Chemistry 9701/12 October/November 2020: question paper and mark scheme

Question

What is the average oxidation number of sulfur in each compound? Ca(HSO3)2 Na2S2O3 A 4 2 B 4 4 C 6 2 D 6 4

Question

An ore of manganese contains 4% by mass of MnO2 and no other manganese compound. Which mass of manganese would be obtained from 1 tonne of this ore? A 25.3 kg B 40.0 kg C 63.3 kg D 632 kg

Question

Which atomic orbitals are occupied in an atom of phosphorus? A 1p 2s 2p B 2s 2p 2d C 2s 2p 3s D 2p 3s 3d

Question

The structure of compound A is shown. compound A CH3 CH3 CH CH C CH C CH CH2OH CH3 CH3 Some of the carbon atoms in compound A have a tetrahedral arrangement of bonds. Some of the carbon atoms in compound A have a trigonal planar arrangement of bonds. How many carbon atoms are there of each type? tetrahedral trigonal planar A 5 12 B 8 8 C 9 6 D 9 8

Question

A white powder is known to be a mixture of magnesium oxide and aluminium oxide. 100 cm3 of 2 mol dm–3 NaOH(aq) is just enough to dissolve the aluminium oxide in x grams of the mixture. The reaction is shown. Al 2O3 + 2OH– + 3H2O → 2Al (OH)4– 800 cm3 of 2 mol dm–3 HCl (aq) is just enough to dissolve all of the oxide in x grams of the mixture. The reactions are shown. Al 2O3 + 6H+ → 2Al 3+ + 3H2O MgO + 2H+ → Mg2+ + H2O How many moles of each oxide are present in x grams of the mixture? aluminium magnesium oxide oxide A 0.05 0.25 B 0.05 0.50 C 0.10 0.25 D 0.10 0.50

Question

A graph of pV against T is shown for a fixed mass of gas. (p = pressure, V = volume and T = temperature in K.) pV T Which gas gives this graph over the widest range of temperatures and pressures? A hydrogen, H2 B hydrogen chloride, HCl C hydrogen fluoride, HF D oxygen, O2

Question

A weather balloon is filled with 12.0 kg helium. The weather balloon reaches a height of 20 km, the pressure inside the balloon is 6000 Pa and the temperature is 216 K. What is the volume of the weather balloon at this height, correct to three significant figures? A 897 dm3 B 1790 dm3 C 897 000 dm3 D 1 790 000 dm3

Question

Which pair of enthalpy changes will always share the same sign (i.e. both are always exothermic or both are always endothermic)? A enthalpy change of atomisation and enthalpy change of neutralisation B enthalpy change of atomisation and enthalpy change of solution C enthalpy change of combustion and enthalpy change of hydration D enthalpy change of solution and enthalpy change of hydration

Question

Chlorine dioxide, Cl O2, reacts with sodium hydroxide in the reaction shown. 2Cl O2 + 2OH– → Cl O2– + Cl O3– + H2O Which statement correctly describes this redox reaction? A Chlorine atoms are oxidised and oxygen atoms are reduced. B Chlorine atoms are reduced and oxygen atoms are oxidised. C Some chlorine atoms are oxidised and some chlorine atoms are reduced. D Some oxygen atoms are oxidised and some oxygen atoms are reduced.

Question

Sulfur dioxide and oxygen react to form sulfur trioxide. The reaction is reversible. 2SO2(g) + O2(g) 2SO3(g) Kp = 2.96 × 10–9 Pa–1 at 700 °C The reaction is allowed to reach equilibrium at 700 °C. The partial pressure of O2(g) is 375 kPa and the partial pressure of SO3(g) is 20.3 kPa. What is the partial pressure of SO2(g)? A 19.3 kPa B 609 kPa C 18 300 kPa D 609 000 kPa

Question

Ammonia is made by the Haber process. The reactants are nitrogen and hydrogen. N2(g) + 3H2(g) 2NH3(g) ∆H is negative What will increase the rate of the forward reaction? A adding argon to the mixture but keeping the total volume constant B decreasing the temperature C increasing the total pressure by reducing the total volume at constant temperature D removing ammonia as it is made but keeping the total volume of the mixture the same

Question

Element X, in Period 3, has the following properties. ● Its oxide has a giant structure. ● It forms covalent bonds with chlorine. ● Its oxide will neutralise HCl (aq). What is element X? A Mg B Al C Si D P

Question

Which row could refer to barium metal and barium hydroxide? colour seen pH of a saturated when the metal solution of is burnt in O2 the hydroxide A green flame 8 B green flame 13 C white flame 8 D white flame 13

Question

AgNO3(aq) is added to a solution of a halide ion, X–(aq), and aqueous ammonia is then added. The ionic equations for the two reactions that occur are shown. Ag+(aq) + X–(aq) AgX(s) equilibrium 1 Ag+(aq) + 2NH3(aq) Ag(NH3)2+(aq) equilibrium 2 Which statement is correct? A The position of equilibrium 1 lies to the left when X– = I–. B Increasing the concentration of ammonia causes the position of equilibrium 1 to move to the left. C Kc for equilibrium 2 is larger when X– = Cl – than when X– = I–. D Equilibrium 2 is a redox reaction.

Question

Water and ammonia take part in a reaction that produces the ammonium ion. Which statement about this reaction is correct? A The ammonia molecule and the ammonium ion do not have dipole moments. B The bond angle changes from 109.5° in the ammonia molecule to 107° in the ammonium ion. C The reaction is a redox reaction. D The water is acting as an acid.

Question

Due to their similar ionic radii, the reactions of lithium and magnesium and their corresponding compounds are very similar. Which statement about the reactions of lithium or its compounds can be predicted from this statement? A Lithium burns very slowly in oxygen. B Lithium carbonate decomposes on heating in a blue Bunsen burner flame, forming lithium oxide and carbon dioxide. C Lithium nitrate decomposes on heating, forming lithium nitrite, LiNO2, and oxygen. D Lithium reacts very violently with cold water, producing hydrogen.

Question

Which statement about Group 17 elements and their compounds is correct? A Chlorine reacts with cold concentrated sodium hydroxide to form NaCl and NaCl O3. B HCl is more thermally stable than HBr because chlorine is less electronegative than bromine. C Iodide ions are oxidised to iodine by concentrated sulfuric acid. D Silver iodide is soluble in dilute aqueous ammonia.

Question

Which substance, when warmed with aqueous ammonium chloride, would produce an alkaline gas? A CH3CO2H B CH3CH2OH C CH3CO2CH3 D CH3CH2ONa

Question

Compound X is the oxide of a Period 3 element. Compound X reacts with water to give an acidic solution. A solution is prepared by reacting 0.100 g of compound X with an excess of water. This solution is neutralised by exactly 25.0 cm3 of 0.100 mol dm–3 sodium hydroxide solution. What could be the identity of compound X? A Al 2O3 B MgO C P4O10 D SO3

Question

The unsaturated hydrocarbon octa-1,3,5,7-tetraene, C8H10, can display geometric isomerism. octa-1,3,5,7-tetraene CH2=CHCH=CHCH=CHCH=CH2 How many isomers exist? A 2 B 3 C 4 D 8

Question

What is the correct name for the compound shown? HO A 1,2,2-trimethylbutan-3-ol B 2-ethyl-2-methylbutan-2-ol C 3,3-dimethylpentan-2-ol D 4-hydroxy-3,3-dimethylpentane

Question

A polymer has the following repeat unit. It is made from two different monomers. CH2 CHCl CH2 CH CH CH2 Which pair of monomers could be used to make this polymer? A CH2=CHCl and CH2=CH2 B CH2=CHCl and CH2=CH–CH=CH2 C CH3–CH2Cl and CH3–CH=CH–CH3 D CH3–CH=CH–CH3 and CH2=CHCl

Question

Compound X contains two functional groups. compound X O CH3 C CHO Which reagent will react with only one of the functional groups? A acidified potassium dichromate(VI) B 2,4-DNPH reagent C hydrogen cyanide D NaBH4

Question

Ethanol can be converted into ethene in a single reaction. Ethanol can be converted into bromoethane in a single reaction. Under standard laboratory conditions, is a catalyst used in these reactions? ethanol to ethene ethanol to bromoethane A yes yes B yes no C no yes D no no

Question

Diols in which both hydroxy groups are bonded to the same carbon atom can spontaneously eliminate a molecule of water to produce a carbonyl compound. Which compound, after complete hydrolysis, gives a silver mirror with Tollens’ reagent? A 1,1-dibromobutane B 1,2-dibromobutane C 1,3-dibromobutane D 2,2-dibromobutane

Question

Which alcohol will give a yellow precipitate when warmed with alkaline aqueous iodine? A (CH3)2CHCH2OH B (CH3)3COH C CH3CH2C(OH)(CH3)2 D CH3CH(OH)CH2CH3

Question

How many structural isomers are there of molecular formula C5H10O that give a red precipitate with Fehling’s solution? A 1 B 2 C 3 D 4

Question

Which statement about the use of alkane fuels in internal combustion engines is correct? A C8H18 is used as fuel in internal combustion engines and reacts with oxygen and nitrogen from the air. B In limited oxygen, CO is produced which oxidises SO2 to SO3 in the atmosphere. C The catalytic converter removes polluting gases including NO2 and CO2. D Unburnt hydrocarbons and NO2 can react in sunlight to produce photochemical smog.

Question

Compound Z is shown. compound Z HO CO2H O HO O OH What is produced in good yield when compound Z is treated with an excess of sodium carbonate solution at room temperature? A B HO CO2Na NaO CO2Na O O HO O NaO O OH ONa C D NaO CO2H HO CO2Na O O + NaO O HO OH HO ONa OH

Question

The infra-red spectrum shown was obtained from compound G. 100 transmittance /% 50 0 4000 3000 2000 1500 1000 500 –1 wavenumber / cm What could be compound G? A CH3COCH2OH B CH3CH2CO2H C CH3CO2CH3 D CH3CHCHCH3 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. 3−

Question

The symbol for a phosphorus ion is 33 15 P . + The symbol for a potassium ion is 37 19 K . What do these two ions have in common? 1 the same number of electrons 2 the same number of neutrons 3 the same number of protons

Question

The repeat unit of a polymer is shown. H CN C C H CO2C2H5 n Which types of intermolecular forces exist in the solid polymer? 1 temporary dipole – induced dipole interactions 2 permanent dipole – permanent dipole interactions 3 hydrogen bonds 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

The diagram illustrates the enthalpy changes of a set of reactions. ∆H = –134 kJ mol–1 R S ∆H = +92 kJ mol–1 ∆H = –75 kJ mol–1 T U Which statements are correct? 1 The enthalpy change for the transformation U → R is + 42 kJ mol–1. 2 The enthalpy change for the transformation T → S is endothermic. 3 The enthalpy change for the transformation R → T is – 33 kJ mol–1.

Question

Which statements about a reaction that has reached dynamic equilibrium are correct? 1 The rate of the forward reaction equals the rate of the reverse reaction. 2 There is no overall change in the concentrations of reactants and products. 3 There is no change in the measurable properties of the system.

Question

Group 2 elements and their compounds show trends in their physical and chemical properties. Barium is above radium in Group 2 of the Periodic Table. Which statements are likely to be correct? 1 Barium hydroxide is less soluble than radium hydroxide. 2 Barium reacts less vigorously with water than radium does. 3 Barium sulfate is more soluble than radium sulfate.

Question

Which statements are correct? 1 The empirical formula of silicon(IV) oxide is SiO2. 2 The molecular formula of phosphorus(V) oxide is P2O5. 3 Silicon(IV) oxide and phosphorus(V) oxide are both simple molecular compounds.

Question

Which reagents could be used, under suitable conditions, to oxidise CH3CH2CH2OH to CH3CH2CHO? 1 acidified potassium manganate(VII) 2 acidified potassium dichromate(VI) 3 Tollens’ reagent

Question

Which free radicals can be generated during a free-radical substitution reaction between chlorine and ethane? 1 CH3• 2 CH2Cl CH2• 3 CH3CCl 2•

Question

Which substances have molecular formula C4H8O? 1 O 2 O OH 3

Question

Which reactions produce pentanoic acid? 1 CH3CH2CH2CH(OH)CH3 + H+ / MnO4–(aq) 2 CH3OCO(CH2)3CH3 + HCl (aq) 3 CH3(CH2)3CN + H2SO4(aq)