A graph of nucleon number A against proton number Z is shown in Fig. 7.1. [Figure 7.1] The graph shows a cross (labelled P) that represents a nucleus P. Nucleus P decays by emitting an α particle to form a nucleus Q. Nucleus Q then decays by emitting a β⁻ particle to form a nucleus R.

1. (a)On Fig. 7.1, use a cross to represent
2. (a)(i)nucleus Q (label this cross Q),[1]
3. (a)(ii)nucleus R (label this cross R).[1]
4. (b)State the name of the class (group) of particles that includes the β⁻ particle.[1]
5. (c)The quark composition of one nucleon in Q is changed during the emission of the β⁻ particle. Describe this change to the quark composition.[1]

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