Q279 · Practice questionSimple familiar1 mark
QUESTION 279
Which statement correctly compares a proton with an electron in the Standard Model?
(A)
Both are elementary particles because both are electrically charged.
(B)
A proton is elementary; an electron is made of quarks.
(C)
A proton is a three-quark baryon; an electron is an elementary lepton.
(D)
A proton is a meson; an electron is an elementary gauge boson.
WORKED SOLUTION
1 markAnswer C
ANSWER
C. A proton is a three-quark baryon; an electron is an elementary lepton.
Worked solution
A proton has quark content uud and is composite. The electron is an elementary lepton in the Standard Model. Electric charge alone does not determine whether a particle is elementary.
Equivalent physically justified methods, alternative valid sketches and consistent units accepted.
Accept sensible significant figures and consistent rounding from stated constants.
Select C.
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