Classification of Particles

The classification of hadrons into baryons and mesons and their interactions Baryon number as a conserved quantum number in all interactions Lepton number conservation separately for electron and muon leptons Strangeness as a quantum number and its conservation rules in strong and weak interactions The properties and decay modes of pions, kaons and muons

A-Level Physics AQA 14 questions 15 mins

Preview Questions

Q1. Which of the following correctly describes what makes a particle a hadron?

Multiple Choice · 1 point

· It is a fundamental particle that does not experience any force
· It is subject to the strong interaction
· It has a non-zero lepton number
· It must be electrically charged

Q2. Which of the following correctly classifies the proton and the pion?

Multiple Choice · 1 point

· Both are baryons
· Both are mesons
· Proton is a baryon, pion is a meson
· Proton is a meson, pion is a baryon

Q3. What is the baryon number of an antiproton?

Multiple Choice · 1 point

· +1
· 0
· -1
· +2

Q4. Which of the following interactions would violate conservation of baryon number?

Multiple Choice · 1 point

· p → n + e⁺ + vₑ
· p + p → p + p + π⁰
· n → p + e⁻ + v̄ₑ
· p → e⁺ + π⁰

Q5. Which of the following is the only stable baryon into which all other baryons eventually decay?

Multiple Choice · 1 point

· Neutron
· Pion
· Proton
· Kaon

Q6. Which particle acts as the exchange particle of the strong nuclear force between nucleons?

Multiple Choice · 1 point

· Kaon
· Photon
· W boson
· Pion

Q7. Which of the following correctly describes a kaon?

Multiple Choice · 1 point

· A baryon that decays via the strong interaction
· A meson that is produced via the strong interaction and decays via the weak interaction
· A lepton that decays into a pion
· A meson that is both produced and decays via the strong interaction

Q8. Which of the following particles are classified as leptons?

Multiple Choice · 1 point

· Proton, neutron, electron
· Pion, kaon, muon
· Electron, muon, electron neutrino, muon neutrino
· Electron, proton, muon neutrino

Q9. A muon decays as follows: μ⁻ → e⁻ + v̄ₑ + vμ. Which conservation laws are satisfied in this decay?

Multiple Choice · 1 point

· Conservation of baryon number only
· Conservation of muon lepton number and electron lepton number
· Conservation of strangeness only
· Conservation of charge only

Q10. Which of the following correctly gives the lepton numbers for an electron antineutrino?

Multiple Choice · 1 point

· Electron lepton number = +1, muon lepton number = 0
· Electron lepton number = -1, muon lepton number = 0
· Electron lepton number = 0, muon lepton number = -1
· Electron lepton number = 0, muon lepton number = +1

Q11. Strange particles are always produced in pairs in the strong interaction. Which quantum number reflects this?

Multiple Choice · 1 point

· Baryon number
· Lepton number
· Strangeness
· Charge

Q12. A kaon with strangeness S = +1 is produced alongside another strange particle in a strong interaction. What must the strangeness of the other particle be?

Multiple Choice · 1 point

· +1
· 0
· -1
· +2

Q13. By how much can strangeness change in a weak interaction?

Multiple Choice · 1 point

· It cannot change at all
· It can change by 0, +1 or -1
· It can change by any integer value
· It can only change by +1

Q14. Put the following particles in order, from largest to smallest baryon number.

Ordering · 1 point

1. Proton (B = +1)
2. Pion (B = 0)
3. Antiproton (B = -1)
4. Antineutron (B = -1) - same as antiproton, both antimatter baryons

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