AQA A-Level Chemistry Paper 3, 2021: Question 7
1 mark · Easy difficulty · Multiple Choice
Ultraviolet and Visible Light Absorption Contexts This multiple-choice question asks students to identify which of four processes does not involve absorption of UV or visible light.
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Question text
07 Which does not involve the absorption of ultraviolet radiation or visible light?
[1 mark]
A The blue appearance of copper(II) sulfate solution in daylight.
B The breakdown of ozone in the upper atmosphere.
C The ionisation of a molecule in a mass spectrometer.
D The reaction between chlorine and methane at room temperature.
Mark scheme
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Question Marking Guidance Mark Comments
07 C 1 the ionisation of a molecule in a mass spectrometer
How to answer it
Multiple Choice Explained: Which does not involve the absorption of UV or visible light?
Correct Answer: C – The ionisation of a molecule in a mass spectrometer
Why? In mass spectrometry, ionisation is caused by a high-energy electron beam, not by UV or visible light. The molecule is bombarded with electrons which knock out an electron to form a positive ion.
Why A is incorrect:
The blue appearance of copper(II) sulfate solution in daylight occurs because it absorbs some wavelengths of visible light and transmits others (mainly blue), so this does involve absorption of visible light.
Why B is incorrect:
The breakdown of ozone in the upper atmosphere involves absorption of UV radiation , which provides energy to break the O–O bonds in ozone. This is a key part of UV protection by the ozone layer.
Why D is incorrect:
The reaction between chlorine and methane at room temperature is initiated by UV light which causes homolytic fission of the Cl–Cl bond, forming chlorine radicals that drive the chain reaction. This definitely involves UV absorption.
Topics
Physical Chemistry · 3.1.1 Atomic Structure
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.