2021 P1 Q1 - Deflection of Subatomic Particle Through Electric Field
Let's take a look at 2021 A Levels H2 Chemistry Paper 1 Question 1.
We are required to deduce if the following statements about deflection of a beam of protons and electrons through an electric field are correct.
1. The electrons are deflected to a larger extent than the protons.
The angle of deflection of a particle through an electric field is directly proportionate to its charge-mass ratio.
Since the mass of an electron is much smaller than that of a proton, its charge-mass ratio is significantly higher.
So we will expect the electron beam to be deflected to a greater extent and statement 1 is correct.
2. The electron beam is deflected in the opposite direction to the proton beam.
Since electrons and protons are oppositely charged, they should be attracted to different poles.
Hence statement 2 is correct.
3. The proton beam travels in a straight path towards the negatively charged plate.
Travelling in a straight path means there is constant attraction and deflection as the proton beam gets closer to the negative pole.
Travelling in a curved trajectory means there is increasing attraction and deflection as the proton beam approaches the negative electrode.
There should be a stronger attraction between the proton beam and negative pole when they are closer together hence a curved path is more reasonable.
Hence statement 3 is incorrect.
We can now compare our options and determine the answer to be option B (1 and 2 only).
Topic: Atomic Structure, Physical Chemistry, A Level Chemistry, Singapore
Back to list of questions for 2021 A Level H2 Chemistry Paper 1.
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