CHEMISTRY OCR B - A-LEVEL
EXAM
1. When colour is absorbed by a surface, what colour is seen?
A. The absorbed colours
B. The complementary colour
✅ C. The colours not absorbed (reflected)
D. The transmitted colours
2. What are complementary colours?
A. Colours that absorb each other
✅ B. Colours which combine together to produce white light
C. Colours that cannot be seen by the human eye
D. Opposite shades on a colour wheel
3. What is the mechanism for EM radiation interacting with a surface to produce
a colour?
✅ A. When substances absorb EM radiation, electrons are excited from their ground state
and emit energy as EM radiation when they fall back
B. When substances reflect all visible light
C. When electrons are permanently removed
D. When energy is absorbed in the visible spectrum only
4. What is the equation that links frequency and wavelength?
A. E = mc²
✅ B. c = fλ
C. λ = hf
D. c = h/λ
1
,5. Why are some compounds colourless?
✅ A. Their electronic transitions require greater energy, absorbing UV radiation instead
of visible light
B. They reflect all visible light
C. They absorb visible light equally
D. They have no electrons
6. What is a conjugated system?
✅ A. Alternating double and single bonds
B. Only double bonds
C. Single bonds separated by lone pairs
D. A system of ionic bonds
7. What is the structure of benzene?
✅ A. Cyclic planar molecule
B. Linear molecule
C. Tetrahedral molecule
D. Non-planar cyclic molecule
8. What is an aromatic compound?
✅ A. A molecule with a cyclic conjugated system with chemistry typified by benzene
B. Any molecule with an odour
C. Any hydrocarbon with double bonds
D. A molecule containing oxygen
9. What happens to the valence electrons in benzene?
✅ A. Two form C–C sigma bonds, one bonds to hydrogen, and one is delocalised in p
orbitals above and below the ring
B. All form sigma bonds
2
, C. All form pi bonds
D. One electron is free
10. What is unique about the carbon–carbon bond length in benzene?
✅ A. It is between a single and a double bond length
B. It is the same as a single bond
C. It is longer than a double bond
D. It alternates between two lengths
11. What is the Kekulé structure?
✅ A. Alternating double and single bonds
B. Delocalised ring
C. Only single bonds
D. Only double bonds
12. Why is benzene more stable than Kekulé’s structure?
✅ A. Benzene has delocalised electrons, making it more stable than cyclohexa-1,3,5-triene
B. Benzene has more double bonds
C. Benzene is saturated
D. Benzene absorbs more UV
13. How do we prove benzene’s delocalised structure using enthalpy change?
✅ A. The enthalpy change of hydrogenation is less than expected for three double bonds,
showing extra stability
B. Benzene releases more energy
C. Benzene reacts faster
D. Benzene decolourises bromine water
14. How else do we know Kekulé’s model is incorrect?
3
EXAM
1. When colour is absorbed by a surface, what colour is seen?
A. The absorbed colours
B. The complementary colour
✅ C. The colours not absorbed (reflected)
D. The transmitted colours
2. What are complementary colours?
A. Colours that absorb each other
✅ B. Colours which combine together to produce white light
C. Colours that cannot be seen by the human eye
D. Opposite shades on a colour wheel
3. What is the mechanism for EM radiation interacting with a surface to produce
a colour?
✅ A. When substances absorb EM radiation, electrons are excited from their ground state
and emit energy as EM radiation when they fall back
B. When substances reflect all visible light
C. When electrons are permanently removed
D. When energy is absorbed in the visible spectrum only
4. What is the equation that links frequency and wavelength?
A. E = mc²
✅ B. c = fλ
C. λ = hf
D. c = h/λ
1
,5. Why are some compounds colourless?
✅ A. Their electronic transitions require greater energy, absorbing UV radiation instead
of visible light
B. They reflect all visible light
C. They absorb visible light equally
D. They have no electrons
6. What is a conjugated system?
✅ A. Alternating double and single bonds
B. Only double bonds
C. Single bonds separated by lone pairs
D. A system of ionic bonds
7. What is the structure of benzene?
✅ A. Cyclic planar molecule
B. Linear molecule
C. Tetrahedral molecule
D. Non-planar cyclic molecule
8. What is an aromatic compound?
✅ A. A molecule with a cyclic conjugated system with chemistry typified by benzene
B. Any molecule with an odour
C. Any hydrocarbon with double bonds
D. A molecule containing oxygen
9. What happens to the valence electrons in benzene?
✅ A. Two form C–C sigma bonds, one bonds to hydrogen, and one is delocalised in p
orbitals above and below the ring
B. All form sigma bonds
2
, C. All form pi bonds
D. One electron is free
10. What is unique about the carbon–carbon bond length in benzene?
✅ A. It is between a single and a double bond length
B. It is the same as a single bond
C. It is longer than a double bond
D. It alternates between two lengths
11. What is the Kekulé structure?
✅ A. Alternating double and single bonds
B. Delocalised ring
C. Only single bonds
D. Only double bonds
12. Why is benzene more stable than Kekulé’s structure?
✅ A. Benzene has delocalised electrons, making it more stable than cyclohexa-1,3,5-triene
B. Benzene has more double bonds
C. Benzene is saturated
D. Benzene absorbs more UV
13. How do we prove benzene’s delocalised structure using enthalpy change?
✅ A. The enthalpy change of hydrogenation is less than expected for three double bonds,
showing extra stability
B. Benzene releases more energy
C. Benzene reacts faster
D. Benzene decolourises bromine water
14. How else do we know Kekulé’s model is incorrect?
3
