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Question 19M.2.SL.TZ1.2a.ii

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Date May 2019 Marks available [Maximum mark: 3] Reference code 19M.2.SL.TZ1.2a.ii
Level SL Paper 2 Time zone TZ1
Command term Sketch Question number a.ii Adapted from N/A
a.ii.
[Maximum mark: 3]
19M.2.SL.TZ1.2a.ii

Silicon-30  ( 14 30 Si) can be formed from phosphorus-30 ( 15 30 P) by a process of beta-plus decay.

(a.ii)

Sketch the Feynman diagram that represents this reaction. The diagram has been started for you.

[3]

Markscheme

correct change of either u to d ✔

W+ shown ✔

correct arrow directions for positron and electron neutrino ✔

Allow ECF from MP2 in ai for MP3.

Examiners report

Few candidates were awarded full marks for a variety of reasons for the Feynman diagram they drew, and many left this question blank. It should be noted that on the exam the time axis can either be vertical or horizontal, so candidates should be familiar with both methods of drawing Feynman diagrams. Candidates should be able to draw Feynman diagrams from scratch either way. The examiners were looking for the basics of drawing a diagram (proper change in quark structure, proper exchange particle, and proper arrow directions for the positron and neutrino).

Syllabus sections