Suggest which quarks or antiquarks make up a ${\pi }^{-}$ meson.

 Draw a diagram similar to Figure to show ${\mathrm{\beta }}^{+}$ - dacay.

A visual representation of the change within the neutron as it decays into a proton.

Write an equation to describe the changes in ${\mathrm{\beta }}^{+}$ - decay.

A visual representation of the change within the neutron as it decays into a proton.

The equation ${}_1{}^1\mathrm{p}\to {}_0{}^1\mathrm{n}+{}_{+1}{}^0\beta +\nu$ represents ${\beta }^{+}$ decay.

Use the equation to explain why the neutrino $\nu$ can have no charge and very little mass.

What are the differences between a proton, a positron and a photon? You can describe how their masses differ, how their charges differ or whether they are

particles or antiparticles.

Which of the interactions is not possible?

(a) ${}_2{}^4\mathrm{He}+{}_0{}^1\mathrm{n}\to {}_2{}^5\mathrm{He}$

(b)  ${}_{84}{}^{209}\mathrm{Po}\to {}_{82}{}^{205} \mathrm{Pb}+{}_2{}^4\alpha$

(c)  ${}_8{}^{14}\mathrm{O}\to {}_7{}^{14} \mathrm{N}+{}_1{}^0\beta +{}_0{}^0\nu$

(d) ${}_{14}{}^{31}\mathrm{Si}\to {}_{15}{}^{31} \mathrm{N}+{}_{-1}{}^0\beta +{}_0{}^{0}v$