A nucleus ZAX emits one alpha particle.
(i) Explain how its atomic number and mass number change as a result of this emission.
(ii) Show that the neutron number of the nucleus decreases by 2 in this process.
(iii) If the original neutron–to–proton ratio was ZN, express the new neutron–to–proton ratio after the decay in terms of N and Z. State whether this ratio increases or decreases and justify your answer briefly.