WAEC Chemistry 2014 Paper

Concept:$$\text{A diamagnetic substance has no unpaired electrons and is not attracted to a magnetic field.}$$Explanation:Magnetic attraction in transition metals depends on the presence of unpaired electrons.Iron, $\mathrm{Fe}$, has unpaired $3d$ electrons, so it is attracted to a magnetic field.Titanium, $\mathrm{Ti}$, also has unpaired electrons in the $3d$ subshell, so it is attracted.Copper, $\mathrm{Cu}$, has the configuration $[\mathrm{Ar}]\,3d^{10}4s^{1}$, which contains one unpaired electron.Zinc, $\mathrm{Zn}$, has the configuration $[\mathrm{Ar}]\,3d^{10}4s^{2}$; all its electrons are paired.Therefore, zinc is diamagnetic and is not attracted to an external magnetic field.Answer:D. $\mathrm{Zn}$