Chemistry 9701/13 May/June 2022: question paper and mark scheme

Question

Which atom has exactly three unpaired electrons in the ground state? A an isolated gaseous aluminium atom B an isolated gaseous carbon atom C an isolated gaseous chromium atom D an isolated gaseous phosphorus atom

Question

Which element has the second smallest atomic radius in its group and the second highest electrical conductivity in its period? A boron B calcium C magnesium D sodium

Question

Analysis of the hormone thyroxine gives the results shown. Heating 0.500 g of thyroxine with aqueous silver nitrate produces 0.604 g of silver iodide. All of the iodine in the thyroxine sample is converted to silver iodide. Complete combustion of 0.500 g of thyroxine produces 232 cm3 of carbon dioxide and 7.72 cm3 of nitrogen, measured under room conditions. Which molecular formula of thyroxine agrees with these values? A C15H11NO4I4 Mr = 776.6 B C15H7NO4I8 Mr = 1280.2 C C30H25NO6I4 Mr = 1002.6 D C30H21NO6I8 Mr = 1506.2

Question

How many moles of oxygen, O2, are needed to burn 1 mol of ethane if the products of the reaction are water and carbon only? A 1.5 B 3 C 3.5 D 5

Question

Which compound has the smallest difference in electronegativity between its two elements? A KF B KBr C LiF D LiBr

Question

VSEPR theory should be used to answer this question. Hydrazine has the following structure. hydrazine H H X N N H H What is the predicted bond angle X? A 90° B 107° C 109.5° D 120°

Question

This question is about buckminsterfullerene, graphite, iodine and diamond. How many of these substances have a simple molecular structure? A 0 B 1 C 2 D 3

Question

A student reacts 1 mol of magnesium powder in a sealed 0.030 m3 container of oxygen at a pressure of 2.0 × 105 Pa and a temperature of 600 K. The magnesium reacts completely to form MgO. Which percentage of the oxygen will be used up? A 5.0% B 10% C 42% D 83%

Question

Which equation represents an enthalpy change that is the average bond energy of the C–H bond in methane? A 1 4 C(g) + H(g) → 1 4 CH4(g) B 1 4 CH4(g) → 1 4 C(g) + H(g) C CH4(g) → C(g) + 4H(g) D CH4(g) → CH3(g) + H(g)

Question

Magnesium carbonate decomposes when heated in a Bunsen burner flame. Values for the standard enthalpies of formation, , of the species involved are shown. MgCO3 = –1095.8 kJ mol–1 MgO = –601.7 kJ mol–1 CO2 = –393.5 kJ mol–1 What is the standard enthalpy change for the decomposition of magnesium carbonate? A +100.6 kJ mol–1 B +887.6 kJ mol–1 C +1095.8 kJ mol–1 D +2091 kJ mol–1

Question

NH4NO3 decomposes into N2O and H2O on heating. Which statements are correct? 1 The ammonium ion is behaving as a reducing agent. 2 The nitrate(V) ion is behaving as an oxidising agent. 3 It is a redox reaction. 4 It is a disproportionation reaction. A 1, 2, 3 and 4 B 1, 2 and 3 only C 3 and 4 only D 3 only

Question

A student adds 3 mol of acidified K2Cr2O7 to an excess of I– ions. The chromium is all reduced to Cr3+ and I– ions are oxidised to I2. The I2 released is reduced back to I– ions by X mol of S2O32– ions. 1 mol of I2 is reduced by 2 mol of S2O32– ions. What is the value of X? A 3 B 6 C 9 D 18

Question

Which statement about acids and bases is always correct? A An acid with two H atoms per molecule will be stronger than an acid with one H atom per molecule. B A concentrated solution of a strong acid will have a lower pH than a dilute solution of a weak acid. C A concentrated solution of a strong base will have a lower pH than a dilute solution of a weak base. D A strong acid is more dissociated in solution than a strong base.

Question

The reaction between sulfur dioxide and oxygen is reversible. 2SO2(g) + O2(g) 2SO3(g) Kc = 280 mol–1 dm3 at 1000 K In an equilibrium mixture at 1000 K the sulfur trioxide concentration is 6.00 mol dm–3. The sulfur dioxide concentration is twice the oxygen concentration. What is the sulfur dioxide concentration? A 0.175 mol dm–3 B 0.252 mol dm–3 C 0.318 mol dm–3 D 0.636 mol dm–3

Question

The Boltzmann distribution of the particles in a mixture of gas X and gas Y is shown in diagram 1. diagram 1 percentage of particles 0 0 energy X and Y react and the reaction causes an increase in gas molecules present. The reaction goes to completion. In experiment 1, the increase in volume is measured every 10 seconds. During the reaction, the temperature and pressure remain constant. The increase in volume is shown in the volume–time graph in diagram 2. diagram 2 increase in volume / cm3 0 0 time / s In experiment 2, the experiment is repeated using identical amounts of X and Y. A different temperature is used compared to experiment 1. The same pressure is used. The Boltzmann distribution of the second mixture of X and Y is shown in diagram 3. During the reaction the temperature and pressure remain constant. diagram 3 percentage of particles 0 0 energy Which curve on the volume–time graph would show the increase in volume against time for experiment 2? (The original line for experiment 1 is redrawn as a solid line.) A B increase in volume / cm3 C D 0 0 time / s

Question

When the temperature of a particular reaction is increased by 10 °C (e.g. from 20 °C to 30 °C) the rate of the reaction approximately doubles. What is the most significant reason for this increase? A a different mechanism for the reaction B an increased collision frequency of the reactant molecules C more collisions have energy greater than the activation energy D a reduced activation energy for the reaction

Question

Which ion has the smallest radius? A Al 3+ B Ba2+ C Mg2+ D Na+

Question

Which row is correct? element with the greater element with an fifth ionisation energy amphoteric oxide A aluminium aluminium only B aluminium both aluminium and phosphorus C phosphorus aluminium only D phosphorus both aluminium and phosphorus

Question

Each of the chlorides listed is added to water. 1 aluminium chloride 2 magnesium chloride 3 silicon tetrachloride 4 phosphorus pentachloride Which chlorides form an aqueous solution that reacts with sodium carbonate to produce carbon dioxide? A 1 and 2 only B 3 and 4 only C 1, 3 and 4 only D 1, 2, 3 and 4

Question

NaOH(aq) is added to separate samples of magnesium chloride and barium chloride solutions. H2SO4(aq) is then added slowly to each reaction mixture until in excess. What is observed at the end of the reaction sequence? MgCl 2(aq) BaCl 2(aq) A colourless solution only colourless solution only B colourless solution only white precipitate C white precipitate colourless solution only D white precipitate white precipitate

Question

A 4.00 g sample of an anhydrous Group 2 metal nitrate, Z, is heated strongly until there is no further change of mass. A solid residue of mass 1.37 g is formed. Which metal is present in Z? A barium B calcium C magnesium D strontium

Question

Chlorine is bubbled through a cylinder containing aqueous sodium iodide and an immiscible layer of hexane. excess gas out chlorine gas hexane aqueous sodium iodide As the bubbles pass through the cylinder, what is observed in the lower and upper layers? lower aqueous layer upper hexane layer A colourless solution becomes brown colourless liquid becomes coloured B colourless solution becomes brown colourless liquid is unchanged C brown solution becomes colourless colourless liquid becomes coloured D brown solution becomes colourless colourless liquid is unchanged

Question

Chlorine and bromine have different volatilities. Which row identifies the more volatile of the two elements, and gives the correct explanation? identity of the explanation for the more volatile element difference in volatility A bromine intermolecular forces are greater in bromine than they are in chlorine B bromine intermolecular forces are greater in chlorine than they are in bromine C chlorine intermolecular forces are greater in bromine than they are in chlorine D chlorine intermolecular forces are greater in chlorine than they are in bromine

Question

Ammonium chloride dissolves readily in water. Which statement about the colourless solution formed is correct? A Ions in the solution can form hydrogen bonds with water molecules. B The solution is slightly basic. C The solution would smell of chlorine. D When sodium hydroxide is added, a gas is formed which turns damp blue litmus paper red.

Question

At 550 °C nitrogen dioxide reacts with unburnt hydrocarbon fragments, such as CH3, in the catalytic converter of a motor vehicle. 4CH3 + 7NO2 → 3 21 N2 + 4CO2 + 6H2O Which row gives the energy change for this reaction and a possible reason for it? energy change reason why the reaction is endothermic of reaction or exothermic A endothermic chemical energy is converted to heat energy B endothermic the N≡N bond energy is very high C exothermic CO2 and H2O have negative values D exothermic double bonds are broken in NO2

Question

Compound X contains an alcohol group and a carbonyl group. compound X OH O Which row is correct? type of type of alcohol group carbonyl group A primary aldehyde B primary ketone C tertiary aldehyde D tertiary ketone

Question

The diagram shows the skeletal formula of phenazine. phenazine N N What is the empirical formula of phenazine? A C6H4N B C6H6N C C12H8N2 D C12H12N2

Question

The diagram shows the structural formula of mevalonic acid. mevalonic acid H OH H H HO2C C C C C OH H CH3 H H Which reagent and conditions will react with mevalonic acid to produce an organic compound without a chiral carbon atom? A heat under reflux with CH3OH / H+ B heat under reflux with Cr2O72– / H+ C Na at room temperature D PCl 5 at room temperature

Question

Structural isomerism and stereoisomerism should be considered when answering this question. Y is a gaseous hydrocarbon which decolourises aqueous bromine. 10.0 g of Y occupies a volume of 3.43 dm3 under room conditions. How many isomeric structures are possible for Y? A 4 B 5 C 6 D 7

Question

Limonene is found in lemon and orange oils. limonene What is the major product when limonene reacts with an excess of dry hydrogen chloride? A B C D Cl Cl Cl Cl Cl Cl

Question

Which statement concerning the hydrolysis of 1-bromopropane with water is correct? A The hydrolysis reaction between water and 1-iodopropane is faster because the C–Br bond is less polar than the C–I bond. B The hydrolysis reaction with water is very slow because water is a weak electrophile. C The mechanism of the reaction involves the formation of a stable carbocation. D The reaction is slower with 1-chloropropane because the C–Cl bond is stronger than the C–Br bond.

Question

Compound J, C15H23Br2Cl , is reacted with an excess of a hot concentrated solution of sodium hydroxide in ethanol. One of the products is X. compound J excess NaOH Cl Br in ethanol X Br What could be the skeletal formula of X? A B C D

Question

Structural isomerism only should be considered when answering this question. Several compounds with molecular formula C4H8O2 have one carbonyl group and one OH group. How many of these compounds produce yellow crystals with alkaline I2(aq) at room temperature? A 2 B 3 C 4 D 5

Question

Pentaerythritol is used as an intermediate in the manufacture of paint. pentaerythritol HOCH2 CH2OH C HOCH2 CH2OH Which statement is correct? A Pentaerythritol can be dehydrated by concentrated sulfuric acid to form an alkene. B The empirical formula and molecular formula of pentaerythritol are different. C Pentaerythritol does not react with acidified potassium manganate(VII). D One mole of pentaerythritol gives two moles of hydrogen gas on reaction with an excess of sodium.

Question

Which reaction has a nucleophilic addition mechanism and gives a good yield of product under the stated conditions? A 1-bromopropane reacting with hot ethanolic sodium hydroxide B 2-iodopropane reacting with hot aqueous sodium hydroxide C propanal reacting with hydrogen cyanide under alkaline conditions D propanal reacting with hydrogen cyanide under acidic conditions

Question

A carbonyl compound has the structural formula CH3COCHO. Which row is correct for the observations made when this compound is treated with the given reagents? 2,4-DNPH reagent Fehling’s reagent A silver mirror red precipitate B silver mirror orange precipitate C orange precipitate silver mirror D orange precipitate red precipitate

Question

An ester is shown. H H H O H C H H C C C H H H O C C H H H C H H Which two compounds react to form this ester? A 2-methylpropan-1-ol and propanoic acid B 2-methylpropan-2-ol and propanoic acid C propan-1-ol and 2-methylpropanoic acid D 2-methylpropan-2-ol and ethanoic acid

Question

Which compound can be used to make propanoic acid by treatment with a single reagent? A CH2=CHCH2CH3 B CH3CH2CH2CN C CH3CH(OH)CN D CH3CH(OH)CH3

Question

A sample of sulfur consists mostly of 32S. It also contains 4.2% 34S and 2.8% 36S. No other isotopes of sulfur are present. What is the relative atomic mass, Ar, of this sample of sulfur? A 32.1 B 32.2 C 34.0 D 34.3

Question

One molecule of an addition polymer containing 2000 repeat units has an Mr of 112 000. The polymer molecule contains chiral centres. What is a possible monomer for this polymer? A CH2=CHCH3 B CH2=C(CH3)2 C CH2=CHCH2CH3 D CH2=CHCH2CH2CH3 Important values, constants and standards molar gas constant R = 8.31 J K–1 mol–1 Faraday constant F = 9.65 × 104 C mol–1 Avogadro constant L = 6.02 × 1023 mol–1 electronic charge e = –1.60 × 10–19 C molar volume of gas Vm = 22.4 dm3 mol–1 at s.t.p. (101 kPa and 273 K) Vm = 24.0 dm3 mol–1 at room conditions ionic product of water Kw = 1.00 × 10–14 mol2 dm–6 (at 298 K (25 °C)) specific heat capacity of water c = 4.18 kJ kg–1 K–1 (4.18 J g–1 K–1) The Periodic Table of Elements Group 1 2 13 14 15 16 17 18 1 2 H He hydrogen helium Key 1.0 4.0 3 4 atomic number 5 6 7 8 9 10 Li Be atomic symbol B C N O F Ne lithium beryllium name boron carbon nitrogen oxygen fluorine neon 6.9 9.0 relative atomic mass 10.8 12.0 14.0 16.0 19.0 20.2 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar sodium magnesium aluminium silicon phosphorus sulfur chlorine argon 23.0 24.3 3 4 5 6 7 8 9 10 11 12 27.0 28.1 31.0 32.1 35.5 39.9 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 39.1 40.1 45.0 47.9 50.9 52.0 54.9 55.8 58.9 58.7 63.5 65.4 69.7 72.6 74.9 79.0 79.9 83.8 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 20 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 85.5 87.6 88.9 91.2 92.9 95.9 – 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3 55 56 57–71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 lanthanoids Cs Ba Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn caesium barium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon 132.9 137.3 178.5 180.9 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 – – – 87 88 89–103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 actinoids Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og francium radium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson – – – – – – – – – – – – – – – – – 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 lanthanoids La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium 138.9 140.1 140.9 144.4 – 150.4 152.0 157.3 158.9 162.5 164.9 167.3 168.9 173.1 175.0 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 actinoids Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium – 232.0 231.0 238.0 – – – – – – – – – – –