Final answer:
Ti4+ is expected to be diamagnetic because, after losing four electrons, it has no unpaired electrons left in its electronic configuration, unlike the other options provided which have unpaired d-electrons and are thus paramagnetic.
Step-by-step explanation:
The question asks which of the following actions would be expected to be diamagnetic: Cu2+, Zn+, Al2+, Ti4+, Fe2+. A diamagnetic species has no unpaired electrons and is not attracted to a magnetic field. To determine the magnetic character of these cations, we should consider their electron configurations, specifically the d-electrons since these are transition metal cations. Diamagnetic cations will have all their electrons paired.
Among the options given, Ti4+ is the cation that would be expected to be diamagnetic. Titanium, when neutral, has the electron configuration [Ar]4s2 3d2. Removing four electrons to get the Ti4+ cation leaves it with an electron configuration of [Ar], which means all electrons are paired. Unlike Ti4+, the other cations (Cu2+, Zn+, Al2+, Fe2+) have unpaired d-electrons, making them paramagnetic rather than diamagnetic.