The quarks inside protons and neutrons

Science · Matter & Materials · ages 17-18

Name ______________________ Date ____________

A neutron is up, down, down. What charge does that add to?
- Plus 1
- Minus 1
- 0
What is the quark content of a proton?
- Up, down, down
- Up, up, down
- Down, down, down
In beta-minus decay, a down quark turns into an up quark.
Circle one: True False
A neutron decays by beta-minus. What are the products?
- Proton plus electron plus antineutrino
- Two protons plus a photon
- Neutron plus positron only
Which three tallies must match on both sides of a reaction?
- Mass, speed, and colour
- Protons, neutrons, and electrons
- Charge, baryon number, and lepton number
How do quarks and leptons differ?
- Leptons feel the strong force
- Quarks group into hadrons; leptons do not
- Both group into hadrons
A particle is built from up, up, strange, where strange carries minus one third like down. What is its charge?
- 0
- Plus 2
- Plus 1
A student writes neutron to proton plus electron and stops. What is missing?
- An antineutrino is missing
- Nothing is missing
- A photon is missing

Answer key

For grown-ups. Fold this page away before handing over the rest.

0 · Two thirds minus one third minus one third is exactly zero.
Up, up, down · Two ups and one down add to plus one, the proton's charge.
True · That single flip converts the neutron into a proton.
Proton plus electron plus antineutrino · The quark flip yields a proton, and the electron plus antineutrino balance the books.
Charge, baryon number, and lepton number · Those three conserved counts judge every proposed reaction.
Quarks group into hadrons; leptons do not · Quarks bind through the strong force into hadrons, while leptons stay solitary.
Plus 1 · Two thirds plus two thirds minus one third is plus one, by the same arithmetic.
An antineutrino is missing · Without the antineutrino the lepton tally reads zero against one.