(a)[1]
From the list below, underline every particle that is not fundamental: antineutrino, baryon, nucleon, positron.
(b)[2]
A thorium-230 nucleus $\left(^{230}_{90}\text{Th}\right)$ undergoes a sequence of decays, emitting $\alpha$-particles and $\beta^{-}$-particles, until it becomes a lead-206 nucleus $\left(^{206}_{82}\text{Pb}\right)$. Determine how many $\alpha$-particles in total and how many $\beta^{-}$-particles in total are emitted in the decay sequence that produces lead-206 from thorium-230.
(c)[2]
A meson carries a charge of $-1e$, where $e$ is the elementary charge. Its quark composition includes a charm antiquark. State and explain one possible flavour (type) of the other quark in the meson.