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Question 21N.2.sl.TZ0.8a

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Date November 2021 Marks available [Maximum mark: 2] Reference code 21N.2.sl.TZ0.8a
Level sl Paper 2 Time zone TZ0
Command term Suggest Question number a Adapted from N/A
a.
[Maximum mark: 2]
21N.2.sl.TZ0.8a

Fast moving helium nuclei (4He2+) were fired at a thin piece of gold foil with most passing undeflected but a few deviating largely from their path. The diagram illustrates this historic experiment.

Figure from PPLATO / FLAP (Flexible Learning Approach To Physics), http://www.met.reading.ac.uk/pplato2/h-flap/
phys8_1.html#top 1996 The Open University and The University of Reading.

(a)

Suggest what can be concluded about the gold atom from this experiment.

[2]

Markscheme

Most 4He2+ passing straight through:

most of the atom is empty space
OR
the space between nuclei is much larger than 4He2+ particles
OR
nucleus/centre is «very» small «compared to the size of the atom» ✔

 

Very few 4He2+ deviating largely from their path:

nucleus/centre is positive «and repels 4He2+ particles»
OR
nucleus/centre is «more» dense/heavy «than 4He2+ particles and deflects them»
OR
nucleus/centre is «very» small «compared to the size of the atom» ✔

 

Do not accept the same reason for both M1 and M2.

Accept “most of the atom is an electron cloud” for M1.

Do not accept only “nucleus repels 4He2+ particles” for M2.

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