Chemistry 9701/12 May/June 2021: question paper and mark scheme

Question

Which statement about the Avogadro constant is correct? A It is the mass of one mole of any element. B It is the mass of 6.02 × 1023 atoms of any element. C It is the number of atoms in one mole of neon. D It is the number of atoms in 12 g of any element.

Question

Which equation represents the first ionisation energy of iodine? A 1 2 I2(g) + e– → I–(g) B I(g) + e– → I–(g) C 1 2 I2(g) → I+(g) + e– D I(g) → I+(g) + e–

Question

The structures represent three compounds, each with four carbon atoms per molecule. X Y Z O O O OH O O–Na+ Which row is correct? lowest highest boiling point boiling point A X Y Z B Y X Z C Z X Y D Z Y X

Question

The structural formula of alliin is shown. alliin H H O NH2 y z xC C CH2 S CH2 C H H CO2H What are the approximate bond angles x, y and z in a molecule of alliin? x y z A 90° 90° 109° B 120° 109° 90° C 120° 120° 109° D 180° 109° 109°

Question

Flask Q contains 5 dm3 of helium at 12 kPa pressure. Flask R contains 10 dm3 of neon at 6 kPa pressure. If the flasks are connected at constant temperature, what is the final pressure? A 8 kPa B 9 kPa C 10 kPa D 11 kPa

Question

Sodium chloride, water and air represent three states of matter – solid, liquid and gas. Which row is correct? sodium chloride water air A particles held can easily be can easily be in rigid structure compressed compressed B particles stationary particles move cannot easily be compressed C particles stationary particles stationary particles move D resistant to cannot easily be can easily be change of shape compressed compressed

Question

The reaction pathway diagram for the catalysed reaction and the uncatalysed reaction between N2 and H2 is shown. N2(g) + 3H2(g) 2NH3(g) Which letter represents the activation energy for the first step in the decomposition of NH3 in the presence of a catalyst? A C B energy N2(g) + 3H2(g) D 2NH3(g) reaction pathway

Question

Nitrogen and oxygen can react together to form nitrogen monoxide, NO. N2 + O2 → 2NO ΔH = +180 kJ mol–1 What is the bond energy of the bond between the atoms in NO? A 630 kJ mol–1 B 810 kJ mol–1 C 1260 kJ mol–1 D 1620 kJ mol–1

Question

The equation for a redox reaction is shown. SnCl 2(aq) + 2HgCl 2(aq) → SnCl 4(aq) + Hg2Cl 2(s) Which species is being oxidised in this reaction? A Sn2+ B Cl – C Hg+ D Hg2+ 10 3.60 moles of hydrogen gas and 2.00 moles of iodine vapour are placed in a reaction vessel which is then sealed and maintained at a constant temperature. The equation for the reaction is shown. H2 + I2 2HI At equilibrium, 3.20 moles of hydrogen remain. All reactants and products are gaseous. What is the value of Kp under these conditions? A 0.0313 B 0.125 C 0.156 D 8.00

Question

In the question paper above.

Question

Two chemicals, X and Y, react together in solution to give product Z. The rate of formation of product Z at the start of the reaction was measured in five experiments, 1–5, using various concentrations of X and Y. The results are shown. experiment starting concentration starting concentration rate of formation of Z number of X / mol dm–3 of Y / mol dm–3 at the start / mol dm–3 s–1 1 0.10 0.10 0.0001 2 0.10 0.20 0.0004 3 0.10 0.40 0.0016 4 0.20 0.10 0.0001 5 0.40 0.10 0.0001 Which statement is correct? A The rate of the reaction is directly proportional to the concentration of reagent X. B The rate of the reaction is directly proportional to the concentration of reagent Y. C The rate of the reaction is not affected by the concentration of reagent X. D The rate of the reaction is not affected by the concentration of reagent Y.

Question

A sample of SiCl 4 is added to cold water. Which statement describes the mixture formed at the end of the reaction? A acidic solution with no precipitate B acidic solution with white precipitate C neutral solution with no precipitate D neutral solution with white precipitate

Question

L and M are elements in Period 3 of the Periodic Table. ● The oxide of L is a solid at room temperature. This oxide has a giant structure. ● The chloride of L does not react with water. ● Argon is the only element in Period 3 with a lower melting point than M. Which formula represents a compound of elements L and M? A Al 2S3 B MgS C NaCl D PCl 5

Question

A farmer requires a solid compound to raise the pH of the soil in a field from 5.5 to above 6.0. Which compound could the farmer use? A (NH4)2SO4 B NH4NO3 C Ca(OH)2 D Ca(NO3)2

Question

Z is an anhydrous compound of a Group 2 element. When it is heated, Z undergoes thermal decomposition to produce two different gases. Z has relatively low thermal stability compared to other Group 2 compounds containing the same anion as Z. What is compound Z? A barium carbonate B barium nitrate C magnesium carbonate D magnesium nitrate

Question

Which row gives mixtures that both result in the oxidation of a halide ion? mixture 1 mixture 2 A AgNO3(aq) and NaCl (aq) concentrated H2SO4(aq) and HI(aq) B Br2(aq) and NaCl (aq) concentrated H2SO4(aq) and HCl (aq) C Cl 2(aq) and NaBr(aq) CH3CHBrCH3(l) + NaOH (ethanolic) D Br2(aq) and NaI(aq) concentrated H2SO4(aq) and NaBr(s)

Question

Chlorine gas is widely used to treat contaminated water. When chlorine is added to water, which chemical species present is responsible for killing bacteria? A Cl O2– B Cl – C HCl D Cl O–

Question

What is an environmental consequence of the uncontrolled use of nitrate fertilisers? A acid rain B low oxygen levels in streams C ozone depletion D the greenhouse effect

Question

Ammonia gas, NH3, and hydrogen sulfide gas, H2S, react together to form the salt ammonium sulfide, (NH4)2S. Ammonium sulfide dissolves in water to produce an orange alkaline solution. (NH4)2S(aq) NH3(aq) + NH4SH(aq) The addition of NaOH(aq) to this solution produces a gas, X. The addition of HCl (aq) to a separate portion of this solution produces a gas, Y. X and Y could represent different gases or identical gases. What are the identities of X and Y? X Y A H2S H2S B H2S NH3 C NH3 H2S D NH3 NH3

Question

Compound P is treated with an excess of hydrogen gas in the presence of a nickel catalyst. The product Q is fully saturated. compound P What is the number of chiral carbon atoms in the product Q? A 4 B 5 C 6 D 7

Question

Hexadeca-10,12-dien-1-ol is produced by silk moths from hexadecanoic acid in a three-step enzymic process. hexadecanoic acid O OH step 1 O OH step 2 O OH step 3 OH Which row contains correct descriptions of the three steps? step 1 step 2 step 3 A elimination elimination dehydration B elimination reduction reduction C oxidation elimination oxidation D oxidation oxidation reduction

Question

Compound X can be converted into compound Y in a single step. compound Y OH X O O What could be the identity of X? A B C D

Question

Methane and bromine react by free radical substitution. P and Q are involved in the reaction mechanism. P and Q: ● are both involved in propagation steps as reactants ● are both involved in termination steps as reactants. What could be P and Q? A Br and H B Br and CH3 C Br and C2H6 D CH3 and CH3Br

Question

A few drops of 2-bromopropane were placed in a test-tube. An equal volume of aqueous silver nitrate was added. A precipitate was formed. The experiment was repeated with 2-iodopropane. Which row is correct? colour of precipitate from faster rate of reaction 2-bromopropane + AgNO3(aq) A cream 2-bromopropane + AgNO3(aq) B yellow 2-bromopropane + AgNO3(aq) C cream 2-iodopropane + AgNO3(aq) D yellow 2-iodopropane + AgNO3(aq)

Question

Sodium methoxide, Na+CH3O–, reacts with 2-chloro-2-methylpropane in a nucleophilic substitution reaction. The nucleophile is the CH3O– ion. Which row is correct? intermediate or product transition state A (CH3)3C+ (CH3)3COCH3 B (CH3)3C+ (CH3)3CCH2OH – H 3C CH3 C H3CO C Cl HOCH2C(CH3)3 CH3 – H 3C CH3 D H3CO C Cl H3COC(CH3)3 CH3

Question

Alcohol X reacts with concentrated sulfuric acid to produce a mixture of products. Two of the products are structural isomers of each other. What could be X? A hexan-2-ol B pentan-1-ol C pentan-3-ol D propan-2-ol

Question

Which reaction will form a strong organic base? A ethanol and acidified sodium dichromate B ethanol and hot aluminium oxide C ethanol and sodium D ethanol and hydrogen chloride

Question

Which reaction mechanism for the formation of C2H5CH(OH)(CN) is correct? H+ O– OH G– O H H A G+ C C N C– H N N H+ O– OH G– O H H B G+ C C N C– H N N H+ O– OH G+ O H H C G– C C N C– H N N H+ O– OH G– O H H D G+ C C N C– H N N

Question

The synthesis shown may be used for the production of propan-1-ol. step 1 step 2 compound X OH N Which row gives the correct reagents for steps 1 and 2? step 1 step 2 A HCl (aq) H2 + Ni B HCl (aq) LiAl H4 C NaOH(aq) H2 + Ni D NaOH(aq) NaBH4

Question

The molecular formula of Z is C4H8O. The infra-red spectrum of Z is shown. 100 transmittance / % 50 0 4000 3000 2000 1500 1000 500 wavenumber / cm–1 What could be Z? A B C D OH O O OH OH Section B For each of the questions in this section, one or more of the three numbered statements 1 to 3 may be correct. Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against the statements that 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 1 and 2 2 and 3 1 only are only are only are is correct correct correct correct No other combination of statements is used as a correct response. Use of the Data Booklet may be appropriate for some questions.

Question

In which ions are the number of electrons equal to the number of neutrons? 19 − 1 9F 2 31 15 P− 23 + 3 11Na

Question

Compound X is a straight chain hydrocarbon with an Mr of 84. What can be determined about X? 1 empirical formula 2 molecular formula 3 whether X contains a C=C bond or not The responses A to D should be selected on the basis of A B C D 1, 2 and 3 1 and 2 2 and 3 1 only are only are only are is correct correct correct correct No other combination of statements is used as a correct response.

Question

When a sample of ammonium chloride is warmed it decomposes into ammonia and hydrogen chloride gas. NH4Cl (s) → NH3(g) + HCl (g) reaction 1 cold surface solid ammonium chloride (reformed) solid ammonium chloride heat When the mixture of hot ammonia and hydrogen chloride gases hit a cold surface, a white solid of ammonium chloride reforms. Which statements are correct? 1 Reaction 1 is in dynamic equilibrium. 2 Reaction 1 is reversible. 3 Reaction 1 is an endothermic reaction.

Question

Hydrogen chloride gas is formed by the reaction shown. H2(g) + Cl 2(g) → 2HCl (g) What will change the average kinetic energy of the reacting gas particles? 1 increasing the temperature and increasing the concentration of hydrogen 2 cooling the reaction mixture and adding a catalyst 3 adding a catalyst and increasing the concentration of chlorine

Question

Which oxides will cause a change in pH when added to water? 1 CaO 2 Al 2O3 3 SiO2

Question

Which reaction routes can be used to make a pure sample of barium sulfate? heat dilute dilute filter, wash 1 Ba product product product in O2 HCl H2SO4 and dry strong solid an excess dilute filter, wash 2 Ba(NO3)2 product product heat in air product of water H2SO4 and dry dilute dilute filter, wash 3 Ba(OH)2 product product HNO3 H2SO4 and dry

Question

Cortisone is a synthetic hormone. cortisone O OH HO OH H H H O Which classes of alcohol does this molecule contain? 1 primary alcohol 2 secondary alcohol 3 tertiary alcohol

Question

Which changes are commonly involved in the formation of an addition polymer? 1 the formation of a σ-bond 2 the breaking of a π-bond 3 the change in hybridisation of the orbitals of a carbon atom from sp2 to sp3 The responses A to D should be selected on the basis of A B C D 1, 2 and 3 1 and 2 2 and 3 1 only are only are only are is correct correct correct correct No other combination of statements is used as a correct response.

Question

Which alcohols can be oxidised to form an organic compound which will give coloured precipitates with both 2,4-dinitrophenylhydrazine reagent and alkaline aqueous iodine? OH 1 OH O 2 3 OH

Question

Which mixtures form a carboxylic acid as one of the products? O 1 O + H2SO4(aq) o O– 2 O + H2SO4(aq) o O 3 + H2SO4(aq) o