Which of the following ions has the greatest number of unpaired electrons?
[tex]\mathrm{Sn}^{4+}[/tex]
[tex]\mathrm{Mn}^{4+}[/tex]
[tex]\mathrm{Y}^{3+}[/tex]
[tex]\mathrm{Ag}^{+}[/tex]
[tex]\mathrm{Cl}[/tex]