AQA A-Level Chemistry Paper 3, 2021: Question 15
1 mark · Medium difficulty · Multiple Choice
This question assesses your ability to deduce the correct compound from a given molecular formula by recognising the structure of aromatic compounds and applying knowledge of bonding and functional groups.
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Question text
15 In which molecule are all the atoms in the same plane?
[1 mark]
A CH3CHO
B CH3NH2
C C6H5Cl
D C6H5CH3
Mark scheme
Show the mark scheme
15 C 1 C6H5Cl
How to answer it
Q: In which molecule are all the atoms in the same plane?
A. CH3CHO
Ethanal has a trigonal planar carbon in the carbonyl group, but the CH3 group is tetrahedral, so not all atoms lie in the same plane.
Ethanal has a trigonal planar carbon in the carbonyl group, but the CH3 group is tetrahedral, so not all atoms lie in the same plane.
B. CH3NH2
Methylamine contains tetrahedral geometries around both the carbon and nitrogen atoms. The molecule is not planar.
Methylamine contains tetrahedral geometries around both the carbon and nitrogen atoms. The molecule is not planar.
C. C6H5Cl
Chlorobenzene is planar — all atoms in the benzene ring and the chlorine substituent are in the same plane due to the sp2 hybridisation of the ring and delocalised π bonding.
Chlorobenzene is planar — all atoms in the benzene ring and the chlorine substituent are in the same plane due to the sp2 hybridisation of the ring and delocalised π bonding.
D. C6H5CH3
In methylbenzene (toluene), the benzene ring is planar, but the CH3 group is tetrahedral around the methyl carbon and lies out of the plane.
In methylbenzene (toluene), the benzene ring is planar, but the CH3 group is tetrahedral around the methyl carbon and lies out of the plane.
Topics
Physical Chemistry · 3.1.3 Bonding
Question and mark scheme from the AQA A-Level Chemistry examination, Paper 3, 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.