(a)[2]
State one similarity and one difference between a down quark and a down antiquark.
(b)
For the aluminium-25 nucleus $^{25}_{13}\text{Al}$:
(b(i))[1]
State how many protons and how many neutrons there are.
(b(ii))[1]
Show that the charge equals $2.1\times10^{-18}\,\text{C}$.
(c)[3]
In (b), the nucleus is shifted in a straight line from point A to point B through a uniform horizontal electric field in a vacuum, as shown in Fig. 8.1. The electric field strength is $11\,\text{kV m}^{-1}$. Calculate the work done to move the charge from A to B.