Organic Chemistry (OCR Gateway GCSE Chemistry: Combined Science)

Exam Questions

51 mins21 questions
11 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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21 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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31 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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11 mark

Heptane is an alkane with seven carbons.

What is the chemical formula of heptane?

  • C7H10

  • C7H12

  • C7H14

  • C7H16

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21 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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31 mark

Which of the following molecules is an alkene?

  • C6H10

  • C4H10

  • C5H10

  • C6H14

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41 mark

Which molecule can be cracked to produce hexane, C6H14?

  • C4H8

  • C4H10

  • C6H12

  • C10H22

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51 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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61 mark

Crude oil is separated into fractions by fractional distillation.

Look at the diagram of the fractions made in fractional distillation.

q7-paper-2-nov-2020-ocr-gcse-chem

Which of these fractions has the lowest boiling point?

  • Bitumen

  • Diesel oil

  • Gases

  • Petrol

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71 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.

q11-paper-2-specimen-2016-ocr-gcse-chem

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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81 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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11 mark

Crude oil is separated into fractions by fractional distillation.

Look at the diagram of the fractions made in fractional distillation

q3-paper-4-nov-2020-ocr-gcse-chem

Which of these fractions has the strongest intermolecular forces?

  • Bitumen

  • Diesel oil

  • Gases

  • Kerosene

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21 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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