(a(i))[1]
Most of the alpha particles pass straight through the thin foil. State what this observation tells you about atoms.
(a(ii))[4]
Some of the alpha particles are deflected through angles less than $90^{\circ}$ and a few are deflected through $180^{\circ}$. State and explain two conclusions about the nuclei of atoms from this observation.
(b(i))[1]
State the change in the nucleus that happens when a $\beta$-particle is emitted.
(b(ii))[3]
Calculate the mass of the strontium isotope that decays in $87\,\text{years}$.