Chemistry Paper 3 November 2019

1. Abent
2. Btetrahedral
3. Ctrigonal pyramidal
4. Dsquare planar

1. A$C_2H_6O$
2. B$C_3H_6O_3$
3. C$CH_2O$
4. D$C_2H_4O_2$

1. A10.2 %
2. B12.3 %
3. C24.6 %
4. D49.2 %

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1. AMgOH + HCl -> MgCl + H2O
2. BMg(OH)2 + HCl -> MgCl2 + H2O
3. CMg(OH)2 + 4HCl -> MgCl4 + 2H2O
4. DMg(OH)2 + 2HCl -> MgCl2 + 2H2O

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1. A$H_2CO_3 + OH^- \rightarrow HCO_3^- + H_2O$
2. B$HCO_3^- + H^+ \rightarrow H_2CO_3$
3. C$H_2CO_3 \rightarrow CO_2 + H_2O$
4. D$HCO_3^- + OH^- \rightarrow CO_3^{2-} + H_2O$

1. A1.05 g
2. B2.10 g
3. C4.21 g
4. D16.84 g

1. Aadding a catalyst
2. Badding water to the mixture
3. Cincreasing the total pressure
4. Dremoving water with a drying agent

1. Araises the blood pH well above neutral, which would kill many blood-borne bacteria
2. Bincreases the oxygen-carrying capacity of red blood cells during heavy exercise
3. Ckeeps blood pH almost constant, preventing enzyme denaturation
4. Dprevents blood from clotting inside blood vessels during circulation

1. AHCO3- + OH- -> CO3^2- + H2O
2. BHCO3- + H+ -> H2CO3
3. CH2CO3 + OH- -> HCO3- + H2O
4. DH2CO3 -> CO2 + H2O

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1. A$Mg(g) \rightarrow Mg^{2+}(g) + 2e^-$
2. B$Mg^+(g) \rightarrow Mg^{2+}(g) + e^-$
3. C$Mg^{2+}(g) \rightarrow Mg^{3+}(g) + e^-$
4. D$Mg(g) \rightarrow Mg^+(g) + e^-$

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1. A22.1
2. B24.3
3. C26.0
4. D27.6

1. Ain a further shell and is more shielded
2. Bpaired in the same orbital
3. Cin a d orbital of lower energy
4. Dheld by a greater nuclear charge

1. Athe energy released when one mole of gaseous atoms gains one mole of electrons
2. Bthe energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions
3. Cthe energy required to remove one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions
4. Dthe energy required to remove one electron from a single gaseous atom

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1. A2, 8, 8 electrons
2. B2, 8, 2 electrons
3. C8, 2, 2 electrons
4. D2, 10 electrons

1. Ais a simple covalent molecule with a low melting point that vaporises easily under engine heat
2. Bdissolves readily in the fuel-air mixture, preventing any conduction pathway from ever forming
3. Cis a giant ionic lattice with no mobile ions or electrons to carry charge, and has a very high melting point
4. Dcontains free-moving delocalised electrons throughout its structure that would readily conduct heat and electric current

1. ASiCl4 is simple covalent with weak van der Waals forces, while solid PCl5 exists as ionic [PCl4]+[PCl6]-
2. BSiCl4 forms extensive hydrogen bonds between its molecules but PCl5 is completely unable to do so
3. CPCl5 is simple covalent while SiCl4 is instead a giant ionic lattice held by strong electrostatic forces
4. DPCl5 has a considerably higher relative molecular mass than SiCl4, giving it far stronger intermolecular forces

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1. AMg(g) -> Mg^+(g) + e-
2. BMg^2+(g) + e- -> Mg^+(g)
3. CMg^+(g) -> Mg^2+(g) + e-
4. DMg(g) -> Mg^2+(g) + 2e-

1. A+3 and +1
2. B+5 and +1
3. C+5 and +3
4. D+1 and +5

1. A$2KClO_3 \rightarrow KClO_4 + KCl + O_2$
2. B$4KClO_3 \rightarrow 3KClO_4 + KCl$
3. C$2KClO_3 \rightarrow 2KCl + 3O_2$
4. D$2KClO_3 \rightarrow KClO_4 + KClO_2$

1. A58.5
2. B118.5
3. C133.0
4. D237.0

1. Aforms a blue precipitate
2. Bforms a white precipitate
3. Cstays colourless, with no precipitate forming
4. Dproduces a yellow-green gas above the solution

1. A3Cl2 + 6OH- -> 5Cl- + ClO3- + 3H2O
2. B3Cl2 + 6OH- -> 6Cl- + ClO3- + 3H2O
3. CCl2 + 6OH- -> 5Cl- + ClO3- + 3H2O
4. DCl2 + 2OH- -> Cl- + OCl- + H2O

1. Aa single compound decomposes into exactly two different elements
2. Bthe same species is simultaneously oxidised and reduced
3. Ca species transfers one electron to a completely different element
4. Dtwo different elements are both oxidised at the same time

1. Anickel(II) carbonate, NiCO3
2. Bmagnesium carbonate, MgCO3
3. Ccalcium carbonate, CaCO3
4. Dcopper(II) carbonate, CuCO3

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1. A$XCl_4 + 4H_2O \rightarrow X(OH)_4 + 4HCl$
2. B$XCl_4 + H_2O \rightarrow XO_2 + 2HCl + Cl_2$
3. C$XCl_4 + 2H_2O \rightarrow XO_2 + 2HCl + Cl_2$
4. D$XCl_4 + 2H_2O \rightarrow XO_2 + 4HCl$

1. Ahas a complete outer shell of eight electrons in $CCl_4$
2. Bforms ionic bonds with chlorine
3. Chas no accessible d orbitals for water to bond to
4. Dis less electronegative than chlorine

1. Aiodide ions are oxidised to iodate(V) ions
2. Bpotassium chloride is brown in solution
3. Ciodine is displaced from the iodide
4. Dchlorine forms a brown solution in water

1. Atrigonal pyramidal, 107°
2. Btetrahedral, 109.5°
3. Coctahedral, 90°
4. Dsquare planar, 90°

1. Athe +4 oxidation state of Pb is destabilised by the inert pair effect, while the C-Cl bonds in CCl4 are strong and carbon's +4 state is stable
2. BPbCl4 exists only as a simple covalent liquid at room temperature, while CCl4 behaves instead as a typical ionic solid
3. CCCl4 has a much higher relative molecular mass than PbCl4, giving it far stronger van der Waals forces overall
4. Dcarbon consistently forms much weaker covalent C-Cl bonds than lead forms in its Pb-Cl bonds

1. Anitrogen reacts only with reactive metals and never combines directly with oxygen gas at all
2. Bthe N triple bond is very strong, needing a high activation energy, unlike the weaker P-P single bonds in phosphorus
3. Cnitrogen gas molecules are far denser than phosphorus vapour molecules under identical laboratory conditions
4. Dphosphorus has a much lower melting and boiling point than elemental nitrogen gas at standard pressure

1. Aphosphorus is fundamentally unable to form multiple covalent bonds with any oxygen atoms whatsoever
2. Bnitrogen only reacts with atmospheric oxygen when the surrounding pressure is unusually high
3. Cnitrogen (period 2) has no accessible d orbitals to expand its octet, but phosphorus (period 3) can use d orbitals to form five bonds
4. Dnitrogen is considerably more electronegative than phosphorus, so it is only able to form a smaller number of bonds

1. Ahexane molecules are considerably more polar than water molecules under normal laboratory conditions
2. Bhalogens are much denser than both water and hexane, so they always sink below either solvent
3. Chalogen molecules are non-polar, so they dissolve poorly in polar water but readily in non-polar hexane
4. Dhalogens actually react chemically with water molecules but do not react at all with non-polar hexane

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1. Aa larger electron cloud and so stronger van der Waals forces
2. Bmore hydrogen bonds per molecule
3. Ca stronger O–H bond
4. Da branched chain which packs more closely

1. A2
2. B6
3. C8
4. D14

1. Aa primary $-CH_2OH$ group
2. Bthe $CH_3CH(OH)-$ group
3. Ca carboxylic acid group
4. Da carbon to carbon double bond

1. Athe alkyl groups in pentan-3-ol are more electron-donating, destabilising its conjugate base (alkoxide ion)
2. Bpropan-1-ol simply has a lower boiling point than pentan-3-ol under the same conditions
3. Cpentan-3-ol has a larger molecule with more inductive electron donation towards water
4. Dpropan-1-ol forms noticeably stronger hydrogen bonds to surrounding water molecules than pentan-3-ol

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1. A3CH3CH2CH(OH)CH2CH3 + 2Cr2O7^2- + 8H+ -> 3CH3CH2COCH2CH3 + 4Cr3+ + 7H2O
2. B3CH3CH2CH(OH)CH2CH3 + Cr2O7^2- + 14H+ -> 3CH3CH2COCH2CH3 + 2Cr3+ + 7H2O
3. CCH3CH2CH(OH)CH2CH3 + Cr2O7^2- + 8H+ -> CH3CH2COCH2CH3 + 2Cr3+ + 7H2O
4. D3CH3CH2CH(OH)CH2CH3 + Cr2O7^2- + 8H+ -> 3CH3CH2COCH2CH3 + 2Cr3+ + 7H2O

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1. A2,3-dimethylbut-2-ene
2. B3-methylpent-1-ene
3. Chex-1-ene
4. D2-methylpent-2-ene

1. A$S_N1$ nucleophilic substitution
2. B$S_N2$ nucleophilic substitution
3. Celectrophilic addition
4. Dfree radical substitution

1. Aa base
2. Ba nucleophile
3. Can oxidising agent
4. Da catalyst

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1. Aconcentrated $HNO_3$ alone at 100 °C
2. Bdilute $HNO_3$ and $AlCl_3$ at room temperature
3. C$NaNO_2$ and dilute HCl below 10 °C
4. Dconcentrated $HNO_3$ and concentrated $H_2SO_4$ at 55 °C

1. Adonate electron density to the carboxylate ion
2. Bincrease the relative molecular mass
3. Cform hydrogen bonds with water
4. Dwithdraw electron density and stabilise the carboxylate ion

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1. AY > Z > X
2. BZ > Y > X
3. CX > Y > Z
4. DX > Z > Y

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1. Aphenylamine > nitrobenzene > benzene
2. Bphenylamine > benzene > nitrobenzene
3. Cnitrobenzene > benzene > phenylamine
4. Dbenzene > phenylamine > nitrobenzene

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1. AX and Y actually hydrolyse at essentially the same rate, since both are simple aryl chloride compounds
2. BX's carbon attached to chlorine is unusually strongly electrophilic in this case, making it hydrolyse the very fastest
3. CY has a distinctly weaker C-Cl bond than X does, purely because of steric hindrance introduced by the ring
4. DY's carbonyl carbon is strongly electrophilic, while in X delocalisation of the chlorine lone pair into the ring strengthens the C-Cl bond

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1. Aa larger ionic radius
2. Ba higher nuclear charge
3. Ca completely filled 3d subshell
4. Da half filled 3d subshell

1. A1.6 g
2. B4.0 g
3. C6.4 g
4. D7.1 g

1. A8.00 g
2. B5.33 g
3. C6.40 g
4. D7.11 g

1. AFe3+ reacts directly with water molecules to form HCl gas
2. Biron(III) chloride is itself a strong Bronsted base
3. Cchloride ions hydrolyse in water to form hypochlorous acid
4. Dthe small, highly charged Fe3+ ion polarises coordinated water molecules, releasing H+ ions

1. Amanganese and chromium ions in these states are always far too large to fit six water molecules
2. Bthese particular transition metal ions are fundamentally unable to form any octahedral complexes at all
3. Cwater cannot act as a ligand for manganese or chromium in any oxidation state whatsoever
4. Dsuch high ionic charges would completely polarise and decompose the coordinated water ligands

1. Athe ratio of the concentrations of a solute in two immiscible solvents at equilibrium, at constant temperature
2. Bthe number of times an extraction must be repeated to remove all the solute
3. Cthe ratio of the volumes of the two immiscible solvents used in an extraction
4. Dthe amount of solute, in grams, that will dissolve in exactly 100 g of a chosen solvent at one fixed temperature

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1. Aremoves exactly the same amount of solute
2. Bremoves less solute overall
3. Chas no effect on the amount of solute removed
4. Dremoves more solute overall

1. AFe2+ has a completely filled 3d subshell that repels its outer electron
2. Blosing an electron gives Fe3+ the extra stability of a half-filled 3d5 subshell
3. CFe2+ is generally regarded as a considerably stronger reducing agent than Mn2+ in solution
4. DFe3+ consistently has a noticeably larger ionic radius than Fe2+ in aqueous solution

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1. Aheated activated charcoal
2. Bwater under high pressure
3. Ca slurry of calcium carbonate
4. Dconcentrated sulphuric acid

1. A1 to 100 nm
2. B100 to 1 000 nm
3. C1 000 to 10 000 nm
4. D0.1 to 1 nm

1. Astronger metallic bonding
2. Ba greater surface area to volume ratio
3. Ca higher melting point
4. Da lower density

1. Areduces the overall greenhouse effect by reflecting incoming sunlight back to space
2. Braises the pH of rainwater over time, making it noticeably more alkaline than normal rain
3. Cdissolves in atmospheric water to form acid rain, lowering the pH of soil and water
4. Dincreases the overall thickness of the stratospheric ozone layer significantly

1. ACa(OH)2 + SO2 -> CaSO4 + H2
2. BCaCO3 + 2SO2 -> Ca(SO3)2 + CO2
3. CCaO + SO2 -> CaSO3
4. DCaCO3 + SO2 -> CaSO3 + CO2

1. Adestroys all disease-causing pathogens present within the buried waste completely
2. Brequires no future management or monitoring of the land used at all
3. Cproduces methane, a flammable greenhouse gas, as waste decomposes
4. Dautomatically recovers all valuable materials from the waste stream for recycling

1. Ait produces no unpleasant odours or pests
2. Bit converts all buried waste into reusable compost
3. Cleachate produced can contaminate groundwater
4. Dit eliminates the need for any future waste collection

1. Aseparates recyclable, biodegradable and hazardous waste for appropriate treatment
2. Bactively prevents any of the collected waste from ever being recycled at all
3. Cis only ever legally required for genuinely hazardous waste streams specifically
4. Dsignificantly increases the total volume of waste that ultimately needs final disposal

1. Avehicles historically burned leaded petrol, depositing lead compounds from exhaust near roads
2. Blead compounds are deliberately added to vehicle tyres to improve their road grip
3. Clarge deposits of lead-rich ore are commonly found naturally beneath most road surfaces
4. Droad surface paint historically contained unusually high concentrations of lead compounds

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