10 minutes maximum! Can you do it in 5?

Q1-5. These questions are about the standard model of particles.

Here are 4 options:

  • A. dd
  • B. udd
  • C. Z
  • D. νe

Which of the above is...

1. .. a baryon?
2. .. a lepton?
3. .. a neutron?
4. .. an exchange particle?
5. .. a meson?


6-9. These questions are about beta decay.

A student write down an incorrect version of beta decay as shown here:

uud → udd + e- + νe

The equation must be incorrect because it breaks one or more conservation laws. Which of the 3 conservation laws, charge, baryon number and lepton number are not conserved in this equation?

Charge baryon number lepton number
conserved conserved not conserved
not conserved not conserved conserved
not conserved conserved not conserved
conserved not conserved not conserved

7. Which exchange particle is involved in nuclear beta decay?

  • A. intermediate vector boson
  • B. gluon
  • C. graviton
  • D. photon

8. What single change needs to be made to the equation shown above to correct the equation?

  • A. change νe to νe
  • B. change udd to dd
  • C. change e- to μ
  • D. change e- to e+
9. A different version of beta decay is shown here as a Feynman diagram, with a neutron decaying into a proton. Beta decay Feynman diagram

What feature of the diagram is incorrect?

  • A. The νe particle should be νe.
  • B. The e- arrow is pointing the wrong way.
  • C. The exchange particle line should be a straight line.
  • D. The νe arrow is pointing the wrong way.

10. The Rutherford-Geiger-Marsden experiment led to the discovery of the nucleus. It involved firing alpha particles at thin gold leaf foil.

Geiger Marsden Experiment diagram

What result led Rutherford to conclude that most of the atom was 'empty space'?

  • A. Most of alpha particles bounced back at the source, with few being deflected.
  • B. Most of alpha particles were deflected through small angles, with few continuing straight through the foil.
  • C. Most of alpha particles were absorbed, with few continuing straight through the foil.
  • D. Most of alpha particles went straight through the gold foil, with few being deflected.