18A.1 Bonding and stability of benzene Quiz: Pearson Edexcel Chemistry, Unit 18

The 20 questions

1. What type of hybridisation is shown by carbon atoms in benzene?

   • sp hybridisation
   • sp3 hybridisation
   • sp2 hybridisation
   • d2sp3 hybridisation

2. How do carbon-carbon bond lengths in benzene compare to C-C and C=C bonds?

   • Equal to C=C
   • Longer than C-C
   • Equal to C-C
   • Intermediate length

3. How many pi electrons are shared across the ring in a benzene molecule?

   • Twelve
   • Two
   • Six
   • Three

4. The measured enthalpy of hydrogenation of benzene is -208 kJ mol-1. Cyclohexene has an enthalpy of hydrogenation of -120 kJ mol-1. What is the delocalisation energy of benzene?

   • 152 kJ mol-1
   • 360 kJ mol-1
   • 208 kJ mol-1
   • 88 kJ mol-1

5. Which carbon-carbon bond is the longest among ethane, benzene, and ethene?

   • Ethyne C≡C
   • Ethene C=C
   • Ethane C-C
   • Benzene C-C

6. What is the approximate carbon-carbon bond order in a benzene molecule?

   • 1.0
   • 1.5
   • 2.0
   • 3.0

7. Which type of atomic orbitals overlap sideways to form the pi system in benzene?

   • p-orbitals
   • d-orbitals
   • s-orbitals
   • sp2 hybrid orbitals

8. How many pi electrons are delocalised in benzene?

   • 6
   • 2
   • 3
   • 12

9. How many sigma bonds are there in one molecule of benzene, C6H6?

   • 12
   • 6
   • 9
   • 15

10. What feature in the benzene skeletal formula represents the delocalised pi electrons?

    • Double bonds
    • Inner circle
    • Outer hexagon
    • Dotted lines

11. What is the approximate C-C bond length in benzene?

    • 0.134 nm
    • 0.154 nm
    • 0.120 nm
    • 0.139 nm

12. What is the C-C-C bond angle in a planar benzene ring?

    • 120 degrees
    • 109.5 degrees
    • 180 degrees
    • 90 degrees

13. How does the hydrogenation enthalpy of benzene compare to the predicted Kekule value?

    • Identical value
    • More exothermic
    • Less exothermic
    • Endothermic

14. What main type of reaction does benzene undergo to preserve its delocalised ring?

    • Nucleophilic substitution
    • Free radical addition
    • Electrophilic substitution
    • Electrophilic addition

15. What happens when benzene is shaken with bromine water at room temperature?

    • No colour change
    • Forms white precipitate
    • Decolourises rapidly
    • Turns dark purple

16. Why does benzene burn with a smoky flame in air?

    • High oxygen content
    • Low boiling point
    • Low C to H ratio
    • High C to H ratio

17. Delocalisation energy of benzene is calculated using the enthalpy change of which reaction?

    • Hydrogenation
    • Neutralisation
    • Combustion
    • Formation

18. What name is given to the 152 kJ mol-1 enthalpy difference between benzene and cyclohexa-1,3,5-triene?

    • Delocalisation energy
    • Lattice energy
    • Activation energy
    • Hydration energy

19. What feature of benzene attracts electrophiles?

    • High electronegativity
    • Positively charged ring
    • Weak sigma bonds
    • High electron density

20. Equal C-C bond lengths in benzene contradict which proposed structure?

    • Trigonal planar model
    • Kekulé structure
    • Delocalised model
    • Arenium intermediate

Related quizzes

• Electrophilic substitution of benzene Quiz · 18A.2 · 20 questions
• Phenol and its bromination Quiz · 18A.3 · 20 questions
• Amines: identification, basicity and reactions Quiz · 18B.1 · 20 questions
• Preparing amines and amides Quiz · 18B.2 · 20 questions
• Polyamides and amino acids Quiz · 18B.3 · 20 questions
• Proteins and the peptide bond Quiz · 18B.4 · 20 questions
• Deducing formulae from data Quiz · 18C.1 · 20 questions
• Planning multi-step reaction schemes Quiz · 18C.2 · 20 questions
• Practical preparation and purification Quiz · 18C.3 · 20 questions
• Sub-atomic particles, isotopes and relative masses Quiz · 1.1.1 · 20 questions