne = 1000 kg]
A0.48 tonne / B0.58 tonne / C0.67 tonne / D0.86 tonne
To be continued
Form 6 / Combined Science - Chemistry / P.514. / In which of the following cases will the iron nail rust after 1 week?
A(1) and (2) only
B(1) and (3) only
C(2) and (3) only
D(1), (2) and (3)
15. / The diagram below shows the set-ups for comparing electrical conductivity of dilute solutions of 2 alkalis:100 cm3 of 0.1 mol dm–3 alkali X and 100 cm3 of 0.1 mol dm–3alkali Y.
Which of the following deductions is / are correct?
(1)Alkali X is stronger than alkali Y.
(2)0.1 mol dm–3 alkali X contains less mobile ions than 0.1 mol dm–3 alkali Y.
(3)The pH of 0.1 mol dm–3 alkali X is lower than that of 0.1 mol dm–3 alkali Y.
A(1) only
B(2) only
C(1) and (3) only
D(2) and (3) only
16. / Which of the following pairs of solutions would NOT give a precipitate on mixing?
ANaCl(aq) and MgSO4(aq)
BKCl(aq) and AgNO3(aq)
CNH3(aq) and FeSO4(aq)
DNa2CO3(aq) and Ca(NO3)2(aq)
P.T.O.
Form 6 / Combined Science - Chemistry / P.617. / Solution X is prepared by mixing 100.0 cm3 of 2.50 mol dm–3 Na2CO3(aq) with 150.0 cm3 of 1.00 mol dm–3 NaCl(aq). What is the concentration of Na+(aq) ions in X?
A
B
C
D / 1.25 mol dm–3
1.60 mol dm–3
2.60 mol dm–3
3.25 mol dm–3
18. / Which of the following processes is a redox reaction?
ABaCl2(aq) + Na2CrO4(aq) BaCrO4(s) + 2NaCl(aq)
BFe2(SO4)3(aq) + H2S(g) 2FeSO4(aq) + S(s) + H2SO4(aq)
CCH3COOH(aq) + NaOH(aq) CH3COONa(aq) + H2O(l)
DAl(OH)3(s) + NaOH(aq) NaAl(OH)4(aq)
19. / A solution of potassium sulphate containing litmus solution is electrolyzed using the set-up shown below:
After a short time, which of the following colours would appear in the solutions around the two platinum electrodes?
Around electrode X / Around electrode Y
A / Colourless / red
B / Blue / colourless
C / Red / blue
D / Blue / red
To be continued
Form 6 / Combined Science - Chemistry / P.720. /
Which of the following is the correct combination of the above series of reactions?
P / Q / R / S
A. / Ethanol / K2Cr2O7 / H+ (aq) / Ethanal / Ethanoic acid
B. / Ethanal / K2Cr2O7 / H+ (aq) / Ethanoic acid / Ethyl Ethanoate
C. / Ethene / KMnO4 / H+ (aq) / Ethanoic acid / Ethyl Ethanote
D. / Ethanol / K2Cr2O7 / H+ (aq) / Ethanoic acid / Ethyl Ethanote
.
21. / A student wanted to electroplate a copper knob with nickel using the following set-up.
Which of the following combinations is correct?
Cathode / Anode / Electrolyte
A / Nickel rod / copper knob / NiSO4(aq)
B / Copper knob / nickel rod / NiSO4(aq)
C / Nickel rod / copper knob / CuSO4(aq)
D / Copper knob / nickel rod / CuSO4(aq)
22. / Consider the reaction between iodine and propanone:
I2(aq) + CH3COCH3(aq) CH3COCH2I(aq) + H+(aq) + I–(aq)
Which of the following changes could be used to follow the progress of the reaction?
(1)Acidity of the reaction mixture
(2)Electrical conductivity of the reaction mixture
(3)Colour intensity of the reaction mixture
A(1) and (2) only
B(1) and (3) only
C(2) and (3) only
D(1), (2) and (3)
P.T.O.
Form 6 / Combined Science - Chemistry / P.8Directions: / Each question below (Questions 23 to 24) consists of two separate statements. Decide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of the first statement. Then select one option from A to D according to the following table:
A. / Both statements are true and the second statement is a correct explanation of the first statement.
B. / Both statements are true and the second statement is NOT a correct explanation of the first statement.
C. / The first statement is false but the second statement is true.
D. / Both statements are false.
First Statement / Second Statement
23. / Oxygen is the major product at the anode in the electrolysis of concentrated sodium chloride solution. / Position of hydroxide ion in E.C.S. is higher than that of chloride ion.
24. / can undergo addition polymerization. / is unsaturated.
END OF SECTION A
BaptistLuiMingChoiSecondary School
Name: ______/ F.6 Mock Examination (2012-13) / Marks:______Class: ______( ) / Combined Science - Chemistry / Time: 8:40–10:20a.m.
SECTION B (QUESTION-ANSWER BOOK)
Answer ALL questions. Write your answers in the spaces provided.
1. / T, X and Z are three elements in the periodic table, with the sum of their atomic numbers equal to 37. Moreover, both T and X are Group VII elements, while the atomic number of T is smaller than that of X.(a) / What are the elements T, X and Z?
T: ______/ X:______/ Z:______
(1 mark)
(b) / Draw the electronic diagram, showing electrons in the outermost shells only, of the compound formed from
(i) X and phosphorus / (ii) and X and Z.
(2 marks)
(c) / Explain which compound formed in (b) has higher melting point.
(2 marks)
(d) / State one daily use of element Z.
(1 mark)
(e) / Discuss, with explanation, the electrical conductivity of the compound formed from X and Z with reference to the type and property of the particles in it.
(2 marks)
P.T.O.
1 / 2 / 3 / 4
Final reading (cm3) / 21.70 / 21.70 / 22.40 / 23.50
Initial reading (cm3) / 0.00 / 1.50 / 2.10 / 3.40
(a) / State the colour change of solution at the end point.
(1 mark)
(b) / Write a chemical equation between sodium hydroxide solution and dilute sulphuric acid.
(1 mark)
(c) / (i) / Calculate the reasonable average volume of sodium hydroxide solution used.
(ii) / Calculate the molarity of sodium hydroxide solution used.
(4 marks)
Form 6 / Combined Science - Chemistry / P.2
To be continued
Form 6 / Combined Science - Chemistry / P.32. / (d) / A student suggests that the standard sodium hydroxide solution can be prepared alternatively by dissolving known mass of sodium hydroxide solids into known volume of distilled water. Do you agree with him? Explain.
(1 mark)
* / (e) / Outline the experimental procedure how the dilute 0.1 M sulphuric can be prepared from 1M dilute sulphuric acid.
(4 marks)
(d) / Explain whether polystyrene is suitable for making electrical sockets.
P.T.O.
Form 6 / Combined Science- Chemistry / P.43. / The data below is from an experiment to determine the enthalpy change of the reaction between sodium hydroxide solution and hydrochloric acid.
50.0 cm3 of a 0.500 mol dm−3 solution of sodium hydroxide was mixed rapidly in a glass beaker with 50.0cm3 of a 0.500 mol dm−3 solution of HCl.Initial temperature of solutionsis19.6°C and final temperature of the mixture is23.1°C. Specific heat capacity of water is 4.18 Jg-1°C-1
(a) / Calculate the enthalpy change of this reaction in kJ mol−1. Assume that the specific heat capacity of the solution is the same as that of water.
(2 marks)
(b) / The experiment was repeated with 75 cm3 of a 0.500 mol dm−3 solution of HCl.State and explains the effect on the temperature change.
(3 marks)
To be continued
Form 6 / Combined Science - Chemistry / P.5
3. / (c) / Given that the enthalpy change of reaction between solid sodium hydroxide and hydrochloric acid is -89.4 kJ mol−1. Calculate, with an energy cycle, the enthalpy change when solidsodium hydroxide is dissolved in water completely.
(3 marks)
4. / The following is a record of observations when a black solid X was tested:
Test / Observation
1Heating solid X in hydrogen gas / Solid X slowly turned to a reddish brown metal Y.
2Heating X with zinc powder / A yellow solid Z was formed, which turned white on cooling. Metal Y was also formed.
(a) / Test 1 could be carried out using the set-up shown below.
(i) / Suggest ONE way to show that a metal was formed in this test.
(1 mark)
(ii) / Suggest why it was necessary to burn the residual hydrogen in the set-up.
(1 mark)
P.T.O.
Form 6 / Combined Science - Chemistry / P.6
4. / (b) / Suggest what solid X and Z might be.
(2 marks)
(c) / In test 2, predict what will be observed if silver solid is used instead of zinc powder.
(1 mark)
(d) / Predict whether metal Y or zinc was discovered earlier. Explain your answer.
(2 marks)
5. / The diagram below shown the set-up used in performing a microscale experiment. A few drops of 2M hydrochloric acid were added to the sodium sulphite powder and the dish was immediately covered with its lid. Sulphur dioxide gas formed by the reaction between sodium sulphite powder and hydrochloric acid eventually filled up the whole set-up.
(a) / Write an ionic equation, with state symbols, between the sodium sulphite powder and 2M hydrochloric acid.
(2 marks)
To be continued
Form 6 / Combined Science - Chemistry / P.7
5. / (b) / State the expected observations at position A and position B. In each case, write a relevant chemical equation if a reaction occurred.
(i) / Position A
(ii) / Position B
(4 marks)
(c) / Suggest one advantage of replacing test tube experiments with microscale experiments.
(1 mark)
6. / A student determines the molecular formula of a hydrocarbon W with the following set-up:
A known mass of W was heated in excess oxygen. The following results were obtained.
Mass of U-tube A before the experiment = 70.435 g
Mass of U-tube B before the experiment = 67.544 g
Mass of U-tube A after the experiment = 84.493 g
Mass of U-tube B after the experiment = 101.908 g
P.T.O.
Form 6 / Combined Science - Chemistry / P.86. / (a) / Determine the empirical formula of W.
(3 marks)
(b) / The relative molecular mass of W is 308.0. Calculate the molecular formula of W
(2 marks)
(c) / Consider the following series of reactions:
W + H2 Y 2C8H18 + 2A
(i) / State the type of reaction between compound W and H2to form compound Y.
(ii) / Name the process X
(iii) / Draw the structural formula of compound A.
(3 marks)
To be continued
Form 6 / Combined Science - Chemistry / P.97. / A part of the electrochemical series of metals and a chemical cell composed of zinc and metal X. is shown below:
(a) / (i) / In which direction will electrons flow in the external circuit of thecell? Explain.
(ii) / Write ionic half-equations for the reactions occurred at the zinc strip andthestrip made of metal X respectively.
(iii) / Explain which electrode is cathode.
(5 marks)
(b) / If the zinc strip and zinc sulphate solution arereplaced by a tin (Sn) strip and tin(II) chloride solution respectively, explain whatwouldbe the direction of the electron flow?
(1 mark)
(c) / State ONE function of salt bridge.
(1 mark)
END OF PAPER
BaptistLuiMingChoiSecondary School
F.6 Mock Examination (2012-13) / Suggested AnswersCombined Science - Chemistry
SECTION A (MULTIPLE-CHOICE QUESTIONS)
01 / 02 / 03 / 04 / 05 / 06 / 07 / 08 / 09 / 1000 / A / A / C / A / C / D / B / A / B / C
10 / B / C / B / D / D / A / C / B / C / D
20 / B / D / C / A
SECTION B (QUESTION-ANSWER BOOK)
1. / (a) / T: Fluorine / F ; X: Chlorine / Cl ; Z: Sodium / Na [1](b) / (i) / / [1] / (ii) / / [1]
(c) / Compound formed in (b)(ii) has a higher melting point. For compound formed in (b)(ii), large amount of energy is required to break the network of strong electrostatic attraction between oppositely charged ions/ ionic bond[1]while only a little amount of energy is required to break the weak intermolecular forces[1]between molecules of compound formed in (b)(i).
(d) / Lampost / Fireworks
(e) / The compound is made of ions. It conducts electricity in aqueous or molten state because the ions are mobile. [1] On the other hand, it does not conduct electricity in solid state because the ions are not mobile due to the attraction of strong ionic bonds. [1]
Y. / (a) / Na2SO3 (s) + 2H+ (aq) 2Na+ (aq) + SO2 (g) + H2O (l) [2]
(b) / (i) / SO2 (g) + Ca(OH)2 (aq) CaSO3 (s) + H2O (l) [1]
2. / (a) / FromThe lime water turns milky from colourless to pale pink.[1]
(b) / (ii) / 2NaOH + H2SO4 → Na2SO4 + H2O[1]2H2O (l) + 5SO2 (g) + 2MnO4- (aq) 4H+ (aq) + 2Mn2+ (aq) + 5SO42- (aq) [1]
(i) / Less chemicals are used / less harmful to environment / less dangerous / easy to handle / save money / save time [1] [1]
The potassium permanganate solution changes from purple to colourless. [1]
(c) / (ii) / No. of moles of NaOH / = 2 no. of moles of H2SO4 [1]
= 2 0.1 25.0 10-3
= 5.0 10-3 mol [1]
P.2
3. / (a) / It acts as a solvent or a catalyst. [1](b) / It is used to condense vapour formed from the mixture during heating, thus preventing the escape of vapour. [1]
Molarity of NH3 = = 0.248 M [1]
P.2
2 / (d) / Disagree. Sodium hydroxide reacts with carbon dioxide in air [1] and therefore the mass measured will not be accurate.(e) / Pipette25.00 cm3 of 1M dilute sulphuric acid into a 250 cm3volumetric flask[1].
Rinse the pipette by distilled water and transfer the washing to the volumetric flask. [1]
Add distilled water to the graduation mark of volumetric flask. [1]
Invert the volumetric flask several times to make a uniform solution.
Communication mark [1]
3. / (a) / heat released / = mc∆T [1]
= 100 × 4.18 × 3.5
= 1.463 kJ
amount of KOH used / = 0.500 ×0.025 / = 0.050mol
amount of KOH used / = 0.500 ×0.025 / = 0.050mol
∆H / = (1.463 / 0.025)
= −58.5 kJ mol–1 [1]
(b) / Temperature change will be smaller. [1]
Amount of base reacted would be the same / excess acid would not react /KOH is the limiting reagent [1]
Same energy released to larger mass of water [1]
(c) / . [1]
ΔH1
ΔH2
= / = ΔH2 + ΔH3[1]
= ΔH1 – ΔH3
= (–89.4) – (–58.5)
= –30.9 kJ mol–1[1]
4. / (a) / (i) / The solid obtained is a good conductor of electricity.[1]
(ii) / Hydrogen is explosive / flammable. [1]
(b) / X: copper oxide [1]
Y: zinc oxide[1]
(c) / No observable changes. [1]
(d) / Metal Y was discovered earlier.[1]
Zinc is more reactive than metal Y and hence more difficult to extract.[1]
P. / (ii) / No. of moles of NaOH / = 2 no. of moles of H2SO4 [1]
= 2 0.1 20.2 10-3
= 4.04 10-3 mol [1]
Molarity of NH3 = = 0.1616 M [1]
P.
P.3
5. / (a) / Na2SO3 (s) + 2H+ (aq) 2Na+ (aq) + SO2 (g) + H2O (l) [2](b) / (i) / SO2 (g) + Ca(OH)2 (aq) CaSO3 (s) + H2O (l) [1]
The lime water turns milky fromFrom colourless. to pale pink[1]
(ii) / 2H2O (l) + 5SO2 (g) + 2MnO4- (aq) 4H+ (aq) + 2Mn2+ (aq) + 5SO42- (aq) [1]
The potassium permanganate solution changes from purple to colourless. [1]2NaOH + H2SO4 → Na2SO4 + H2O[1]
(c) / Less chemicals are used / less harmful to environment / less dangerous / easy to handle / save money / save time [1]
6 / (a) /
(b) / Let (CH2)n be the molecular formula of W.
n(12.0 + 2 x 1.0)= 308.0[1]
n= 22
∴the molecular formula of W is C22H44.[1]
P.4
6. / (c) / (i) / Addition reaction [1]
(ii) / Cracking [1]
(iii) / [1]
7 / (a) / (i) / From zinc strip to metal X.[1]
It is because zinc loses electrons more readily than X.[1]
(ii) / At the zinc strip:
Zn(s) Zn2+(aq) + 2e–[1]
At the strip made of metal X:
X2+(aq) + 2e– X(s)[1]
(iii) / The strip made of metal X.
This is because reduction occurs at this strip.[1]
(b) / The direction of electron flow will be reversed. / Electrons will flow frommetal X to tin in the external circuit because tin is less readily to lose electrons than X according to the E.C.S. [1]
(c) / It completes the circuit by allowing ions to move from one half-cell to theother.[1]