1
1 mark
Look at the displayed formula of an organic compound.
What is the name of this compound?
Butanoic acid
Butanol
Propanoic acid
Propanol
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Organic Chemistry (OCR GCSE Chemistry A (Gateway)): Exam Questions
Exam code: J248
3 hours62 questions
2
1 mark
DNA is a condensation polymer made from monomers called nucleotides.
How many different nucleotides are used to make DNA molecules?
2
3
4
5
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3
1 mark
What is the name of the process that converts large alkane molecules into smaller alkane molecules?
Cracking
Fractional distillation
Hydrogenation
Polymerisation
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4
1 mark
Which displayed formula shows an alkene?
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5
1 mark
A student bubbles ethene gas into bromine water.
What is observed?
Colour change from blue to colourless
Colour change from colourless to orange
Colour change from orange to colourless
Orange precipitate is made
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6
1 mark
What is the formula of the functional group in alcohols?
−CH3
−COOH
−CO2
−OH
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7
1 mark
What is the displayed formula of ethanol?
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8
1 mark
Methane is a hydrocarbon.
Which substance cannot be produced when methane burns in air?
Carbon
Carbon dioxide
Hydrogen
Water
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9
1 mark
Crude oil is a resource that is being made extremely slowly.
Which word describes a resource that is being made extremely slowly?
Finite
Hydrocarbon
Non‐renewable
Petrochemical
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10
1 mark
Which of these homologous series can form addition polymers?
Alcohols and carboxylic acids
Alkenes and alkanes
Alkenes only
Carboxylic acids only
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1
1 mark
Heptane is an alkane with seven carbons.
What is the chemical formula of heptane?
C7H10
C7H12
C7H14
C7H16
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2
1 mark
The complete combustion of pentane, C5H12, takes place in the following unbalanced equation:
_C5H12 + _O2 → _CO2 + _H2O
What numbers will balance the reaction?
1,4,5,3
1,8,5,6
2,8,5,6
2,4,5,6
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3
1 mark
Which of the following molecules is an alkene?
C6H10
C4H10
C5H10
C6H14
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4
1 mark
The following molecule can undergo addition polymerisation.
What it the correct repeat unit?.
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5
1 mark
Which of the following is not true about DNA?
The structure is a double helix
DNA is made from nucleotides
DNA is made from two polymer chains
The monomers that form DNA are amino acids
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6
1 mark
The structure of a polymer is shown below.
What is the correct monomer?
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7
1 mark
Hydrogen fuel cells can be used to power trains.
Why could people refer to the hydrogen fuel cell trains as the 'new' steam trains?
The hydrogen used is extracted from fossil fuels
The hydrogen fuel cell trains are slower than diesel trains
The reaction produces water that can be released as steam
The reaction in the fuel cell is a combustion reaction
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8
1 mark
Hydrogen fuel cells are often used instead of rechargeable batteries in spacecraft.
Which of the following is not an advantage of using hydrogen fuel cells in spacecraft?
Water is the only product made in the reaction
The fuel cells have no moving parts so are easy to maintain
Hydrogen and oxygen are easily made by electrolysis of water
Hydrogen fuel cells are cheap
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9
1 mark
Which molecule can be cracked to produce hexane, C6H14?
C4H8
C4H10
C6H12
C10H22
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10
1 mark
Crude oil is a mixture of hydrocarbons.
Crude oil is separated into useful fractions.
Which of these mixtures of substances could be in a fraction from crude oil?
C2H4, C4H10, C4H10O
C2H4, C2H3Br, C4H10
C2H6, C3H8, C4H10
C2H6, C2H3Br, C4H10O
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11
1 mark
What happens to the potential difference of a chemical cell once the reactants are used up?
It decreases
It increases
It starts and finishes at 0 V
It stays the same
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12
1 mark
Crude oil is separated into fractions by fractional distillation.
Look at the diagram of the fractions made in fractional distillation.
Which of these fractions has the lowest boiling point?
Bitumen
Diesel oil
Gases
Petrol
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13
1 mark
What type of reaction takes place between an alkene and hydrogen?
Addition
Dehydration
Neutralisation
Thermal decomposition
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14
1 mark
DNA molecules are polymers.
What is the name of the monomers that make up DNA molecules?
Amino acids
Carbohydrates
Nucleotides
Proteins
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15
1 mark
Which of the following are the first four members of the homologous series of alcohols?
CH4, C2H6, C3H8, C4H10
CH3OH, C2H5OH, C3H7OH, C4H9OH
HCOOH, CH3COOH, C2H5COOH, C3H7COOH
C2H4, C3H6, C4H8, C5H10
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16
1 mark
Look at the displayed formula of the monomer butene.
What is the formula of the polymer formed from butene?
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17
1 mark
The bar chart shows the amount of some fractions made from 100 tonnes of crude oil by fractional distillation.
It also shows the amount of each fraction needed for everyday uses.
Cracking converts large molecules into smaller more useful molecules to make the supply match the demand.
Which fractions are most likely to be cracked to make the supply match the demand?
Gas oil and fuel oil
Gas oil and petrol
Naphtha, paraffin and fuel oil
Petrol and gases
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18
1 mark
What is the formula of the product in this equation?
C2H2Br
C3Br4
C2H3Br
C2H4Br2
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19
1 mark
Which displayed formula includes the functional group of an alcohol?
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20
1 mark
What is the general formula of the fractions produced by the fractional distillation of crude oil?
CnH2n
CnH2n+2
C2H2n+1OH
C2n+2H2
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21
1 mark
Which displayed formula shows butanol?
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22
1 mark
Higher Only
Look at the equations for the reactions that happen at each side of a hydrogen‑oxygen fuel cell. Reaction 1: 2H2 (g) → 4H+ (aq) + 4e– Reaction 2: 4H+ (aq) + O2 (g) + 4e– → 2H2O (g)
| Reaction 1 | Reaction 2 |
A | Oxidation because electrons are gained | Reduction because electrons are lost |
B | Reduction because electrons are gained | Reduction because electrons are gained |
C | Oxidation because electrons are lost | Reduction because electrons are gained |
D | Oxidation because electrons are lost | Oxidation because electrons are lost |
Which row of the table, A, B, C or D, is correct about reactions 1 and 2?
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23
1 mark
A student reacts a hydrocarbon with bromine water.
The formula of the product is C3H6Br2.
Which is the displayed formula of the hydrocarbon?
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24
1 mark
A student bubbles ethene gas into bromine water.
Which displayed formula shows the product of this reaction?
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25
1 mark
Which of these homologous series can react together to form addition polymers?
Alcohols and carboxylic acids
Alkenes only
Alkenes and alkanes
Carboxylic acids only
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26
1 mark
A student heats compound X with acidified potassium manganate(VII) solution.
The product of the reaction is compound Y.
What is the colour change seen during this reaction?
Colourless to orange
Colourless to purple
Orange to colourless
Purple to colourless
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27
1 mark
What is the formula of the functional group in alcohols?
−CH3
−COOH
−CO2
−OH
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1
1 mark
Crude oil is separated into fractions by fractional distillation.
Look at the diagram of the fractions made in fractional distillation
Which of these fractions has the strongest intermolecular forces?
Bitumen
Diesel oil
Gases
Kerosene
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2
1 mark
Look at the structure of glycine.
Glycine is a monomer that reacts to form proteins.
Glycine contains two different functional groups that allow it to undergo polymerisation. What are the two functional groups?
−NH2 and −C=O
−NH2 and −CH2−
−NH2 and −OH
−NH2 and −COOH
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3
1 mark
Higher Only
Which statement explains why polyamides are condensation polymers?
A molecule of water forms each time a hydroxyl link forms.
A molecule of water forms each time an ester link forms.
A molecule of water forms each time an amine group reacts with a carboxylic acid group.
A molecule of water forms each time an alcohol group reacts with a carboxylic acid group.
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4
1 mark
Which fraction is collected at the top of the fractional distillation column?
| Melting point range (°C) | Boiling point range (°C) |
A | –70 – –60 | 20 – 25 |
B | –50 – –40 | 30 – 50 |
C | 0 – 20 | 100 – 120 |
D | 20 – 40 | 130 – 160 |
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5
1 mark
What is the correct balanced equation for the combustion of hexane, C6H14?
C6H14 + 13O2 → 6CO2 + 7H2O
C6H14 + 6O2 → 6CO2 + 7H2O
2C6H14 + 19O2 → 12CO2 + 14H2O
2C6H14 + 26O2 → 12CO2 + 14H2O
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6
1 mark
Polyesters can be made by condensation polymerisation. Ethanediol can react with butanedioic acid (a carboxylic acid containing two -COOH groups) to make a polymer.
Which of the following is a correct repeat unit for this polymer?
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7
1 mark
Which of the following shows the product of the reaction between propene and bromine?
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8
1 mark
Ethene, C2H4, reacts with bromine, Br2, in an addition reaction.
Which is the balanced symbol equation for this reaction?
C2H4 + Br2 → C2H3Br + HBr
C2H4 + Br2 → C2H4Br2
C2H4 + 2Br2 → C2Br4 + 2H2
C2H4 + 2Br2 → C2H4Br4
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9
1 mark
A hydrogen-oxygen fuel cell produces electricity.
Hydrogen reacts with oxygen to produce water.
What is the equation for the reaction that happens at the anode?
2H2 (g) + O2 (g) → 2H2O (g)
4H+ (aq) + 4e- → 2H2 (g)
2H2 (g) → 4H+ (aq) + 4e-
4H+ (aq) + O2 (g) + 4e- → 2H2O (g)
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10
1 mark
Higher Only
Which pairs of molecules would react to form a polyester?
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11
1 mark
Which statement about chemical cells is correct?
They produce a voltage indefinitely.
They produce a voltage once all of the reactants are used up.
They produce a voltage until one of the reactants is completely used up.
They produce a voltage until the reactants are partly used up.
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12
1 mark
Ethane is a very small hydrocarbon molecule.
Which row about ethane is correct?
| Easy to ignite? | Boiling point |
A | ✔ | high |
B | x | high |
C | ✔ | low |
D | x | low |
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13
1 mark
Ethene, C2H4, reacts with bromine in an addition reaction.
What is the structural formula of the product?
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14
1 mark
What is the half equation for the reaction at the anode in a hydrogen/oxygen fuel cell?
2H2 + O2 → 2H2O
2H2 → 4H+ + 4e–
4H+ + 4e– → 2H2
4H+ + O2 + 4e– → 2H2O
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