Tpjc h2chem Prelim p1 2009

TPJC Prelim Exam 09 H2 Chem/ P1

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TPJC PRELIMINARY EXAM 2009 H2 CHEMISTRY PAPER 1 Section A : For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 Aqueous acidified potassium manganate (VII) is used to oxidize ethanedioate

ions, C2O42- , to CO2. In the complete oxidation reaction, it was found that the

mole ratio of MnO4- ions to C2O4

2- ions is 2:5. What concentration of 30cm3 aqueous acidified potassium manganate (VII) is required to oxidize completely 0.05 mol of the salt KHC2O4.H2C2O4?

A 0.53 moldm-3 C 2.53 moldm-3

B 1.33 moldm-3 D 2.85 moldm-3 2 Disproportionation reaction occurs when an element undergoes oxidation and

reduction simultaneously. Which of the following equations describes a disproportionation reaction?

A 3ClO- ClO3- + 2Cl-

B 2H2C2O4 2H2O + 2C + 2CO + 2O2

C 2FeSO4 Fe2O3 + SO2 + SO3

D 2KMnO4 MnO2 + MnO + K2O + 2O2

3. Hydrogen peroxide reacts with iodide ions in acidic solution as follows:

H2O2(aq) + 2H+ (aq) + 2I- (aq) 2H2O (l) + I2 (aq)

The proposed mechanism for the above reaction is:

H2O2 + I- H2O + IO- (slow)

H+ + IO- HIO (fast)

HIO + H+ + I- H2O + I2 (fast)

Which of the following rate equations for the overall reaction is consistent with the kinetics of the proposed mechanism?

A Rate = k[H2O2] [I-]

B Rate = k[ H2O2] [H+]2 [I-]2

C Rate = k[H2O2]2 [H+] [I-]

D Rate = k[H2O2]2[HIO]


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4 Which one of the following statement best explains the reason why the 1st

ionisation energy of sulphur is lower than that of phosphorus?

A The sulphur atom is larger in size than the phosphorus atom.

B Sulphur anion is more readily formed compared to that of phosphorus.

C The electron which is to be lost is paired with another electron.

D It is more difficult for the phosphorus atom to lose an electron than the sulphur atom.

5 What type of intermolecular forces is present in liquid tetrachloromethane.

CCl4?

A Co-ordinate bonding

B Induced dipole – induced dipole interactions

C Permanent dipole – permanent dipole interactions

D Covalent bonding 6 A fixed mass of an ideal gas occupies a vessel of volume V at a pressure P.

which of the following graph correctly shows the relationship between product PV and P? (Assuming gas is at constant temperature).

A

B

C

D


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7 Deuterium (2H) and Tritium (3H) are isotopes of hydrogen. Given that a 3g sample of hydrogen at temperature T and volume V exerts a pressure p, which of the following would also exert a pressure p at the same temperature T?

A 3g of deuterium of volume V

B 5g of tritium of volume V/3

C A mixture of 1g of deuterium and 1g of tritium of total volume V

D A mixture of 4g of deuterium and 3g of tritium of total volume V 8 Which of the following equation correctly defines the enthalpy change of

formation of a compound?

A 2H2 (g) + 2O2 (g) 2H2O2 (l)

B N2H4 (l) + O2 (g) N2 (g) + 2H2O (g)

C CO (g)+ ½ O2 (g) CO2(g)

D Na(g) + Cl(g) NaCl (g) 9 The circuit shown in the diagram was set up.

Which reactions will occur at the electrodes?

Anode reaction Cathode reaction

A Oxygen gas is evolved. Hydrogen gas is evolved.

B Silver dissolves preferentially. Hydrogen gas is evolved.

C Iron dissolves preferentially. Hydrogen gas is evolved.

D Silver and iron both dissolve. Silver sulphate ppt formed.


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10 Solid sodium iodide is slowly added to a solution that contains 0.015 moldm-3 of both copper (I) and silver ions. Given that the Ksp of copper (I) iodide is 5.1 x 10-12mol2dm-6 and Ksp of silver iodide is 8.3 x 10 -17mol2dm-6, calculate the concentration of I- ions when silver (I) iodide just begins to precipitate.

A 1.63 x 10-14 moldm-3

B 2.44 x 10-15 moldm-3

C 5.53 x 10-15 moldm-3

D 3.36 x 10-16 moldm-3

11 30.0 cm3 of 2.4 moldm-3 ethanoic acid (Ka =1.8 x 10-5 moldm-3) is added to

90.0 cm3 of 0.8 moldm-3 sodium hydroxide. The pH of the resulting mixture is

A 2.35 B 8.99 C 9.07 D 9.26

12 The experimental results obtained for the reaction between X and Y (carried out at 25 °C) are given in the table below. What is the rate equation for this reaction given that original concentration of X is 1.0 mol dm−3 and Y is 2.0 mol dm−3 respectively.

Expt Volume of X

/cm3

Volume of

Y /cm3

Initial rate of reaction

/mol dm−3 min−1

1 20 20 1.00

2 20 30 1.20

3 10 30 1.50

A Rate = k [X] [Y]

B Rate = k [X] [Y]2

C Rate = k [X]2 [Y]

D Rate = k [X]0 [Y]1


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13 The following graphs show how three properties of the elements, Na to P, and their compounds, vary with proton number.

Graph 1 Graph 2 Graph 3

What properties are shown by the three graphs?

Graph 1 Graph 2 Graph 3

A Melting point of oxide Melting point of chloride Conductivity of element

B Melting point of oxide Melting point of element Melting point of chloride

C Melting point of chloride Conductivity of element Melting point of oxide

D Melting point of chloride Melting point of element Melting point of oxide 14 For which one of the following metal complexes is the electronic configuration

wrong?

Complex Electronic configuration of central metal ion

A [Zn(NH3)4]2+ [Ar] 3d10

B [Co(H2O)6]3+ [Ar] 3d6

C [Cu(NH3) 4]2+ [Ar] 3d10

D [Ni(CN)6]4- [Ar] 3d8

11 12 13 14 15 proton number




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15 How do the following properties of Group II elements vary down the group?

(i) the standard electrode potential of EM

2+/ M

(ii) the first ionisation energy, 1st I.E. (iii) the electronegativity

EM

2+/ M 1st I.E. Electronegativity

A more negative decreases decreases

B less negative decreases increases

C more negative increases decreases

D more negative increases increases 16 Magnesium iodates(V) undergoes thermal decomposition to yield products as

shown by the equation below. The other Group II iodates(V) also undergo similar thermal decomposition.

2Mg(IO3)2(s) 2MgO(s) + 2I2(g) + 5O2(g)

The three graphs given below show the change in mass when 2.00 g each of

three Group II iodates(V) were heated separately at a temperature T oC.

Which three Group II iodates(V) give rise to these graphs? Graph (1) Graph (2) Graph (3)

A Ca(IO3)2 Mg(IO3)2 Ba(IO3)2

B Mg(IO3)2 Ca(IO3)2 Sr(IO3)2

C Sr(IO3)2 Ba(IO3)2 Ca(IO3)2

D Ca(IO3)2 Ba(IO3)2 Sr(IO3)2


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17 X2, Y2 and Z2 are Cl2, Br2 and I2 but are not necessarily in the given order. The table below shows the results of experiments involving the addition of these

halogens to separate aqueous solutions containing the halide ions followed by the addition of an organic solvent.

Experiment Reactants Observation after addition of CCl4 and the mixture shaken

1 X2(aq) + Y–(aq) violet organic layer

2 Z2(aq) + X–(aq) violet organic layer

3 Y2(aq) + Z–(aq) reddish brown organic layer

4 Z2(aq) + Y–(aq) reddish brown organic layer

Which of the following statements is correct? A X– is less reducing than Y–. B Y2 is a stronger oxidising agent than Z2. C When X2(aq) is added to Z–(aq), followed by addition of CCl4, a violet

organic layer is obtained. D X2 is the strongest oxidising agent.

18 Molecule Y contains only carbon, hydrogen and a single oxygen atom.

If Y is a aldehyde, what is the smallest number of carbon atoms needed for it to be chiral?

A 4 C 6

B 5 D 9

19 Which of the compounds exhibit cis-trans isomerism?

1

2

3

4

A All of the above C All except 2

B Only 1 and 3 D Only 2 and 4


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20 In the free radical substitution reaction of ethane with chlorine, the following energy diagram for a single reaction step is obtained.

To which of the following steps does this diagram apply?

A Cl2 2Cl ·

B CH3 ·+ Cl · CH3Cl

C CH3CH3 2CH3 ·

D CH3 ·+ Cl2 CH3Cl + Cl ·

21 Which of the following best explains why a high yield of 2-bromobutane is not

usually obtained in the reaction of butane and bromine?

A Bromine reacts with butane too vigorously.

B Bromine is able to replace any of the hydrogen atom in butane.

C The central 2- and 3- carbon atoms of butane are too strongly electrophilic.

D The central 2- and 3- carbon atoms of butane are too strongly nucleophilic.

22 Propene reacts with hydrogen chloride to form chloropropane. Which of the

following best describes the intermediate ?

A It is a complex which contains hydrogen, carbon and chlorine.

B It is not a free radical.

C It has a negative charge.

D It is an electrophile.

TPJC Prelim Exam 09 H2 Chem/ P1 10

23 Which of the following compound is the main product formed when X is refluxed with excess potassium hydroxide?

X A B C D 24 Which of the following compound will decolourise reddish-brown colour of

bromine?

A B C D


25 By heating X in a sealed tube with ammonia, a primary amine can be obtained. The same primary amine can also be prepared by reduction of Y. Which pair of X and Y would give the same primary amine?

X Y

A Cl2CHCH2Cl HOCH2CH2CN

B C6H5CH2CH2Br C6H5CH2CH2CN

C (CH3)2CHCH2CH2Cl CH3CH2CH2CH2CN

D HOCH2C(CH3)2CH2Br HOCH2C(CH3)2CN 26 Which reagent gives the same observations with butanal and with butan-2-ol?

A 2,4-DNPH C Acidified KMnO4

B Fehling’s solution D Tollen’s reagent 27 Which of the following reagents would react with hydrogen cyanide to give a

organic compound with a chiral centre?

A (CH3)2CHCO2CH3 C CH3COCH3

B (CH3)2CHCHO D (CH3)2CHCH2CH3 28 Which of the following sequence correctly shows the value of pKa increasing

continuously?

A CH3COOH < C6H5OH < C6H5CH2CH2OH

B C6H5CH2CH2OH < C6H5OH < CH3COOH

C ClCH2CH2OH < C6H5OH < Cl3CCOOH

D Cl3CCOOH < C6H5OH < CH3COOH 29 Which of the following statement best explains why proteins are able to

function as pH buffers?

A Proteins are made up of amino acids with oppositely charged R-groups.

B Proteins are made up of primary, secondary and tertiary structures.

C Proteins usually have a high molecular mass.

D Proteins contain both carboxylic acids and amino groups.


30 Compound Z gives white fumes with PCl5 , and releases ammonia gas upon addition of hot NaOH. Which of the following compound could be Z?

A (CH3)2CHCO2CH2NH2 C CH3CH2CONH2

B HOCH2CH2COCH2NH2 D HOCH2CH2CONH2 Section B : For each of the questions in this part, one or more of the three numbered statements 1 to 3 may be correct.

Decide whether each of the statements is or not correct (you may find it helpful to put a tick against the statements which you consider to be correct).

The responses A to D should be selected on the basis of

A B C D 1, 2 and 3 are

correct 1 and 2 only are correct

2 and 3 only are correct

1 only is correct

No other combination of statements is used as a correct response. 31 Which of the following are correct statements about the s, p and d orbitals of

principal quantum numbers 1, 2 and 3.

1 Each orbital (s, p and d) can contain maximum two electrons with opposite spins.

2 A series of transition elements arises from the filling of incomplete p and d orbitals 3 Within the same principal quantum number, the s orbital has a higher

energy than the p orbital. 32 The use of the Data Booklet is relevant to this question. Water dissociates as follows: H2O H+ (aq) + OH- (aq) ∆H = +57.2 kJ mol-1 at 298K

Which of the following is true? 1 Concentration of H+ (aq) increases as temperature increases. 2 At lower temperatures, concentration of OH- decreases. 3 Water is more acidic at higher temperatures.


33 The diagram shows the energy profile of a reaction where:

reactants products where kf denotes rate constant of forward reaction kb denotes rate constant of backward reaction

Which of the following is correct? 1 Both rate constants kf , kb will increase in the presence of a catalyst. 2 Rate constant kf will increase when concentrations of reactants is

increased. 3 Since reaction is endothermic, heating the equilibrium mixture will

increase kf , but decrease kb.

34 The graphs below show the progress of the reaction between NaOH and a compound X. What deductions can be made from these results?

1 Rate = k [NaOH] [X] 2 Rate of reaction is directly proportional to [NaOH] 3 Rate is independent of [X]

kf

kb

Graph A: [NaOH] = 1 moldm-3

Graph B: [NaOH] = 2 moldm-3


35 Which of the following statements is true about the elements in Period 3 of the

Periodic Table? 1 Melting points generally decrease across the period.

2 First ionisation energies generally increase across the period.

3 The chlorides of the elements change from ionic to covalent across the period.

36 The use of the Data Booklet is relevant to this question.

The colours of various vanadium ions in aqueous solution are given in the table

below.

Oxidation state V IV III II

Ion VO2+ VO2+ V3+ V2+

Colour yellow blue green violet

Which of the following reactions (if any) can produce a green solution?

1 Adding excess Sn4+ ions to an acidified solution containing V2+ ions. 2 Bubbling excess SO2 into an acidified solution of VO2

+ ions. 3 Adding K2S2O8 to an acidified solution containing VO2

+ ions. 37 Daminozide (structure shown) is a plant growth regulator. It is usually sprayed

on fruit to regulate their growth, to increase their harvest, and to enhance their colour.

Which of the following are correct about Daminozide?

1 It is able to form a zwitterion. 2 It reacts with hot NaOH to give a sodium salt of a dicarboxylic acid 3 It is optically active


38 Which compounds can be obtained from butan-2-ol, by reacting it with concentrated sulphuric acid under different conditions?

1 CH2=CHCH2CH3 2 CH3CH=CHCH3 3 CH3CHHSO4CH2CH3

39 Which of the following can be deduced from Compound X (structure shown

below)?

Compound X

1 It is optically active. 2 It gives yellow ppt with iodoform test. 3 Upon heating with alcoholic KOH, it gives a product that exhibits

stereoisomerism.

40 Which of the following reacts completely with 1 mol of compound Z (structure

shown)? Compound Z

1 4 mol of Na 2 4 mol of PCl5 3 4 mol of NaOH

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Tpjc h2chem Prelim p1 2009