Chemistry Paper 2 November 2019

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1. AIt is the limiting reagent that determines the maximum yield of salt formed.
2. BIt is an indicator that changes colour to show the end point of the reaction.
3. CIt is a catalyst that increases the rate of the neutralisation reaction.
4. DIt is a buffer that keeps the pH of the mixture constant throughout the titration.

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1. AAn atom or group of atoms that has lost or gained one or more electrons.
2. BAn atom with the same number of protons as another atom of the same element, but a different number of neutrons.
3. CA group of two or more atoms chemically bonded together.
4. DThe smallest part of an element that can take part in a chemical reaction.

1. AAn atom with the same number of protons as another atom of the same element, but a different number of neutrons.
2. BA group of two or more atoms of different elements chemically bonded together.
3. CAn atom that has gained or lost electrons to acquire an overall electric charge.
4. DAn atom with the same number of neutrons as another atom of the same element, but a different number of protons.

1. A8
2. B10
3. C12
4. D14

1. ADisplacement.
2. BPrecipitation.
3. CRedox, involving the transfer of electrons between reactants.
4. DNeutralisation.

1. A2
2. B3
3. C4
4. D5

1. ANo effect -- the amount of NaCl formed stays the same, since NaOH is the limiting reagent and its amount is unchanged.
2. BThe reaction reverses, converting the NaCl formed back into NaOH and HCl.
3. CThe amount of NaCl formed doubles, since more HCl reacts to form more salt.
4. DThe amount of NaCl formed halves, since the excess HCl dilutes the salt formed.

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1. AGlobal warming due to the enhanced greenhouse effect.
2. BDepletion of the ozone layer.
3. CAcid rain formation.
4. DEutrophication of water bodies, caused by excess nitrate and phosphate fertiliser runoff.

1. AExactly in the middle of the tube, because both gases diffuse at the same rate.
2. BAt the NH3 end only, because HCl gas does not diffuse.
3. CCloser to the HCl end, because ammonia gas diffuses faster than hydrogen chloride gas.
4. DCloser to the NH3 end, because hydrogen chloride gas diffuses faster than ammonia gas.

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1. AThe concentration of the ammonia and hydrochloric acid used.
2. BThe length of the glass tube used.
3. CThe temperature of the surroundings.
4. DThe material used to make the stopper, provided it seals the tube completely.

1. A-6
2. B+4
3. C+6
4. D+8

1. A-2
2. B-1
3. C+1
4. D+2

1. ACovalent, dative, and hydrogen bonding, as found in water and ammonia molecules.
2. BIonic, metallic, and dative bonding.
3. CIonic, covalent, and dative (coordinate) bonding.
4. DIonic, covalent, and metallic bonding.

1. ABaCO3 (barium carbonate, formed later from M and carbon dioxide)
2. BBaO (barium oxide, compound L, not yet reacted with water)
3. CBa(OH)2
4. DBaSO4 (barium sulfate, formed later from M and sulfuric acid)

1. A1.68 g
2. B0.03 g
3. C3 g
4. D6 g

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1. AC4H8
2. BC2H4
3. CC3H8
4. DC4H10

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1. AInsert a glowing splint into the gas -- the splint relights.
2. BAdd aqueous bromine (bromine water) -- the orange/brown colour is decolourised.
3. CAdd aqueous sodium hydroxide -- a coloured precipitate forms.
4. DBubble the gas through limewater -- the limewater turns milky.

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1. AAddition reaction.
2. BFree radical substitution.
3. CEsterification, the reaction between an acid and an alcohol.
4. DNeutralisation.

1. AA neutralising agent, such as dilute sodium hydroxide.
2. BA dehydrating agent, such as concentrated sulfuric acid.
3. CA reducing agent, such as hydrogen gas with a nickel catalyst.
4. DAn oxidising agent, such as acidified potassium dichromate(VI).

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1. ABacterial decomposition of organic matter in the absence of oxygen.
2. BIncomplete combustion of fuels.
3. CComplete combustion of fuels.
4. DCombustion in car engines at high temperature and pressure, forming gas from atmospheric nitrogen and oxygen.

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