Three nuclides are listed below.
Nuclide P : 714N
Nuclide Q : 614C
Nuclide R : 715N
Answer the following questions about them.
(i) State clearly what is meant by (a) isotope, (b) isobar and (c) isotone.
(ii) Identify the pair(s) among P, Q and R that are (a) isotopes, (b) isobars and (c) isotones. Give a brief reason for each identification.
(iii) For each nuclide, calculate its neutron–proton ratio (N/Z) and arrange the three nuclides in increasing order of this ratio.
(iv) Using the ratios obtained in part (iii), explain which of the three nuclides is expected to be the least stable against radioactive decay. Justify your answer qualitatively with reference to the belt of stability.