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.

2021 p1 q1 question

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.

2021 p1 q1 angle of deflection

Since the mass of an electron is much smaller than that of a proton, its charge-mass ratio is significantly higher.

2021 p1 q1 compare charge mass ratio

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.

2021 p1 q1 compare charge

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.

2021 p1 q1 straight path

Travelling in a curved trajectory means there is increasing attraction and deflection as the proton beam approaches the negative electrode.

2021 p1 q1 curve path

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).

2021 p1 q1 answer

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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