1.3 The antiparticle of the electron $e^{-}$ is the positron $e^{+}$.
5.1 The quark content of the proton is $uud$.
6.2 The quark model explains the hadronic spectrum.
6.1 The quark model predicts the existence of baryons and mesons.
2.2 The concept of the neutrino was first proposed by Pauli in 1930.