16) (a) 11248Cd is more abundant because it has an even number of protons (48) and neutrons (64).
(b) 2713Al is more abundant because it has an odd number of protons (13) and an even number of neutrons (14). There are very few stable nuclei having an odd number of both protons and neutrons ruling out 3013Al.
(c) 10646Pd is more abundant because it has an even number of protons (46) and neutrons (60).
(d) 12854Xe is more abundant because it has an even number of protons (54) and neutrons (74).